1. Characteristics and Application of
Emulsifiers    
Introduction, Classification of Emulsifiers,                      
Solubility & Surface Activity of Emulsifi-
ers, Wetting and Detergent Strucures in
Emulsifier, Effect of Surfacant on the Pro- perties of Solutions, Wetting Charcteristics of Emulsifiers, Micellar Sol- uilization of Emulsifiers, Formulated Emulsifiers, Non- Surfactant Functional Additives, Inert Fill- ers, Functional Surfactant Additives, Uses of Emulsifiers, Household and Personal Products, Industrial Uses.

2. Industrial Uses of Emulsifier
Agriculture, Building and Construction, Elastomers and Plastics, Food and Beve- ra ges, Industrial Cleaning, Leather, Metals, Paper, Paints and Protective Coatings, Pe- troleum Production and Products, Textiles, Biodegradable Emulsifiers and Water Poll- ution, Biodegradation, Water Pollution, Re- cent Trends.

3. Anionic Surfactants      
Introduction,Carboxylates, Soap, N-Acyls- arcosinates, Acylated Protein Hydrolysates, Sulfonates, Alkyl benzene Sulfonates, Pet- roleum Sulfonates, Dialkyl Sulfosuccinates, Naphthalene Sulfonates, N-acyl-N-alkyl- taurates, 2-Sulfoethyl Es-ters of Fatty Acids, Olefin Sulphonates, Sulfates & Sulfated fates (Sulfated Alcohols), Sulfated Natural Fats and Oils,Sulfated Alkanolamides, Sulfated     Esters, Ethoxylated and Sulfated Alkyl
phenols, Ethoxylated and Sulfated Alco- hols, Phosphate Esters.

4. Non-Ionic Surfactants                
Introduction, Polyoxyethylene Surfactants,
Ethoxylated Alkyl Phenols, Eth -oxylated
Aliphatic Alcohols, Carboxylic Esters, Gl-
ycerol Esters, Polyethylene Glycol Esters,
Anhydrosorbitol Esters, Ethoxylated Anh-
ydrosorbitol Esters, Glycol Esters of Fatty
Acids, Ethoxylated Natural Fats, Oils and
Waxes, Carboxylic Amides, Diethanolami- ne Condensates, Monoalkanolamine Co- ndensates, Poly- oxyethylene Fatty Acids Amides, Poly- alkylene Oxide Block Cop- olymers, Poly- oxypropylene-Polyoxyeth- ylene Derivatives, Organo Silicones Deri- vatives.
5. Cationic, Amphoteric and Enzyme
Detergents  
Cationic Detergents, Amines not containing Oxygen, Oxygen— Containing Amines,
Except Amides, Amine Oxides, Polyoxy e-
thylene Alkyl and Alicyclic Amines, 2-Alkyl- 1-(hydroxy- ethyl)-2-imidazolines, N, N, N’ N’
-Tetrakis-substituted Ethylen ediamines, Other
Miscellaneous Cationic Surfactants, Amines Having Amide Linkages, Quaternary Ammon- ium Salts, Amphoteric Surfactants, Enzyme Detergents.

6. Sulfonated Oils                
Historical Background, Chemistry of Sulfation
    and Sulfonation, Applications of Sulfonated Oils,
Manufacture of Sulfonated Oils, Sulfation, Sulfonation, Sulfation of individual Oils, Characteristics and Analysis of Sulfonated Sulfated Oils.

7. Alkylolamides              
Introduction, Alkylolamides in Shampoo Formulations, Chemistery of the Alkylola- mides, Mono-Alkylolamides, Di-Alkylola- mides, Pure Di-Alkyl olamides, Phosphox- ylated Alkylolamides, Sulphated Alkylola- mides, Foam Stabilization, Manufacture of Alkylol- amides, Coconut Fatty Acid Die thanolamide, Lauric Acid Dieth anolamide, Oleic Acid Monoethan olamide, Stearic Acid Mono ethanolamide.

8. Vinylarene Polymers                              
Monomers, Anionic Polymerization, Polymer
Reactions, Stereoregular Polymerization, Ca- tionic Polymerization, Free-Radical Polymeri- zation, Polymer Properties, Electrical Proper- ties, Utility and Application.

9. N-Acyl-N-Alkyltaurates            
Introduction, Applications of Igepon T Produ- cts, Future of Igepons, Manufacture of Igepon T, Raw Materials, Oleic Acid Chloride, Igepon T Gel, Igepon T Powder, Chemical Control,Ut- ilities, Materials of Construction.

10. Vinylamine Polymers            
Preparation, Polymerization Followed by Hy- drolysis, Polymerization Followed by Reduc- tion, Hofmann Degradation of Poly(acrylamide), Polymerization Kinetics, Copolymers of Vinyl-,
Amine Properties, Chemical Reactions of Poly
(vinyl-mine), Uses.

11.   Alkyl Sulfates
Introduction, Manufacture of Alcohols, Pro- perties and Performance Characteristics of Alkyl Sulfates, Krafft Point, Critical Micelle Concentration, Surface and Interfacial Tens- ions, Wetting Time, Foam Height, Detergen- cy, Dishwashing Test, Emulsion Stability, M- anufacture of Alkyl Sulfates, Sulfation with Chlorosulfonic Acid, Sulfation with Sulfuric Acid, Sulfation with Sulfur Trioxide, Manuf- acture of Alkyl Sulfated on Large Scale, For- mulated Products from Alkyl Sulfates.

12. N-Vinyl Amide Polymers
Monomers, Manufacture, Polymerization, Pr- operties of Poly( vinyl Amides), Other Poly(vi- nyl Amides), Uses, Cosmetics and Toiletries, Textiles and Dyes, Pharmaceuticals, Adhesi- ves, Beverage Clarification, Miscellaneous Uses,
Specifications and Standards, Analytical and Test Methods, Health and Safety Factors.

13. Olefin Sulfate and Sulfonates
Introduction, Olefin Sulfates, Raw Materials and Product Composition, Olefin Sulfates from Shale Oil, Olefin Sulfate from Wax Cracked Distillates, Sulfation, Neutralization and Hydrolysis, Evaporation, Finishing, Solvent Recovery, Olefin Sulfates, Introduction, Products of Sulfonation, Manufacture of Olefin Sulfonates Introduction, Batch Sulfonation, Continuous
Sulfonation, Sulfonation with Dioxane- SO3 , Characteristics & Surface Active Properties of Olefin Sulfonates, Formulat- ed of Heavy-Duty Detergents with Ole- fin Sulfonates.

14. Ethoxylation Processes  
Introduction, Ethoxylated Alkyl Phenols, Laboratory Method of Preparation, Batch Ethoxylation Unit, Properties of Ethoxyl- ated Alkyl Phenols.

15. Ethoxylated Fatty Alcohols
Introduction, Laboratory Method of Prep- aration, Continuous Ethoxylation Unit, Pro- perties of Ethoxylated Fatty Alcohols, Sol- ubility, Cloud Point, Surface and Interfacial Tension, Detergency, Wetting Properties, Foaming Properties, Emulsifying Properties, Ethoxylated Fatty Acids, Introduction, Manu- facture, Properties of Fatty Acid Ethoxylates, Ethoxylated Fatty Amines, Formulations.

16. Alkyl Phenol Ether Sulfates    
Introduction, Sulfation and Sulfonation, Man- ufacture of Alkyl Phenol Ether Sulfates, Sul- famation, Nonylphenol 4-ethoxy Sulfate, Di- (isohexyl / isoheptyl)phenol Ether Sulfate, Do- decylphenol Ether Sulfate, Sulfation with Sulfur Trioxide, Comparison of Sulfation with Sulfur Trioxide and Sulfamic Acid, Properties and Performance Characteristics of Alkyl Phenol Ether Sulfates.

17.   Alkyl Ether Sulfates      
Introduction, Properties & Performance Char- acteristics of Alkyl Ether Sulfates, Individual
Alkyl Ether Sulfates, Tallow Alcohol Ether Su- lfates, Manufacture of Alkyl Ether Sulfates, Process Development, Manufacture of Alcohol Ether Sulfates, Formulated Products From Alkyl Ether Sulfates.

18. Fatty Amine Oxides
Introduction, Manufacture of Fatty Amine Oxi- des, Routes to Fatty Amines, Amine Oxidation, Commercial Synthesis, Properties and Analysis of Fatty Amine Oxides, Amine Oxide Propert- ies, Analytical Methods, Formulations and Use of Fatty Amine Oxides, Light- Duty Liquids, He- avy Duty Formulations.

19. Bisquaternery and Other Cationic
Softeners      
Introduction, Preparation of Bisqu- aterneries, 2- Butene-Bridged-Bisquat erneries,Dip-henyloxide- Bridged-Bis- quaterneries, Die- thyleneoxide-Bri- dged- Bisquaterneries, p-Xylylene-Bridged-Bisq- uaterneries,2-Butyne-Bridged-Bis- quaterneries, Performance Evaluation of Softeners, Multiwash Softeners Evaluati- on, Softness Evaluation, Rew- ettability Measurements, Performance Characteri- stics of Bisquaterneries and Other Cationics Soft- eners, Softener Concentration, Fabric Rew- ettab- ility Measurements.

20. Other Miscellaneous Emulsifiers                  

(i)   Alkyl Naphthalene Sulfonates
Introduction, General Method of Manufacture, Nekal ‘BXG’, Nekal ‘BX’ Extra Strong, Dibutyl Naphthalene Sulfonate, Diamyl Naphthalene Sulfonate.

(ii) Sulfated Alkylolamides
Introduction, Igepon ‘B’ Paste, Igepon ‘C’ Paste, Sodium-N-2-hydroxyethyl-hexa decanamide H Sulfate.

(iii) Sodium B-Sulfoethyl Esters of Fatty Acids
Introduction¬, Manufacture of Igepon A.

(iv) Polyethylene Glycol Fatty Acid Esters
Introduction, Manufacturing Process, Fatty Acid Esters of Sucrose.

(v) N-Acylsarcosinates
Introduction, Manufacture of Sodium N- Oleoylsarcosinate.

(vi) Sulfated Monoglyceride
Introduction, Manufacture.

21. Application of Emulsifiers                      

(i)   Pharmaceutical Emulsions
Introduction, Cod Liver Oil Emulsions, Oint- ments, Beeler’s Base, Washable Ointment Base, Greaseless Base, Ointment Washable Type, Steroidal Emulsion, Aeriflavine Oint- ment, Aluminium Acetate Lotion, Typical Antibiotic, Anesthetic and Anti-Inflammatory Ointment, O/W Type Benzyl Ointment, O/W Boric Acid Ointment, W/O Calamine Cream, W/O Emollient Ointment, Solubilized Hexach- lorophene, O/W Oxyquinoline Sulphate Oint- ment, Penicillin Ointment.

(ii) Rosin and Rubber Emulsion
Rosin Emulsion, PVA Resin Emulsion, Pent- aerythritol Abietate Emulsion, Methyl Meth- acrylate Emulsion, Polystyrene Resin Emulsion,
Polyvinyl Ether Emulsion, Synthetic Rubber Emulsion Polymerization, Chlorinated Rubber Emulsion, Wall Tile Adhesive, Black Industrial Cement, Reclaim Asphalt Dispersion Cement, General Purpose Cement, Rubber Dressing.

