Fatty acids synthetic, surfactants from

The natural fatty acid soaps derived from tallow (animal fat) continue to form an important group of surfactants even though their portion of the market has tended to decline relative to the synthetics. The salts of the coconut oil acids and some acids derived from oilseed sources, on the other hand, have found increased use in hard-water applications and liquid hand soaps, where high soap concentrations are desired. The improved performance of coconut oil soaps probably results from their higher content of the lower-molecular-weight C12 and C14 acids (60-70%) versus the tallow soaps (80-95% C14 or greater). 

To overcome these difficulties, drilling fluids are treated with a variety of mud lubricants available from various suppHers. They are mostly general-purpose, low toxicity, nonfluorescent types that are blends of several anionic or nonionic surfactants and products such as glycols and glycerols, fatty acid esters, synthetic hydrocarbons, and vegetable oil derivatives. Extreme pressure lubricants containing sulfurized or sulfonated derivatives of natural fatty acid products or petroleum-base hydrocarbons can be quite toxic to marine life and are rarely used for environmental reasons. Diesel and mineral oils were once used as lubricants at levels of 3 to 10 vol % but this practice has been curtailed significantly for environmental reasons. 

The solubihty characteristics of sodium acyl isethionates allow them to be used in synthetic detergent (syndet) bars. Complex blends of an isethionate and various soaps, free fatty acids, and small amounts of other surfactants reportedly are essentially nonirritant skin cleansers (66). As a rule, the more detersive surfactants, for example alkyl sulfates, a-olefin sulfonates, and alkylaryl sulfonates, are used in limited amounts in skin cleansers. Most skin cleansers are compounded to leave an emollient residue on the skin after rinsing with water. Free fatty acids, alkyl betaines, and some compatible cationic or quaternary compounds have been found to be especially useful. A mildly acidic environment on the skin helps control the growth of resident microbial species. Detergent-based skin cleansers can be formulated with abrasives to remove scaly or hard-to-remove materials from the skin. 

The alkali-metal salts of fatty acids - soaps - are the oldest synthetic surfactants and they have been prepared in various forms and in varying purity since pre-historic times. The technology has progressed from boiling animal fats with wood ash to an ultra-efficient high volume process, with a very extensive knowledge and literature base. 

Ion-pair extraction of an anionic surfactant with a cationic dye such as methylene blue from water into oil is often used for the quantitative analysis of the surfactant in water [57,58]. The surfactant concentration in water is then determined as the dye concentration in the oil or water phase by conventional absorption spectroscopy. Synthetic surfactants such as sulfates and sulfonates completely dissociate in water even at low pH. On the other hand, the association of fatty acid salts (traditional soaps) with H" " depends on the pH. Therefore, the quantitative analysis of surfactants in water is performed by the ion-pair extraction at various pHs. Although quantitative analysis and thermodynamic studies have been already reported for the anionic surfactant/cationic dye extraction, kinetic analysis of the ion-pair extraction has been rarely reported and the extraction mechanism is not discussed in detail. In this section, we describe the kinetic analysis of the extraction of a dodecyl sulfate anion with methylene blue as a typical example using the single microdroplet manipulation and microabsorption methods [59]. In particular, the pH dependence of the ion-pair extraction is discussed. 

Oils and fats have been important throughout human history not only for food, but also as lubricants, polishes, ointments, and fuel. The reaction of oils and fats with alkali (saponification) produces soap (salts of fatty acids) and glycerin. This chemical process was known to the Romans and continues to be of significant commercial importance. Today, tens of thousands of tons of soap are produced annually from tallow and plant oils. Tallow is a by-product of the meat industry, while the principal plant oils are dependent on extensive plantations—palm and palm kernel oils from Indonesia, Malaysia, and India, and coconut oil from the Philippines and Brazil. Twentieth-century chemists designed more effective synthetic, crude-oil-based surface-active agents (surfactants, e.g., sodium linearalkylbenzene-sulfonate or LAS) for fabric, household, and industrial cleaning applications, and specialty surfactants to meet the needs of consumer products industry such as milder skin and hair cleansers. 

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