(iii)Textile Emulsions
Antistatic Textile Dressing, Lustre Emulsion for Starching, Rootproofing Emulsion, Textile Soft- eners, Textile Gloss Oil, Yarn Finish, Soluble Textile Oil, Rope Preservative, Synthetic Thread Lubricant, Acetate Rayon Oil, Screen Printing Emulsion, Mineral Oil Emulsion, Rayon Delustering.

(iv) Pesticides Emulsions
Malathion Wettable Powder, Dieldrin Formulation, Lindane Formulation, Ronnel Formulation, Butyl Ester of 2, 4-D Formulation, Fruit Coating Wax Emulsion, Cattle Dips, DDT Formulation, Chlor- dane Formulation, Heptachlor Formulation, Aldrin Formulation, Endrin Emulsion Concentrate.

(v) Food Emulsion
Chocolate Milk, Stabilized, Artificial Cream, Le- mon Oil Emulsion, Transparent Lemon Oil Emul- sion, Orange Emulsion, Bitter Almond Emulsion, Butter Substitute, Mayonnaise, Salad Dressings, Coffee Whitner Liquid, Coffee Whitner (Spray Dried), Ice Cream Mix, Pickle Flavour Emulsion, Starch Paste.

(vi) Emulsions in Paint Industry
Flat Interior Paint, Semigloss White Latex Paint, Gloss Emulsion Paint, Exterior Latex Paint, Exterior White Paint, Interior White Paint, Resin Oil Emulsion.

(vii)Emulsions in Polish Industry
Automobile Polish, ‘Dry Bright’ Floor Polish, Paste Polishes, Mineral Oil Emulsion Polishes, Silicone Polishing Cloth, Paste Type, Automobile Cleaner Polish.

(viii)Leather and Paper Treatment Emulsions
Leather Finishes, Fat Liquors, Leather Dressing,
Shoemaker’s Wax Burnishing Polish, Softner for Leather Goods, Leather Pasting, Coating for Paper, Water Resistant Coating for Paper, Grease Resistant Paper Coating.

(ix) Cutting Oils, Soluble Oils, Miscible Oils
Napthenic Miscible Oils, Cutting Oils, Mold Release Compound.

(x) Cleaners
All Purpose Cleaners, Pine Base Cleaner,
Hand Dishwashing Detergent, Machine Dish- washing Liquid, Household Heavy Duty Dete- rgent, Household Light Duty Detergent, Fine Fabric Detergent, Hydrogen Peroxide Emulsions, Floor Wax Remover, Rug Cleaner, Shoe Cleaner, Waterless Hand Cleaners, Acid Aluminium Clea- ner, Copper Cleaner, Degreaser Formulation, Light Duty Steam Cleaner, Alkaline Cleaner, Merceriza- tion Formulation, Powdered Caustic Bottle Wash- ing Compound, White Wall Tire Cleaner.

22. Determination of Physical Surface
    Active Characteristics of Emulsifiers            
Introduction, Physical Characteristics, Density of Powdered Detergents, Apparent Bulk Density, Cup Density, Particle Size of Powdered Deterge- nts, Hand Sieving, Machine Sieving, pH and Alk-
alinity, Free Alkalinity, Cloud Point of Non-ionic Detergents, Viscosity, Surface-Active Properties, Ring Method, Experimental Procedure, Determina- tion of Surface Tension, Determination of Interfac- ial Tension, Calculation of Surface Tension, Calcul- ation of Interfacial Tension, Performance Characte- ristics, Dishwashing Tests, Laundry Evaluation, Split Item Tests, Bundle Test, Foam Tests, Dynamic Foam Test, Pour Foam Test, Wetting Test, Canvas Disc Test, Skein Test.

23. Analysis of Emulsifiers  
Introduction, Separation of Surfactants, Identi-
fication of Components, Anionics, Cationics, Non-ionics, Determination of Surfactants, Total Organic Active Ingredient, Procedure, Correction for Sodium Chloride Content, Anionic Surfactants, Preliminary Estimate of Mol. Wt., Titration with Cationic Surfactants, Prepa raition and Standardiz- ation of Titrant, Titration of Sample, Amine Comp- lexation Method¬, Determination of Alkylaryl Sulf- onates, Determination of Alkylaryl Sulfonates in the Presence of Short Alkyl Chain Sulfonates, et- erniination of Fatty Alcohol Sulfates, Cationic Sur- factants, Determination of Amine Oxides, Non-Ionic Surfactants, Column Techniques, Batch Technique, Tooth Powders, Bath Powders, Light-Duty Liquid Detergent.

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Characteristics and Application of Emulsifiers

Introduction

Emulsifier is an organic compound that encompasses in the same molecule two dissimilar structural groups, e.g., a water soluble and a water insoluble moiety. The composition, solubility properties, localtion and relative sizes of these dissimilar groups in relation to the overall molecular configuration determine the surface activity of a compound. The water soluble moiety is generally referred to as hydrophilic, lipophobic and oleophobic and the water insoluble moiety is called hydrophobic, lipophilic and oleophilic. A surfactant in general possesses the following characteristic properties.

It must be soluble in at least one phase of a liquid system. Its molecules are composed of groups with opposing solubility tendencies. At the interphase of a liquid system it must form oriented monolayers and its equilibrium concentration at a phase interface is greater than its concentration in the bulk of the solution. It forms micelles if the concentration of the solute exceeds a limiting value in the bulk of the solution. Solutions of surfactants exhibit detergency, foaming, wetting, emulsifying, solubilizing and dispersing properties either individually or collectively.

Classification of Emulsifiers

Emulsifiers are classified on the basis of their hydrophilic or solubilizing groups into four categories — anionics, non-ionics, cationics and amphoterics. The anionic solubilizing groups are carboxylates, sulfonates, sulfates and phosphates. Non-ionics are solubilized by hydroxyl groups and polyoxyethylene chains. Primary, Secondary and tertiary amines and quaternary ammonium groups are the cationic solubilizers. Amphoteric surfactants are solubilized by some combination of anionic and cationic moieties; non-ionic solubilizing groups may also be part of amphoteric molecules. In addition to the primary solubilizing groups, other structural units c- ntribute to the hydrophilic tendencies of molecules, e.g., ester linkages and amide linkages. The hydrophobic, i.e. lipophilic, moieties are almost invariably hydrocarbon or halogen substituted hydrocarbon groups. Olefin linkages are less hydrophobic than carbon-to-carbon single bonds. Products based on silicon-containing hydrophobes are just beginning to be offered in commercial quantities.

Solubility & Surface Activity of Emulsifiers

Emulsifier solute usually displays maximum surface activity and functional effectiveness when it is near the threshold of insolubility. Moreover, the solubility of surfactants is markedly affected by temperature and electrolyte concentrations. Thus for each set of conditions there is usually an optimum solubility balance for each type of surfactant. Relatively small changes in the composition of a surfactant are often sufficient to change its solubility and hence its surface activity. There are many ways to effect such changes; for example the average molecular weight of the raw material mixture i.e. hydrophobe can be increased slightly or the degree of sulfation, sulfonation or ethoxylation can be increased or decreased. Empirical solubility tests rank with charge weights and chemical analysis as control techniques for surfactant manufacturing processes. They make it possible to produce to tight specifications by compensating for variations in successive lots of raw materials or to adjust a process to obtain a range of optimum performance conditions for essentially the same product but are pointed to different uses.

Wetting and Detergent Structures in Emulsifier

Correlations of functional properties with molecular structures have been sought by numerous investigators. One result has been the identification of strong wetting and strong detergent structures. The hydrophilic group of strong wetting agents is located at the middle of the hydrophobic chain or at the central branching point if the molecule contains two or more chains. Conversely, the hydrophilic group in strong detergents is located at the end of the hydro Characteristics and Application of Emulsifiers phobic chain.

Although the wetting and detersive properties of unformulated anionic and non-ionic compounds follow this structural pattern, usefulness of the generalization is limited to the selection of surfactants for a few specialized applications, e.g. textile wetting agents. This limitation is due to the pronounced superiority of formulated or ‘built’ products over pure compounds for detergency, emulsification etc. In formulations, detergency and wetting strength of individual components lose much of their significance. Textile wetting efficiency is not simply related to surface tension lowering, but dilute aqueous solutions of strong wetting agents characteristically have low surface tensions.

Effect of Surfactant on the Properties of Solutions

A surfactant changes the properties of a solvent in which it is dissolved to a much greater extent than would be expected from its concentration. This marked effect is due to: (1) adsorption at the solution interfaces, (2) orientation of the adsorbed surfactant ions of molecules, (3) miscelle formation in the bulk of the solution, and (4) orientation of the surfactant ions or molecules in the micelles. These effects are caused by the amphipathic structure of a surfactant molecule and the magnitude of the effects depends to a large extent on the solubility balance of the molecule. An efficient surfactant is usually relatively insoluble as individual ions in the bulk of a solution.

Wetting Characteristics of Emulsifiers

Wetting of a solid by a surfactant solution may represent either the displacement of air or some other gas from the solid surface by the solution of a liquid, e.g. an oil, from the solid surface. Wettability represents the tendency of a solid to be wetted and wetting power the tendency of a liquid to wet a solid. The wetting of one liquid by another immiscible liquid is visually apparent by the spreading of a film to create a large liquid-liquid interface, and lack of wetting is evidenced by the tendency of one liquid to form droplets in the form of a lens on the surface of the other.

The attraction between a solid or liquid to be wetted and the wetting solution determines the degree or completeness of wetting that can be attained. In practical applications, the speed of wetting may be as important as the completeness of wetting at equillibrium.

Many investigators have pointed out that rate of migration of surfactant molecules from the bulk of the solution to maintain the concentration of the interface is one limiting factor on the speed of wetting. Dynamic methods for measurement of the lowering of surface, free energy have been used to estimate the significance of this factor. The effectiveness of mechanical agitation, thermal agitation or capillerity in bringing the solid or liquid to be wetted quickly into intimate contact with the wetting solution often influences the speed of wetting more than the migration rate of the surfactant.

Micellar Solubilization of Emulsifiers

The spontaneous dissolutions of a normally insoluble substance by a relatively dilute solution of a surfactant are called Solubilization. The substance dissolved is referred to as the solubilizate and the surfactant as the ‘solubilizer’. There are no simple quantitative relationships between solubilizing power of a surfactant and the micellar or surface properties of its solutions. Solubilization is primarily a phenomenon of importance in dilute solutions. In more concentrated solutions it is sometimes difficult to distinguish between Solubilization and cosolvency, which is a term applied to a mixture of solvents that takes into solution a higher concentration of solute than would be expected from the sum of their individual Characteristics and Application of Emulsifiers solubilizing powers. Solubilization does not introduce another phase and solutions containing solubilized material are thermodynamically stable. It is a reproducible phenomenon but the rates of attainment of equilibrium differ greatly when approached from different directions.

Surfactant molecules or ions at concentrations above a minimum value characteristic of each solvent-solute system associate into aggregates called micelles. The term critical micelle concentration (CMC) is used to denote the concentration at which micelles start to form in a system comprising solvents, surfactants, possibly other solutes, and a defined physical environment. The CMC of surfactants in aqueous solutions depends on the structure of the compounds and the environment, but for many anionics at low electrolyte concentrations and room temperature it is close to 10-2 mols/litre; for non-ionics under comparable condition it is less, about 10-4 moles/litre. In many surfactants where the hydrophilic group is unchanged but the size of the hydrophobic group is increased, CMC values decrease with increasing size of the hydrophobe for both ionic and nonionic types. If the hydrophobic group is held constant, CMC values decrease with decreasing ethylene oxide content of non-ionic. Increasing the electrolyte concentration decreases CMC values for both anionics and non-ionics. The CMC of anionic micelles increases as the temperature increases, whereas the CMC of non-ionics decreases with the increase in temperature as would be expected from the cloud point phenomenon.

Solubilizations is a micellar phenomenon that occurs only at concentrations above the CMC. It is of considerable importance in non-aqueous applications of surfactants, particularly where water is the solubilizate. Typical applications are in dry cleaning solutions and engine lubricants. Essential oils, vitamins, cosmetic emollients, and textile mill processing oils are typical solubilizates in aqueous systems. Mixtures of surfactants are generally better solubilizers than the same surfactants used individually. Ionic—non-ionic com binations are especially effective.

Formulated Emulsifiers

Formulated surfactant products may be roughly divided into two major groups. One group is designed to perform ‘surfactant’ functions, e.g., cleaning, wetting, foaming, emulsifying and dispersing. The other group is designed to convey a non-surf actant functional ingredient to the point of use, e.g., a herbicide or insecticide toxicant, a textile mill processing oil. In addition to primary surfactants the components of formulated surfactant products may be classified as: (1) Non-surfactant functional additives, (2) Inert-fillers, and (3) Functional surfactant additives.

Non-surfactant Functional Additives

The art of surfactant formulation is directed to finding a combination of components that will be compatible and perform satisfactorily at the least cost to the user. Frequently, a surfactant is the most expensive component of a formulation and the mixture is designed so that less-expensive inorganic additives contribute as much as possible to the functional performance of the product. Hydrotropic agents are used to solubilize the ingredients in concentrated liquid surfactant formulations. The most common hydrotropes are the sodium or potassium salts of benzene, cumene, toluene or xylene sulfonates. These highly soluble solutes when present at relatively high concentrations, i.e., 5-15 wt percent, increase the solubility of sulfonate and sulfate surfactants in concentrated aqueous compositions. Solvents are also incorporated in surfactant products to obtain homogeneous concentrates, and also as functional additives. For example, ethanol is used as a solvent to clarify liquid shampoos. Pine oil and/or deodorized kerosene are often functional components of industrial and consumer detergent products.

Inert Fillers

Many surfactants are viscous liquids or low-melting solids that Characteristics and Application of Emulsifiers are difficult to handle as 100 per cent active materials. Sodium sulfate, clays or other inexpensive fillers are added as diluents and carriers to the concentrated surfactants to obtain free-flowing dry powders. Sometimes a portion of the sulfonating or sulfating reagent from the manufacturing process is neutralized and left in finished products as a filler.

Functional Surfactant Additives

Foam boosters, viscosity builders, and co-emulsifiers are the most important functional additives to surfactant formulations. The fatty acid alkanolamides and the alkylamine oxides are the outstanding examples of products in this category. They are effective surfactants on the basis of their own properties but one of their principal uses is to enhance the foaming and detergency of less-expensive materials e.g., LAS. In these applications, the performance of the mixture exceeds a projection based on the sum of the contributions of the components tested individually. The alkanolamides also increase the viscosity and emolliency of aqueous solutions. The lipophilic emulsifiers are another group of functional surfactant additives. Many of these materials are so hydrophobic that they have almost no utility when used alone, but in mixtures with hydrophilic emulsifiers they are exceedingly useful as co solvents, solubilizers, dispersants and emulsifiers.

Industrial Uses of Emulsifier

Agriculture

Emulsifiers are used in phosphate fertilizers to shorten manufacturing cycle and prevent caking during storage. In spray applications of herbicides, insecticides and fungicides, they are used in wetting, dispersing, and suspending of powdered pesticides and emulsification of pesticide solutions to promote wetting, spreading and penetration of the toxicant.

Building and Construction

In paving, they prevent stripping by improving the bond of asphalt to gravel and sand. Their use promote air entrainment in concrete for control of density, plasticity and insulating properties etc.

Elastomers and Plastics

In emulsion polymerization they effect the emulsification of monomers by solubilization of monomers and catalyst, which react in surfactant micelles. They also help in stabilization of latexes. In foamed polymers, they effect the introduction of air and control of cell size. In latex adhesive they promote wetting and thus improve bond strength. In plastic articles, they are used as antistatic agents and in plastic coating and laminating they are used as wetting agents.

Food and Beverages

In food processing plants, they are used for cleaning and sanitizing walls, floors and process equipment. They give improved removal of pesticide residues and aid in wax coating of fruits and vegetables. In bakery products and ice cream, they solubilize flavor oils, control consistency and retard staling. In beverages, they solubilize flavor oils. In crystallization of sugar, they improve washing and reduce processing time. In frying with cooking fats and oils, they prevent spattering due to superheating and sudden volatilization of water.

Industrial Cleaning

In miscellaneous cleaning, janitorial supplies and clothes, they are used for cleaning and sanitizing walls, floors, windows, vehicles, engines etc., and as detergents for laundry and dry cleaning. In descaling, they are used as wetting agents and corrosion inhibitors in acid cleaning of boiler tubes and heat exchanges. In wax strippers, they are used to improve wetting and penetrations of the old finish.

Leather

In leather industry, they are used as detergent and emulsifier in degreasing skins, to promote wetting and penetration in tanning; as emulsifiers in fat- liquoring of hides; to promote wetting, penetration and levelling in dyeing.

Metals

In concentration of ores, they are used for wetting and foaming i.e. collecting and frothing in ore flotation. In cutting and forming of metals, they are used for wetting, emulsification, lubrication, and corrosion inhibition in rolling oils, drawing lubricants, buffing and grinding compounds. In casting, they are used as mold release additives. In rust and scale removal, they are used for wetting, foaming and corrosion inhibition in pickling and electrolytic cleaning. In electroplating they are used for wetting and foaming in electrolytic plating baths.

Paper

In pulp treatment, they are used for derinsification, pitch dispersion and washing. In paper machine, they are used fordefoaming, felt washing, colour levelling and dispersing. In-calandering they are used for wetting and levelling in coating and colouring operations. In towels and pads, they are used for wetting to improve absorption of moisture. Industrial Uses of Emulsifier

Paints and Protective Coatings

In pigment preparation, they are used for flushing, i.e., promote preferential wetting by the paint vehicle; dispersing and wetting of the pigment during grinding. In latex paints, they are used to emulsify the oil or polymer, disperse the pigment, stabilize the latex, retard sedimentation and pigment separation, modify wetting and rheological properties. In waxes and polishes, they are used for emulsifying waxes, stabilize emulsions and wet substrates in finishes for floor and automobiles. Petroleum Production and Products They are used in drilling fluids to emulsify oils, disperse solids, and modify rheological properties of drilling and completion fluids for oil and gas wells. In mist drilling, they are used to convert intrusion water to foam in air drilling. In work over of producing wells, they are used to emulsify and disperse, sludge and sediment in clean out of wells; modify wetting of formation at producing zone. In producing wells, they are used to demulsify crude petroleum and inhibit corrosion of well, tubing, storage tanks and pipe lines. They are used for secondary recovery in flooding operations, to release crude oil from the formation surface, i.e., preferential wetting. Their application in refined petroleum products include as detergent, sludge dispersant and corrosion inhibitor in fuel oils, crank-case oils and turbine oils.

Textiles

In the preparation of fibres and filaments, they are used as detergent and emulsifier in raw-wool scouring; dispersant in viscose rayon spin baths; lubricant and antistat in spinning of hydrophobic filaments. In gray goods preparation, they are used for wetting and detergency in slashing and sizing formulations; wetting and detergency in kier boiling and bleaching of cotton, and carbonizing of wool; detergency in scouring piece goods; emulsification of processing oils. In dyeing and printing, they are used for wetting, penetration, solubilization, emulsification, dye leveling, detergency, and dispersion. In finishing of textiles, they are used for wetting and emulsification in finishing formulations, softening, lubricating and antistatic additives to finishes.

Biodegradable Emulsifiers and Water Pollution

The Heavy-duty household laundry detergents have been in use in largest amounts all over the world as the major products of the surfactant industry for the last forty-five years. The key ingredient that made this growth possible was ABS, an inexpensive alkylbenzene sulfonate in which the alkyl group was a highly branched propylene tetramer. Its continued discharge in rivers and lakes results in formation of excessive foams in rivers and lakes causing pollution of water. This fact became apparent for the first time in United States in 1950. Researches carried out later soon revealed that some types of synthetic detergents were more resistant than soap to degradation in sewage-treatment plants and attempts were made in 1963 in U.S. to replace ABS, the largest-volume synthetic surfactant, by LAS (Linear Alkylbenzene Sulphonate), a more biodegradable surfactant in a move to facilitate the degradation of detergent products in sewage plants.

Research soon established that degradation of surfactants by the bacteria in sewage-disposal plants is slower and less complete if the hydrophobic chain is branched rather than linear. In the early 1950’s no economically feasible technology was known for replacing ABS by a biodegradable substitute. The logical approach to the problem was replacement of the propylene tetramer by an equally inexpensive linear 12-carbon alkylation feedstock from a petrochemical source. However, technological breakthroughs in the early 1960’s opened up several possible routes to biodegradable alkylbenzene sulfonates.

(1) Separation of n-paraffins from kerosene feedstocks in molecular sieves (or alternatively by complexing with urea). Alkylation with the n-paraffins involves only conventional processing i.e., monochlorination followed by a Friedel-Crafts reaction or dehydro- Industrial Uses of Emulsifier halogenation and alkylation.

(2) Synthesis of linear 1-olefin or alcoholic detergent hydrophobes from ethylene is carried out by the Ziegler process using an aluminium catalyst. The trialkyl aluminium intermediate in this process can be oxidized to yield linear secondary alcohol suitable for detergent bases or catalytically decomposed to yield 1-olefins that can be used as alkylate feedstocks or hydrated to alcoholic hydrophobes.

(3) The 1-olefins obtained by cracking of petroleum waxes can also be used, either as alkylation feedstocks or hydrated to alcoholic detergent bases.

Biodegradation

Microorganisms have an inherent ability to convert organic matter, including surfactants, into new cell material, food and energy. The predominant mechanisms by which surfactant hydrophobes are attacked have been described as b-oxidation, methyl oxidation, and aromatic oxidation. In b-oxidation, the most important process, a linear hydrocarbon chain is oxidized at two carbons at a time; a branch in the chain interrupts the degradation. Methyl oxidation, which is less well understood, attacks terminal methyl groups. Aromatic oxidation proceeds through cat-echol (1,2-benzenediol) as an intermediate, which is cleaved to form an aliphatic dicarboxylic acid. The poly oxyethylene chains of non-ionics are probably degraded stepwise through a carboxylation and hydrolysis mechanism that splits glycol units from the chain. From a practical viewpoint, secondary and tertiary carbons in aliphatic chains and some phenolic nuclei slow the biodegradation process to rates that are unacceptable in present day sewage-treatment systems. Very large polyoxyethylene chains are also degraded slowly. In terms of products, carboxylic acids and salts, linear alcohol sulphates, sulfated fatty acids, sulfated fatty amides, sulfated esters, glycol esters, glycerol esters, and fatty alkanolamides are most readily biodegradable. The ethoxylated and sulfated linear alcohols, linear alkylbenzene sulphonates, and ethoxylated linear alcohols (upto about 70 wt per cent of polyoxyethylene) are readily biodegradable. The residual polyoxyethylene chains from high-polyethene-content non-ionics are not surface active and are not a problem in sewage systems at this time. Ethoxylated linear alkylphenols are more slowly biodegradable than aliphatic-based non-ionics. There is still some question about the acceptability of these products for all uses. Unacceptable products on the basis of biodegradability are the branched chain substituted alkylphenol derivatives; branched chain substituted alkylbenzene sulfonates, and the derivatives of branched-chain aliphatic alcohols, i.e., sulfates or sulfated ethyoxylates.

Development of methods to measure biodegradability of surfactants paralleled the development of biodegradable materials. Three methods out of the many screened have received widespread acceptance. Two of these, the river die-away method and shake flask methods. Biodegradation Test Methods are suitable for quick screening and/or routine use. The third, a semi continuous activated-sludge method, is more time consuming but is accurate and reproducible enough to serve as a reference method The determination of biological oxygen demand also provides useful data on biodegradation processes.

Anionic Surfactants

Introduction

The hydrophilic moiety in anionic surfactants is a polar group that is negatively charged in aqueous solutions or dispersions. In commercial products it is either a carboxylate, sulphonate, sulfate or phosphate group. In dilute alkaline solutions in soft water the solubilizing power of the sodium salts of the four anionic radicals is approximately equal and strong enough to balance the hydrophobic tendency of a 12-carbon saturated hydrocarbon group; the sulfate is actually a somewhat stronger solubilizer than the sulphonate. In neutral or acidic media or in the presence of heavy-metal ions, the solubilizing power of the carboxylate is markedly less than that of the other groups.

The ionic environment associated with anionic surfactants influences the properties of their solutions. Sodium and potassium salts are generally more soluble in water and less soluble in hydrocarbons. Conversely, the calcium, barium and magnesium salts are more compatible with hydrocarbon solvents and less so with water. Ammonium and amine salts, e.g., triethanolamine, improve the compatibility of anionics with water and hydrocarbons and are widely used in emulsification and detergent applications. Higher total ionic strengths are usually associated with lower solubilities of anionic surfactants. To offset this effect, the molecular weight of the hydrophobe is lower in products designed for use at high electrolyte concentrations. Micellar solubilization by anionics is markedly affected by total-ionic strength and also by the identity of the associated cations. The anionic surfactants can be divided into four groups according to their anionic groups—(1) Carboxylates, (2) Sulfonates, (3) Sulfates and Sulfated Products, (4) Phosphate Esters.

Carboxylates

Soaps and a small volume of aminocarboxylates are the only Anionic Surfactants commercial products in the carboxylate class of surfactants. Two types of aminocarboxylate surfactants, N-acy lsarcosinates and acylated protein hydrolysates, are produced in small quantities as specialties.

Both series of products are fatty acyl derivatives of aminocraboxylates. As compared to the corresponding soaps, the hydrophilic tendency of the amide linkages in these molecules is strong enough to significantly lessen inactivation of the carboxylate ions by the calcium and magnesium ions that are present in hard water.

Soap

For many years soap was the only surfactant produced commercially. Inspite of the development of many new surfactant types, it may be noted that soap possesses some desirable properties which are not found in many other surfactants. The sodium and potassium cocofatty acid soaps are unexcelled as lathering and cleansing agents in bar detergents for personal use in soft to medium hard water. The C14 to C18 fatty acid sodium soaps are effective laundry and industrial detergents in soft to medium hard hot water. Soaps, especially amine salts, are excellent emulsifiers, dispersants and solubilizing agents with a wide range of industrial uses. Soaps have an emollient action in contact with the skin and leave a soft feel on textile fabrics.

N-Acylsarcosinates

Sodium N-lauroylsarcosinate and the sodium N-acylsarcosinate derived from coconut fatty acids are soap like detergents with good lathering properties. They are principally used in dentifrices where it is claimed they also inactivate the enzymes that convert glucose to lactic acid in the mouth. N-Oleoy1-sarcosinate is used as a textile auxiliary and detergent. The N-acylsarcosinates are prepared by the condensation of a fatty acid chloride with sarcosine (i.e., N-methylglycine obtained from the reaction of methylamine, formal dehyde, and sodium cyanide) in alkaline aqueous solution.

Acylated Protein Hydrolysates

Fatty acyl aminocarboxylates are prepared from protein hydrolysates by acylation with fatty acid chlorides or by direct condensation with fatty acids. The commercial products are mixtures that vary in composition from acyl derivatives of polypeptides from incompletely hydrolyzed protein to mixtures of acylated amino acids derived from completely hydrolyzed protein. Collagen from leather scraps and low grade-hide glues is used as a source of protein. Derivatives of the incompletely hydrolyzed peptides have a great tolerance for hard water but their effective ness as surfactants is lower.

Sulfonates

The most effective structure for an anionic surfactant is a sulfonate of the general formula RSO3Na where R is a biodegradable hydrocarbon group in the surfactant molecular weight range. The R group can be alkyl or alkylarylene and the product can be a random mixture of isomers as long as it does not contain chain branching that interferes with biodegradability. The surface activity of the SO3 - group is not oversensitive to variations in the pH or to heavy metal ions and the C—S linkage is not susceptible to hydrolysis or oxidation under normal conditions of use.

Sulfonation processes on surfactant raw materials can usually be adjusted to increase or decrease slightly the degree of substitution of the solubilizing group on the hydrophobe. The average molecular weight of the hydrophobic bases can also be increased or decreased slightly. Minor adjustments in these two variables produce significant differences in performance. Sulfonates are usually obtained in the production process as free acids that can be neutralized to form alkali metal salts, alkaline earth metal salts, or amine salts; thus neutralization is another parameter for modification of properties. Manipulation of these variables leads to products with a multiplicity of combinations of properties from the same raw materials and production equipment.

The surfactants of commercial importance in this group are alkylbenzene sulfonates, petroleum sulfonates, di-alkyl sulfosuccinates, naphthalene sulfonates, N-acyl-N-alkyltaurates, 2-sulfo ethyl esters of fatty acids and olefin sulfonates.

Alkylbenzene Sulfonates

Linear dodecylbenzene sulfonates rank next to soaps in total usage. The sodium salt of linear dodecylbenzene sulfonate is commonly referred to as ‘LAS’. Linear dodecylbenzene sulfonic acid is called LAS acid, and salts other than sodium are named in an analogous manner, e.g., LAS salt. Commercial dodecylbenzene sulfonic acid is a light coloured, viscous liquid that is used almost entirely as an intermediate for the manufacture of alkalimetal, alkaline earth metal, and amine salts.

In comparisons of the performance of alkylbenzene sulfonates to that of aliphatic sulfonates, the effect of the benzene ring is often considered as approximately equivalent to three carbon atoms in an aliphatic chain.

Alkylbenzene sulfonic acids are strong organic acids and form essentially neutral alkalimetal salts that have a good solubility in aqueous solutions at use concentrations over the entire pH range.

These acids are not sensitive to precipitation by the natural hardness of the surface waters, but the alkaline earth metal salts are less water-soluble than the alkali metal and amine salts. The calcium salts are sufficiently soluble in hydrocarbons for use in these media. The alkylbenzene sulfonates are one of the most chemically stable types of surfactants. The sulfonic group is not susceptible to acidic or ammonium alkaline hydrolysis under normal conditions of storage or use. The compounds are stable to strong oxidising agents is aqueous solutions at use concentrations and are stable in carefully formulated products containing oxidizing agents.

The surface activity of unformulated, unbuilt dodecyl benzene sulfonates is sufficiently strong for the salts to be useful for their detersive, wetting, emulsifying, dispersing, and foaming properties, but they are not outstanding surfactants. The widespread usage of LAS stems from other factors, which include their low cost reproducible quality, adequate supply, light colour, low odour, and excellent response to formulation and builders. For example, LAS solutions are only average foamers but mixtures of LAS with alkanolamine or alkylamine oxide foam boasters have excellent foaming properties. Similarly, LAS performs well in built heavy-duty cleaning products where the wetting, foaming, emulsifying and dispersing properties of the surfactant component are as important as the detergency power. Amine salts of LAS & ABS acids are used in blends with other emulsifiers, particularly the non-ionic types, in emulsifiable concentrates of pesticides.

Petroleum Sulfonates

The petroleum sulfonates are the only large-volume class of surfactants that are used predominantly in non-aqueous systems. They are available as co products of the refining of certain petroleum fractions. They are usually grouped into two broad classes—water soluble types called ‘green soaps’; and oil soluble types called ‘mahogany soaps’ (which may also be soluble in water).

The green soaps are of little use. The mahogany soaps are valuable for their properties of solubilization, detergency, dispersion, emulsification, and corrosion inhibition. Their principal use is in lubricating oils for sludge dispersion, detergency, micellar solubilization of water, and corrosion inhibition. They are also widely used in other products for corrosion inhibition and emulsification. Alkylaromatic hydrocarbon sulfonates are the surfactant components in both product types. The green soaps contain a higher proportion of disulfonates than the mahogany sulfonates, which are principally monosul-fonates.

Dialkyl Sulfosuccinates

Sodium di (2-ethyl-hexyl) sulfosuccinate is the largest volume product of this group. It is now a widely used specialty surfactant.These sulfosuccinates as sodium salts are available as white, waxy, odourless solids or as concentrated colourless solutions. The di-C8 esters have the optimum solubility balance for use in tap water or aqueous solution with low inorganic salt content; lower alkyl esters are more effective in saline solutions. Sodium dialkyl sulfosuccinates are highly surface active but the susceptibility of the ester linkage to acidic or alkaline hydrolysis limits their usefulness. The products have strong wetting, rewetting, penetration and solubilization properties. The symmetrical diesters are produced by esterification of maleic anhydride using conventional technology-followed by addition of sodium bisulfite across the olefin linkage.

Naphthalene Sulfonates

Four series of specialty surfactants make up the widely used but relatively low-volume group naphthalene sulfonate products, viz., salts of alkylnaph thalene sulfonates; salts of sulfonated formaldehyde-naphthalene condensates; salts of naphthalene sulfonates; and salts of tetrahydronaphalene sulfonates.

In the concentrated dry form, most of the salts are almost odourless light-grey solids. They are readily and highly soluble in water. In fact, except for the nonyl derivatives, the naphthalene sulfonates are generally too soluble to be strongly surface active in soft water. The naphthalene sulfonates are stable to hydrolysis in acidic or alkaline media and are not sensitive to oxidation by strong oxidizing agents under use conditions.

The naphthalene sulfonates are used in many different applications as wetting and dispersing agents. Several members of the series are effective as stabilizing and suspending agents in disperse systems. Some of the products are useful for their solubilizing properties. Hard water does not adversely affect the surface activity of typical members of the series.

N-acyl-N-alkyl-taurates

The taurates are technically interesting as the only class of anionic surfactants with the combination of many advantages. They are stable against hydrolysis by acidic or alkaline media at use concentrations. They show no loss of performance in hard water. They have soap like biodegradability and residual feel on washed fabrics; and they have a molecular structure capable of yielding either strong wetting or strong detergent configurations. For example, the products RCON (R`) CH2CH2SO3Na are strong detergents when R = C11-C17 and R` = CH3 or C2H5, but are strong wetters when R = R` = C6-9. Relatively high raw material costs have held usage of the presently available N-acyl-N-alkyl taurates in the specialty category and have precluded the introduction of additional products with markedly different properties.

The commercial product N-Oleoyl-N-methyltaurate is marketed as a light-yellow solid at about 70 per cent assay or at lower concentrations in water as a light-coloured slurry, solution or gel. It is principally used in detergent applications with out builders. Foaming of the N-methyl derivatives is only moderate and is not readily improved by the usual foam builders; the N-cyclohexyl derivatives are low foaming detergents with good wetting power.

The production of sodium N-oleoyl-N-methyltaurate involves three chemical steps and yields average 95 percent or higher in each step.

2-Sulfoethyl Esters of Fatty Acids

These products, known commercially as b-sulfoesters, resemble closely in properties the fatty acids from which they are derived, but they have the advantage that hard water does not impair their performance. Only the sensitivity of the ester linkage to hydrolysis has prevented their widespread usage in consumer detergents. Hydrolysis is not a problem with detergents for personal use and the sodium salt of the 2-sulfoethyl ester of lauric acid, or similar coconut acid mixture, has found acceptance as the foaming and cleansing ingredient in synthetic detergent bars. The oleic acid analog is less foaming but is a good detergent with specialty uses in neutral or mildly alkaline systems.

The esters can be produced commercially from isethionate (obtained by the reaction of ethylene oxide with a concentrated solution of sodium bisulfite) and the fatty acid or acyl chloride. The reaction between the acyl chloride, which is a viscous liquid, and the powdered, anhydrous sodium isethionate is carried out in the absence of water or solvent under vacuum in a heavy-duty mixer. After the total charge is added to the reactor and brought to temperature, HCL is rapidly evolved, leaving the finally divided, light coloured product as the sodium salt.

Olefin Sulphonates

The increasing availability of relatively low cost linear 1-olefins in the C14 to C18 range has spurred research and commercial development of their sulfonate derivatives.

The 3- and 4-hydroxysulfonates which may amount to as much as half of the yield of sulfonated products are not very water-soluble but they are solubilized in the presence of the more soluble olefin sulfonate. The sulfonation mixture which is referred to as a-olefin sulfonate or AOS has detergency and foaming properties similar to C11-14 LAS. It is superior in performance to similar products made from internal straight chain olefins. Biodegradability of the AOS is slightly better than LAS; toxicity and skin irritation are slightly less.

Sulfates & Sulfated Products

The hydrophilic group in the surfactants falling in this group is SO3- attached through an oxygen atom to a carbon atom in the hydrophobic moiety. The additional oxygen makes the sulfate a stronger solubilizing group than the sulfonate but the C-O-S linkage of the sulfates is more easily hydrolyzed than the C-S linkage of the sulfonates. This susceptibility to hydrolysis, especially in acidic media, limits the utility of the sulfates. Solubilization of hydrophobes through the combination of ethoxylation and sulfation is frequently used to obtain the optimum solubility balance and also to utilize less expensive raw materials that cannot be solubilized sufficiently by sulfation alone, e.g., derived from tallow alcohols. The shift of the detergent industry to more biodegradable products has started a trend away from ethoxylated and sulfated alkylphenols and towards ethoxylated and sulfated aliphatic alcohols. The principal sub-groups of this class of surfactants are discussed below.

Alkyl Sulfates (Sulfated Alcohols)

The hydrophobes of this class of surfactants are obtained by reduction of fatty acids or esters of C12 to C20 hydrocarbon groups.

Secondary olefins sulfates are prepared by the addition of sulfuric acid to an olefin. These products have been marketed under the Teepol trademark of shell Oil Company. Sulfates obtained from the normal primary alcohols are similar in performance properties and in feel or emollient characteristics to the soaps of corresponding molecular weight. The branched chain alkyl sulfates are strong wetters. As the carbon chain length increases, the temperature needed to attain maximum detergent and wetting effects also increases. The stability of alkyl sulfates to hard water is excellent. In fact, magnesium lauryl sulfate forms voluminous foams with a low water content that is useful in rug shampoos where the soil is removed by vacuum pick up of the foam that is generated by vigorous brushing with a minimum volume of detergent solution. Sensitivity to hydrolysis in hot alkaline or acidic media is one of the principal disadvantages of the alkyl sulfates. Alkyl sulfates are high foaming detergents and strong wetters as well as effective emulsifiers and dispersants. Some of the products are used as leathering and cleansing agents in shampoos and dentifrices. Others are detergent and wetting agents for textile processing. Another use of the alkyl sulfates is as emulsifiers and dispersents in emulsion polymerization.

Lauryl sulfates can be prepared as the ammonium, sodium, potassium, magnesium, diethanolamine, and triethanolamine salts, which is indicative of the marked influence of the cations on the performance properties of this series of anionic surfactants.

Sulfated Natural Fats and Oils

The sulfated surfactants from natural fats and oils are obtained by the reaction of sulfuric acid which either-CH = CH-or-OH groups in natural fats and oils. The sulfate half-esters so obtained are neutralized with caustic soda in a later step.

Olive oil was the first oil to be sulfated to obtain a commercial surfactant other than soap. Later on, almost every potentially available animal, vegetable and fish oil was tried and it was found that ricinoleic acid which contains one hydroxyl group and one double bond, is a desirable constituent of an oil for sulfation. Oleic acid is also satisfactory. Esters of these acids can usually be sulfated with a minimum of hydrolysis. Polyunsaturated fatty acid moieties are undesirable components of glycerides for sulfation since the resulting surfactants are usually dark in colour and sensitive to oxidation.

Non- Ionic Surfactants

Introduction

A non-ionic surfactant, as the name implies, bears essentially no charge when dissolved or dispersed in aqueous media. The hydrophilic tendency in a non-ionic is due primarily to oxygen in the molecule, which hydrates by hydrogen bonding to water molecules. The strongest hydrophilic moieties in non-ionics are ether linkages and hydroxyl groups, but ester and amide linkages, which are also hydrophilic, are present in many non-ionics. The contribution of each oxygen to solubilization is weak and non-ionic molecules must contain a multiplicity of them in order to be water soluble. Nearly all of the unmodified polyol surfactants are lipophilic and they are frequently used as coemulsifiers in combinations with more hydrophilic surfactants. One advantage of the non-ionics is that they are compatible with ionic and amphoteric surfactants. Polyoxyethylene solubilization is the key to the substantial and continuing growth of the non-ionics. Since the polyoxyethylene group can be introduced into almost any organic compound that has reactive hydrogen, a wide range of organic substances can be solubilized by ethoxylation. Sub-division of the non-ionics into classes in accordance with the composition of the solubilizing groups is not as straight forward as with the ionic surfactants.

Polyoxyethylene Surfactants

The polyoxyethylene solubilized non-ionics are mainly used as textile auxiliaries. The solubility of these products depends on recurring ether linkages in a polyoxyethylene chain. A solubilized molecule contains many such chains and its hydrophilic tendency increases with the polyoxyethylene content of the molecule and 60-70 per cent by weight is required on most surfactant hydrophobes for complete miscibility with water at room temperature. A rule of thumb is that the hydrophilic strength of one ethylene oxide unit is approximately equal to the hydrophobic strength of one methylene unit. The water solubility of polyoxyethylene compounds decreases as the temperature increases, which is attributed to a decrease in the degree of hydration or to an increase in the size of the micelles. The temperature at which a second phase appears is called the cloud point, a practical solubility test that is not sensitive to concentration differences in the range between 0.5 to 10 per cent by weight. A minor proportion of anionic mixed with a non-ionic will often raise the cloud point to several degrees. Surface activity and performance efficiency of polyoxyethylene non-ionics is not adversely affected by hard water. High electrolyte concentrations in which sodium ions are the predominant component decrease the solubility of polyoxyethylene compounds by a salting out effect, whereas hydrochloric acid and calcium ions increase their solubility. Non-ionic surfactants solubilize iodine in aqueous solutions and lessen its toxicity to humans, but do not weaken its biocidal activity to the lower forms of life. The polyoxyethylene surfactants are moderate foamers and do not respond to the conventional foam boosters. They exhibit a foam maximum as a function of polyoxyethylene content. Low-foaming non-ionics are prepared by terminating the polyoxyethylene chain with a less soluble group, e.g., polypropylene oxide. A significant advantage of solubilization by means of polyoxyethylene is the capacity of attaining almost any hydrophilic/hydrophobic balance. A shortcoming is that the polyoxyethylene non-ionics tends to be liquids or low-melting waxes that are difficult to incorporate into dry, free-flowing powders. Flaked solid products containing a high ratio of polyoxyethylene are manufactured but their surface activity is low because they are too hydrophilic.

The conversion of an aliphatic alcohol, alkyl phenol, or fatty acid into a polyoxyethylene derivative can be divided into two steps - addition of ethylene oxide to the hydrophobe to form a monoadduct, and subsequent additions of ethylene oxide in a polymerization reaction. Ethoxylations of these hydrophobes are catalyzed by bases. Ethoxylation is normally carried out as a batch re- action although continuous reactors have been designed and operated. The hydrophobe and a solution of catalyst are charged into a reactor. Air and solvent for the catalyst are removed by agitating and heating under a vacuum, or purging with nitrogen or both. When the hydropbobe is at the reaction temperature, addition of ethylene oxide is started. The polymerization is exothermic (20 kcal/mole of ethylene oxide reacted) and the rate of ethylene oxide addition should not exceed the cooling capacity of the reactor since careful maintenance of the reaction temperature is essential for reproducible manufacture of products to specifications. The end point of ethylene oxide addition is often determined by testing the solubility of a sample for its cloud point in water, a salt solution, or a water solvent mixture. After the reaction is complete, the catalyst is neutralized and the product is discharged to storage or packaged. Polyoxyethylene solubilized non-ionics are poly-disperse mixtures of compounds that differ principally in the distribution of the polymer chain lengths. Their properties usually approximate those of the pure isomer represented by their average composition.

Ethoxylated Alkyl Phenols

Undiluted polyoxyethylated C8 to C12 alkyl phenols have a slight aromatic odour and vary from pale yellow to almost colourless. Products with low polyoxyethylene content are liquids and their viscosity increases with the content of combined ethylene oxide. High ratios of polyoxyethylene to hydrophobe are waxes. The specific gravity at room temperature increases with polyoxyethylene content from less than 1 to 1.2 Physical properties of the polyoxyethylated higher alkyl phenols e.g., dinonylphenol and hexadecylphenol, are similar to those of the C8 to C12 derivatives with the same wt. percentage of combined ethylene oxide.

The solubility in water of the ethoxylated alkyl phenols increases with the polyoxyethylene content. About 60 per cent by weight of polyoxyethylene is required for complete miscibility in cold water, and at above 75 per cent of polyoxyethylene the products do not cloud out at the boiling point. Water hardness does not adversely affect the surface activity of the products. The solubility of polyoxyethylene alkyl phenols in highly aliphatic mineral oils decreases faster with increasing polyoxyethylene content than the corresponding increase in solubility in water. Solubility in aromatic solvents and unsaturated triglycerides persists at higher mole ratios of combined ethylene oxide to hydrophobe. The excellent stability of the polyoxyethylene alkyl phenols against decomposition is demonstrated by their uses in formulations for acid cleaning of metals; in hot alkaline detergent systems; and in oil well drilling fluids for use at high bottom hole temperatures.

The maximum surface activity of the unformulated polyoxyethylene alkyl phenols in water hardness of 0—300 ppm is associated with polyoxyethylene proportions in the range of 50-75. per cent by wt. The optimum composition varies somewhat within, this range depending upon the property. Typical commercial products of polyoxyethylene alkyl phenols include, nonyl, octyl and doceyl phenoxy polyethylene oxy ethanols.Uses of polyxyethylene alkyl phenols as a function of polyoxyethylene content can be summarized as follows:

(1) Alkyl phenols containing 20-40 per cent polyoxyethylene are used as defbamers in surfactant solutions; detergent and/or dispersing agents in petroleum oils; coemulsifiers; intermediates for sulfation.

(2) Alkyl phenols containing 40-60 percent polyoxyethylene are used for oil-soluble detergents, dispersants, and emulsifiers; emulsifiers in emulsifiable concentrates of insecticides and herbicides; intermediates for sulfation.

(3) Alkyl phenols containing 60-70 per cent polyoxyethylene are used for textile detergents and processing auxiliaries; pitch control in manufacture of paper pulp; rewetting agents in paper towels; processing assistants in leather manufacture; detergents in industrial and consumer cleaning products; wetting agents in acid and alkaline cleaners; emulsifiers in emulsifiable concentrates of insecticides and herbicides.

(4) Alkyl phenols containing 70-80 per cent poly- oxyethylene are used for detergents and wetters at high temperature and/or electrolyte concentrations; emulsifiers for fats, oils and waxes; stabilizers for synthetic latexes; wetting and penetrating agents in caustic solutions.

(5) Alkyl phenols containing 80-95 per cent poly oxyethylene are used as stabilizers; synthetic latexes; emulsifiers for vinyl acetate and acrylate emulsion polymerization; dyeing and levelling assistants; lime soap dispersants.

Commercial ethoxylations of Alkyl phenols are always alkali-catalyzed but the reaction conditions, catalyst and catalyst concentration are chosen to obtain optimum properties for the intended use. All of the Alkyl phenol combines with one molecule of ethylene oxide to form the monoadduct before the build up of linear polyoxyethylene chains start, but by relatively minor variations in reaction conditions it is possible to obtain either a broad or narrow distribution of isomers at the same percentage content of polyoxyethylene. These differences are reflected in the properties of the products, particularly the solubilities. Another variant at constant gross composition is the percentage of polyglycol in the product, i.e., ethylene oxide polymer not combined with the Alkyl phenol.

Ethoxylated Aliphatic Alcohols

The ethoxylated aliphatic alcohols are costlier than the ethoxylated Alkyl phenols but due to recent change over to biodegradable products in the ensuing reformulation of industrial and consumer products, a shift in non-ionic types appears to be taking place with polyoxyethylene alcohols instead of polyoxyethylene linear Alkyl phenols replacing the branched chain Alkyl phenol derivatives in a significant fraction of the newer formulations. In the products of commerce which include oleyl-, cetyl-, stearyl-, lauryl-, tridecyl-, myristyl and tallow polyethylene oxy ethanols, the hydrophobes are generally mixtures of straight chain alcohols in the range from C12 to C18 and contain combined ethylene oxide in more ratios varying from 1 to 50 to hydrophobe. The undiluted products vary in physical form from liquids to many solids; viscosity in each homologous series increases as the polyoxyethylene content increases. The products have a slight odour characteristic of the hydrophobe that decreases as the polyethelene content increases. The liquids vary from pale yellow to almost colourless and the solids from yellow to white waxes; the products become lighter coloured as the polyoxyethylene content increases. Within each homologous series, the specific gravity at room temperature increases with the polyoxyethylene content from slightly less than 1 until it levels off a little under 1.2. Solubility of the alkylpoly (ethyleneoxy) ethanols in water increases with the ethylene oxide content; about 65-70 vol percent of polyethylene is required for complete miscibility at room temperature. The solubility of the polyoxyethylene derivatives of straight chain alcohols in aliphatic solvents is slightly greater than for the Alkyl phenols of comparable polyoxyethylene content. The water hardness does not impair the surface activity of the alkylpoly (ethyleneoxy) ethanols.

The functional properties and uses of the polyoxyethylene alcohols parallel very closely those of the polyoxyethylene Alkyl phenols. The usage of alkylpoly (ethyleneoxy) ethanols is divided more evenly among the available hydrophobes than with Alkyl phenols. This makes available a wider range of solubilities in water-insoluble liquids and contributes to the widespread use of the products as special-purpose emulsifiers. The Alkyl polyethyleneoxy ethanols have certain uses, such as textile-fibre lubrication, that are due to properties of the hydrophobe and for which the comparable polyoxyethylene Alkyl phenols are not applicable.

Ethoxylation processes and equipment for manufacture of the alkylpoly (ethyleneoxy) ethanols are similar to those described for the Alkyl phenols. However, the rate of reaction of primary alcohols with ethylene oxide is much faster than it is with Alkyl phenols; it is much closer to the rate at which the polyoxyethylene chains grows. Thus the build-up of polyoxyethylene polymer chain starts before all of the hydrophobe has reacted with one unit of ethylene oxide. The reactivity of alcohols with ethylene oxide varies in the order primary > secondary > tertiary. It is difficult to prepare polyoxyethylene derivatives of tertiary alcohols by direct reaction of the alcohol with ethylene oxide.

Carboxylic Esters

The carboxylic esters may be polyolsolubilized or poly oxyethylene solubilized or both for surfactant use. They are based on several different types of hydrophobes and accordingly, they are classified as — glycerol esters, polyethylene glycol esters, anhydrosorbitol esters, ethoxylated nhydrosorbitol esters, ethylene a and diethylene glycol es-ters, propanediol esters, ethoxylated natural fats and oils, carboxylic acid esters, silicone compounds etc.

Glycerol Esters

These are partial fatty acid esters either mono or diglycerides of fatty acids. The products of commerce are almost invariably mixtures of mono and diglycerides that also differ in respect to the positions of the hydroxyl group that are esterified. Typical products in the series include the mono and diglycerides of stearic, lauric, oleic and ricinoleic acids, and coconut, tallow, lard, cottonseed and safflower oils.

Mono and di-glycerol esters of the saturated fatty acids are light-coloured solids with melting points between 25 and 85°C. The 1-monoglycerides have higher melting points than the corresponding 2-monoglycerides. The glycerides of the unsaturated fatty acids are liquids at room temperature. The partial glycerol fatty esters have the characteristic odour of the fats from which they are derived. The polyol group of a monoglyceride is not strong enough as a hydrophilic moiety to carry even an easily solubilized acid like oleic into aqueous solution. Despite their lack of water solubility, the partial glycerol esters have commercially important and technically interesting surfactant uses.

The uses of mono- and diglycerides centre around applications involving emulsification, dispersion, suspension, solubilization and lubrication. One important use is as additives to foods and pharmaceuticals. Products intended for ingestion are prepared from edible fats. Mono and di-glycerides are widely used in bread, cakes, and other bakery products for their emulsifying, dispers ing and lubricating properties. They are also used in candies, ice creams, yeasts, butter, whipped tappings and icings. Flavour oils for carbonated beverages as well as bakery products are emulsified or solu-bilized by surfactant mixtures that include blends of mono- and diglycerides. Glycerol mono-stearate is used as an emulsifier and opacifier in cosmetic formulations. The partial glycerol esters are used as compounds of textile-mill processing and in lubricants, and softener formulations. The products also find application as emulsifiers, lubricants, and corrosion inhibitors in cutting, drawing and finishing of metal products. In the manufacture of paints and polymers, the mono- and diglycerides are used as emulsifiers, dispersants, suspending agents, and grinding oils.

Alcoholysis of fats with glycerol is the most important industrial method for the preparation of the partial fatty acid esters of glycerol. In this reaction, the fatty acid groups are redistributed between the original combined glycerol and the added glycerol without weight loss by heating at 180-250°C in the presence of an alkaline catalyst.

Polyethylene Glycol Esters

The polyoxy ethylene esters of fatty acids and of aliphatic carboxylic acids related to abietic acid comprise the polyethylene glycol series of surfactants. Properties and uses of these two groups of products differ markedly. Commercial polyoxyethylene fatty acid esters are mixtures that contain varying proportions of mono-esters, di-esters and polyglycol. The composition of the mixture can be forced toward the mono- or di-ester by the ratio of reactants and process of manufacture. The polyoxyethylene esters of fatty acids range in consistency from free flowing liquids to slurries to firm waxes.

Within a homologous series, the products change from liquids to waxes as the polyethylene content increases. Only low mole ratios of polyoxyethylene to unsaturated fatty acids or lower molecular weight acids yield liquid products. The odour of the products is characteristic of the fatty acid hydrophobe and decreases as the polyoxyethylene content increases. Odour and odour stability are important characteristics of these products because of their use in textile finishing. Colour stability is also important for the same reason. The oleates, for example, have good softening and lubricating properties but are precluded from some uses because of yellowing on exposure to air and heat.

The ester linkage is slightly hydrophilic and only about 60 wt. per cent of polyoxyethylene is required to solubilize the saturated fatty acids in water at room temperature. The surface activity of the fatty acid polyglycol esters, e.g., wetting and surface tension lowering, is in the useful range but less than for ethoxylated Alkyl phenols or aliphatic alcohols. The products are low foamers in aqueous solutions, which is advantageous for certain uses. Emulsification is a key property of this series of compounds and its importance is reflected in the wide range of lipophilic solubilities that are available in commercial products. Susceptibility to hydrolysis in hot acidic or alkaline solutions is their principal limitation. The fatty acid that is formed by acidic hydrolysis either separates as oil or forms an insoluble precipitate with the heavy-metal ions in hard water.

The Polyoxyethylene fatty acids are used extensively in the textile industry as emulsifiers for processing oils, antistatic agents, softeners, fibre lubricants, and detergents for neutral scouring operations. The products are also used as emulsifiers in cosmetic preparations, pesticide formulations etc.

Two methods are used commercially for manufacture of the polyoxyethylene acids. One is the alkali-catalyst reaction of a fatty acid with ethylene oxide. The other is esterification of a fatty acid with a preformed polyethylene glycol in the presence of an acid catalyst. Some manufacturers claim that the properties are different for products of the same gross composition as prepared by the two methods. However, the ethoxylation catalysts also catalyze trans-esterification and the products of direct ethoxylation approach closely those obtained by esterification if the manufacturing process is directed to this end. Deodourization and decolorization treatments are commonly incorporated in manufacturing processes.

The polyoxyethylene derivatives of the rosin acids are generally similar to the corresponding polyoxyethylene fatty acids in surfactant properties and processes of manufacture except that they are stable towards hydrolysis. The chemical stability of the polyoxyethylene tallates together with their characteristic low foam generation at use concentrations makes themuseful as components of consumer deter include the mono and diglycerides of stearic, lauric, oleic and ricinoleic acids, and coconut, tallow, lard, cottonseed and safflower oils.

Mono and di-glycerol esters of the saturated fatty acids are light-coloured solids with melting points between 25 and 85°C. The 1-monoglycerides have higher melting points than the corresponding 2-monoglycerides. The glycerides of the unsaturated fatty acids are liquids at room temperature. The partial glycerol fatty esters have the characteristic odour of the fats from which they are derived. The polyol group of a monoglyceride is not strong enough as a hydrophilic moiety to carry even an easily solubilized acid like oleic into aqueous solution. Despite their lack of water solubility, the partial glycerol esters have commercially important and technically interesting surfactant uses. The uses of mono and diglycerides centre around applications involving emulsification, dispersion, suspension, solubilization and lubrication. One important use is as additives to foods and pharmaceuticals. Products intended for ingestion are prepared from edible fats. Mono and di-glycerides are widely used in bread, cakes, and other bakery products for their emulsifying, dispersing and lubricating properties. They are also used in candies, ice creams, yeasts, butter, whipped tapings and icings. Flavour oils for carbonated beverages as well as bakery products are emulsified or solubilized by surfactant mixtures that include blends of mono- and diglycerides. Glycerol mono-stearate is used as an emulsifier and opacifier in cosmetic formulations. The partial glycerol esters are used as compounds of textile-mill processing and in lubricants, and softener formulations. The products also find application as emulsifiers, lubricants, and corrosion inhibitors in cutting, drawing and finishing of metal products. In the manufacture of paints and polymers, the mono-and diglycerides are used as emulsifiers, dispersants, suspending agents, and grinding oils.

Alcoholysis of fats with glycerol is the most important industrial method for the preparation of the partial fatty acid esters of glycerol. In this reaction, the fatty acid groups are redistributed between the original combined glycerol and the added glycerol without weight loss by heating at 180-250°C in the presence of an alkaline catalyst.

Anhydrosorbitol Esters

Fatty acid esters of anhydrosorbitol are the second largest class of polyol-solubilized surfactants. The important commercial products in the group are mono-, di- or triesters of sorbitan and fatty acids. Sorbitan is a mixture of anhydrosorbitols with the principal isomers being 1, 4-sorbitan and isosorbide.

The sorbitan oleates and the monolaurate are pale-yellow liquids. The palmitates and stearates are light-tan solids. Sorbitan is not a strong hydrophilic group and its derivatives are not water-soluble but they are soluble in a wide range of mineral and vegetable oils. The sorbitan esters are lipophilic emulsifiers, solubilizers, softeners and fibre lubricants. Many of the products have been approved for human ingestion and are widely used as emulsifiers and solubilizers in foods, beverages, and pharmaceuticals. Another important application is in synthetic fibre manufacture and textile processing as antistats, fibre lubricants, softeners, and emulsifiers of textile-mill processing oils. The sorbitan esters are also widely used as emulsifiers in cosmetic products.

The anhydrosorbitol esters are prepared commercially by direct esterification of sorbitol with a fatty acid in the presence of an acidic-catalyst at temperatures in the range 225-250 °C. Internal ether formation as well as esterification takes place under these conditions. The commercial products of importance in this group include the mono and trilaurates, oleates, stearates and palmitates.

Ethoxylated Anhydrosorbitol Esters

Ethoxylation of the sorbitan fatty acid esters leads to a series of more hydrophilic surfactants. They are widely used as emulsifiers, antistats, softeners, fibre lubricants and solubilizers. The ethoxylated sorbitan esters are often used as co-emulsifiers with the unethoxylated sorbitan fatty acid esters or the glycerol partial fatty acid esters. Sorbitan fatty acid esters can be reacted with ethylene oxide in the presence of an alkaline catalyst at temperatures from 130 to 170°C to produce the ethoxylated derivatives.

Glycol Esters of Fatty Acids

The ethylene glycol, diethylene glycol, and 1, 2-propanediol esters of fatty acids are widely used surfactants. The commercial products are mixtures of mono and diesters even though the stated composition usually refers only to the principal component. The mono and dilaurates and oleates of ethyleneglycol, diethylene glycol, and propylene glycol are liquids. Stearates of these glycols are solids. The glycol esters are strongly lipophilic emulsifiers, opacifiers, and plasticizers that are normally formulated in combination with hydrophilic emulsifiers. They are used as components of cosmetic preparations. The monoesters of glycols can be manufactured by the alkali-catalyzed reaction of ethylene or propylene oxide with fatty acids. Mono and diesters are also prepared by esterification of a fatty acid with a glycol.

Ethoxylated Natural Fats, Oils and Waxes

The products of commercial importance in this group of surfactants are chiefly ethoxylated castor oil and ethoxylated lanolin derivatives.

Castor oil is a triglyceride with a high content of esterified ricinoleic acid. Its ethoxylation in the presence of an alkaline catalyst to a polyoxyethylene content of 60-70 wt. per cent yields water-soluble surfactants. The composition of the ethoxylated derivatives is more complex than might be expected. The ethoxylates are yellow-to-amber viscous liquids with specific gravities slightly greater than 1.0 at room temperature. Ethoxylated castor oils are hydrophilic emulsifiers, dispersants, and lubricants. They are used as processing assistants and finishing agents in the manufacture of paper, leather and textile products. Other uses are in emulsion polymerizations, paints, polishes, and cosmetic products. Skin irritation and phytotoxicity are usually low.

Lanolin alcohols are derived from the fat that is stripped from raw wool. They are a mixture of cholesterol, isocholesterol, and other higher alcohols. Lanolin alcohols purified by bleaching, solvent extraction, crystallization, or molecular distillations are ethoxylated to yield non-ionic emulsifiers. The mole ratios of ethylene oxide to alcohols that are offered commercially represent a full series of lipophilic and hydrophilic products. Their largest use is as emulsifiers in cosmetic preparations.

Sulfonated Oils

Historical Background

In the early days of textile industry, soap in one form or the other was the only cleansing, wetting, emulsifying and dispersing agent available. Its inability to stand hard water and acid led to the development of a product possessing the valuable properties of soap without its defects. The first successful attempt towards this was of Fremy, a Frenchman who studied the effect of concentrated sulfuric acid on olive oil, but it was A. Runge who first prepared sulfated olive oil by first reacting the olive oil with concentrated-sulfuric acid and then neutralized the reaction product with cold caustic potash solution. The product was an oily, water dispersible substance. A British patent was granted to Mercer, in 1847, for sulfonating olive oil, which was to be used in dyeing madder Turkey Reds. Since then, many different oils have been sulfated e.g., rapeseed oil, cottonseed oil, castor oil, groundnut oil and corn oil etc, and neutralized with alkalies. The term Turkey Red Oil’ has since been used for sulfonated castor oil.

The reaction between any oil and sulfuric acid, takes place in several ways, depending on the temperature, the intimacy with which the materials are brought into contact, and the time. The major reaction results in a sulfated rather than a sulfonated product. With ordinary oils, sulfation occurs at the double bonds of the fatty acids, resulting in triolein hydrogen sulfate. Sulfuric acid reacts with the hydroxyl group of the ricinoleyl (12-hydroxy-9-octadecenoic acid) radical of castor oil to form the sulfate.

These products when used in the last stage of wet processing of textiles impart the fabric a desirable softness or fullness and thus by the end of the 19th century the use of sulfated oils as an important textile auxiliary chemical and finishing agent became well established. The sulfated oils of the late nineteenth century were usually only partially sulfated and thus contained a proportion of unchanged fatty glycerides. Sulfated oils in which a large part of the glycerides had been hydrolysed to the fatty acids possessed all the faults of the fatty acids themselves, particularly their sensitivity to hard water and to acidic conditions. These defects led to the production (in the 1920—35 period) of so-called ‘highly sulfonated oils’.

Chemistry of Sulfation and Sulfonation

In sulfonated oils the strongly polar sulfo-group appears in the centre or thereabouts of a C18 alkyl chain and the specific properties of the products, although useful, are not so highly developed as in compounds in which the polar group terminates a long alkyl or acyl carbon chain. Hence for many purposes, the ‘sulfonated oils’ are being replaced by one or other of the more recent preparations.

The oils have, therefore, not been sulfonated, but sulfated, and the term ‘sulfonated oil’ does not convey an accurate picture of the process. Other side reactions proceed concurrently during either of the above two main actions. The sulfate group is fairly easily removed in an acid medium in presence of moisture and consequently the final product contains a certain proportion of hydroxy acids. Further, estolides and possibly other anhydride like compounds are produced during the reaction by elimination of water between the alcoholic group of one molecule of sulfated fatty acid and the carboxyl (or possibly sulfate) groups of another. Finally, in the case of sulfation of oils, the sulfated derivatives have the typical constitution of fat-splitting (hydrolytic) agents, and considerable production of free fatty acid, sulfated or otherwise, from neutral oil, usually takes place during their manufacture.

On the other hand, production of true sulfonic derivatives, in place of, or accompanying the sulfated products, may occur if the action is allowed to take place under strongly dehydrating conditions and, especially, if fuming sulfuric acid (oleum), sulfur trioxide, or chlorosulfonic acid is used in place of sulfuric acid as the sulfonating agent. In these cases the reaction probably takes a course such as: The acid sulfate group in the complex formed is comparatively easily hydrolyzed during subsequent washing of the product with water, and true (hydroxy)-sulfonic acids, -CH (SO3H) CH(OH)- ,and their condensation products, are present in the material finally obtained. These compounds will, of course, be completely stable in so far as the direct attachment of the sulfonic group, SO3H, to a carbon atom is concerned, whereas the hydrogen sulfate groups of turkey red and the ordinary ‘sulfonated’ oils and oleins are liable to hydrolyse in presence of water of dilute acid, yielding free sulfuric acid and a neutral hydroxy fatty compound ; as between the true fatty (hydroxy) sulfonates and the unhydrolysed sulfate- derivatives of the type of turkey red oil, there is probably little to choose on the score of relative efficiency. Claims that the true sulfonates are more effective textile assistants may in reality be based upon their greater stability, which is due to their incapacity to loose the polar sulfo-acid group by hydrolytic action.

Applications of Sulfonated Oils

Sulfonated oils and fats fulfil many vital needs in the textile processing industry. Their earliest use as assistants in the dyeing of fabrics still remains one of their dominant functions in this field. They are characterized by their dispersing properties, surface activity and colloidal nature. These characteristics suit them admirably to the dyeing process. Sulfated castor oil is used in dyeing cotton and rayon fabrics with direct dyeing colours to facilitate penetration and ensure level dyeing. It is also used as dispersing and penetrating agent in the application of vat and naphthol colours. Sulfated oil containing high organically combined sulfate contents (5 to 7 percent) is most suitable for these uses as they generally possess greater penetrating power and exhibit high tolerance to electrolyte. Excessive sulfation, however, reduces the softening properties of sulfated oils and destroys the natural antioxidant, which helps to prevent rancidity. For this reason, finishing oils should be prepared to contain a minimum amount of organically combined sulfate consistent with good solubility and stability.

Sulfated oils and fats are probably consumed in greater quantities in finishing operation. Here they are incorporated into the fabric in the final wet-process for the purpose of enhancing its appearance and feel. Sulfated olive oil is now almost universally used as a softener on cotton and rayon fabrics where extreme silkiness and drape are desired. Sulfated olive and castor oils are used as lubricants for soaping and as tinting oil ingredients for natural silk and rayon. In both cases the sulfated oil is generally combined with gelatin and dispersed in water, as is the case when they are used in warp sizing formulation. Sulfated oils are sometimes combined with highly purified mineral oils to impart added surface lubrication and ‘sleekness’ to the fabric.

Sulfated tallow is commonly used for moderate softening effects and to add body or apparent weight to the fabric. For additional body and firmness, the sulfated tallows are sometimes combined with gums and starches. They may also be combined with polyoxyethylene condensate and salt or an alkylolamide condensate and alkali for the dual purpose of scouring and fulling of woollen fabrics. Sulfated tallow has proved to be an excellent emulsifying agent with all types of waxes and thus it has been possible to formulate many types of wax emulsions based on sulfated tallow. These wax emulsions are applied to cotton and rayon to produce an effect of ‘fullness’ and ‘body’, enhancing the lustre of calendered fabric’s surface.

One of the greatest use of sulfated tallow is in the warp sizing of cotton yarns where it is generally used in conjunction with gums or starches. Here it serves the dual function of plasticizing the size film and lubricating the yarn to reduce the frictional resistance in the loom. Mixtures of sulfated oils with white mineral oils impart excellent softness and lubrication and are quite commonly used on high quality cotton rayon fabrics. The presence of high grade mineral oils improve materially the heat and ageing stability of sulfated finishing oils.

Pine oil, xylol and cresylic acid are mixed with sulfated oils to improve their penetrating and detergency power. They are then used as kier boiling assistants, general scouring agents, and agents for removal of grease and tar stains.

Manufacture of Sulfonated Oils

Fatty oils are sulfated with concentrated sulfuric acid and sulfonated with sulfur trioxide. Both processes are of semi-batch type and the sulfur trioxide process gives a product containing a much higher combined SO3.

Sulfation

The sulfation is carried out in a lead lined vessel, jacketted or fitted with cooling coils and agitator. The reactor is fed with appropriate amounts of the oil and about 25 to 50 per cent on the basis of the amount of oil charged, cold and concentrated sulfuric acid is added to the oil with constant stirring. The circulation of cooling water is started simultaneously. The rate of addition of acid must be so adjusted that the temperature does not exceed 35°C. With olive or rapeseed a some-what lower temperature is safer and the less saturated oil, e.g., fish, linseed, soyabean etc are better treated at or below 10°C to avoid undesirable results. After the addition of all the acid, cooling and agitation are continued for some more time in order to complete the reaction. The mixture is left overnight and again stirred next day. The reaction is considered complete when a sample of the product completely solubilizes in a given amount of water depending upon the degree of sulfation desired.

The free sulfuric acid is removed by adding a quantity of cold water equal in weight to the reaction mixture and allowing it to settle overnight. The aqueous acid layer is then drawn off and the oil is either washed several times with sodium chloride solution or treated with dilute caustic soda solution until the mixture is neutral to Congo red paper. Exacting control during washing and neutralizing step is essential. Conditions occur during this operation, which tend to promote desulfation and hydrolysis resulting in an end product low in organic sulfur trioxide and high in free fatty acids. When it is desired to prevent splitting to the greatest possible extent, washing is done with sodium sulfate solution instead of salt solution. Washing and neutralization temperature are kept low, time of reaction short, and pH adjustment accurate. After neutralization the oil is allowed to settle out from the excess of the solution of inorganic salts. The finished product usually contains about 35 per cent water. Optimum conditions for individual oil should be determined by experiments. Monel and nickel clad steel are excellent materials of construction for the reactor but since they are costly, lead-lined steel is most often used.

Sulfonation

The process development work for sulfonation with SO3 was Sulfonated Oils carried out by flask sulfonation. In a typical laboratory batch reaction, castor oil is charged to a reaction flask and SO3 diluted to 4 per cent by volume with dry air is introduced below the surface while agitating vigorously. The reaction temperature is maintained between 45—50°C and the reaction time is between 20-25 minutes. After all of the SO3 has been added, the reaction mass is drowned in 15 per cent sodium hydroxide. The resulting product contains about 25 percent water and has 8 per cent organically combined SO3 based on 100 per cent solids. It also displays excellent water solubility at all concentrations.

Results obtained in the laboratory sulfonation can generally be duplicated in the pilot plant, and product quality is often improved because of better heat removal and SO3 distribution in the continuous reactor. The continuous reactor used for this work consists of a set of vertically mounted, water jacketted, stainless steel concentric cylinders, divided into three sections: the distribution section, the reaction section and the separation section. The main function of the distribution section is to direct flow so as to deposit, continuously an even film of oil to the inner and outer walls of the reaction section. This is accomplished by pumping the castor oil through small peripheral shots in the distributor.

The SO3/air mixture is introduced above the distributor and passes through the annular space between the concentric cylinders in such a way that contact is made with the castor oil, just at the point where the film is developed. In the upper part of the reaction section, the gas stream containing the initial concentration of SO3 contacts the unreacted castor oil. As the gas stream and the organic film continue to move together down the reactor waIls, SO3 is absorbed by the liquid organic phase reacting with it so that at the end of the reaction section SO3 remaining in the gas phase approaches zero concentration. Virtually all the SO3 in the entering gas stream is absorbed by the organic film and converted to organic sulfate or sulfonate. The film is in intimate contact with the water jacketed reactor walls and movement in the liquid film generated by differential velocity of the gas stream provides an efficient heat removal and excellent temperature control. It also minimizes localized overheating. The reaction mass then passes into the separation section where acid product is withdrawn for subsequent processing and spent gas is separated and exhausted to atmosphere through a suitable mist filter.

A -batch-SO3/air system, on the other hand, would operate in a manner similar to that used in the continuous system except that the continuous reactor would be replaced by a stainless steel reaction vessel, equipped with a turbine agitator and circulating pump and a heat exchanger.

In India sulfuric acid is generally used for sulfation of oils and thus most of the products marketed are sulfated oils rather than sulfonated oils, although they are marketed under the latter name. They contain about 30, 50 and 75 percent sulfated organic matter and free oil; the rest is mainly water.

Sulfation of Individual Oils

This product was at one time manufactured according to a German process as practiced by M/s.Bohme Felt Chemie. The product was marketed as ‘A Virol K M’. In this process 200 kg. sulfuric acid is slowly added into 1600 kg. castor oil with continuous stirring in about four and a half hours. The temperature of the mixture is maintained between 25—30°C by circulating water in cooling coils and/or jacket. After stirring for 1½ hour further, 130 kg. of sulfuric acid is added slowly and With continuous stirring in over 3 hours and the batch is allowed to stand for 13 hours without stirring. Finally, a further quantity 50 kg. of sulfuric acid is added in about 1 hour and stirring is continued for another hour. The batch is then neutralized as quickly as possible by stirring with 40°Be caustic soda (860 kg.). The temperature rises 90 to 100°C. The product should now show an acid reaction to phenolphthalein. Live steam is now passed in for 1/2 hour. After standing overnight, the aqueous salt layer is run off. The product is settled for 2 weeks, the aqueous layer is run off and it is then standardized by addition of requisite quantity of water.

Alkylolamides

Introduction

Alkylolamides are condensates of alkylolamines and fatty acids and are generally referred to as foam boosters or additives. Their use in detergent formulation goes a long way towards solving the problems of stabilization, improvement and creaming of lather which are so important to the success of compounded detergents. They can be used as detergents in their own right, but probably their main outlet is as ingredients in shampoo and liquid and powder detergent production.

The condensates of commercial interest can be divided into three classes :

(1) Products from the reaction of one mole of a monoalkylolamine and one mole of fatty acid.

(2) Products of reaction of one mole of a dialkylolamine with one mole of fatty acid.

(3) Condensation products of more than one mole of a -dialkylolamine with one mole of fatty acid.

The products of the class (1) with free fatty acid contents in the range of 5-10 per cent, are oily light brown liquids which are soluble in water and are quite good detergents particularly for cleaning hard surfaces, walls, tiles, floors etc. These products can be used in the formulation of liquid cleaners, and the following formula has been suggested.

This type of formulation is advocated for packing in mild steel drums for sale to hospitals, institutions, bakeries etc.

The products of the class (2) with low free fatty acid contents are used as foam boosters, particularly in the formulation of liquid cleaners. They also act as solubilizing agents for alkyaryl sulfonates and sodium lauryl sulfates, depressing the cloud points of mixtures and helping to ensure that no separation of active matter occurs at low temperatures. These products are also used to a more limited extent as additives for powder detergents; they are incorporated by spraying in the molten state on to spray-dried or physically mixed powders.

The monoalkylolamine derivatives find their major outlet as builders for all-purpose spray-dried powder detergents, where they are normally used at the level of 1—3 per cent. The range of useful additives is wide, but can be limited to some extent by economic considerations. In the choice of additive for any particular formulation the following points must be considered:

(a) Does the additive have the desired foam boosting properties when added at the desired economic level ?

(b) Are the raw materials available at a reasonable and stable price?

(c) Can the additive be made consistently or does it suffer batch-to-batch variation, which impairs its properties.

(d) Is it compatible with other ingredients in formula e.g., if used with a liquid product, can it be sufficiently solubilized, together with the other solution ?

(e) Can it be easily incorporated at the right concentration in the powder—e.g., can it be sprayed evenly on to the powder, will it be stable at spray-drying temperatures, or will it result in a sticky powder and tend to bleed out ?

(/) Is it stable under long-term storage conditions or will it turn rancid or affect the perfume in anyway ?

(g) Has it any disadvantages in use—e.g., does it leave streaks on glasses washed in the detergent solution?

The time taken between laboratory trials and launching a detergent powder on a commercial scale may be anything from