Manufacturing processes anionic surfactants

Since sulfur-based S03/air is becoming the predominant route for the manufacture of anionic surfactants, little attention will be paid to other, less versatile processes in this chapter. 

At approximately the same time, a further process for the manufacture of anionic surfactants of the sulfonate type, namely the olefinesulfonates, became of interest. This process starts from a-olefines obtained by cracking of higher hydrocarbons. In this process, the olefine is reacted with SO3 for a short time in a thin-layer reactor. Alkenesulfonates and hydroxyalkanesulfonates are formed [18]. 

Not only the linear Cl0-Cl8 a-olefins but also the linear C10-Cl8 olefins with internal double bonds, the so-called -v /-olefins, are of great importance in surfactant chemistry, n-a-Olefins and n-y-olefins have the same suitability for the manufacture of linear alkylbenzenes, the most important synthetic anionic surfactants, by alkylation of benzene. Nowadays medium molecular weight n- /-olefins are industrially produced by two processes the catalytic dehydrogenation of the corresponding n-alkanes [4,28] and the cometathesis of low and high molecular weight n-v /-olefins, obtained by double-bond isomerization of the isomeric n-a-olefins [29]. 

In the manufacture of coating materials, paints, varnishes, lacquers, dyestuff pigments, binding materials, and binders, surfactants are of great importance. Most of the systems used in these fields are dispersed. Therefore surfactants can accelerate the preparations of dispersions and improve their stability. For rewetting processes, like the so-called flush process, besides other anionic surfactants sulfosuccinates are also used. 

The primary application of these alcohols is the manufacture of anionic or nonionic surfactants for personal cleansing products, most of which end up in your wastewater treatment plants and rivers. Microorganisms don t chew up branch-chain surfactants as well as they do the straight ones. It used to be, for example that the surfactant based on the sodium salt of dodecyl benzene sulfonate, a 12-carbon branch chained anionic surfactant, was found to be slowing, down water treatment processes. Dodecyl alcohol as a raw material for these surfactants has been largely replaced by laurel alcohol, a 12-carbon straight-chain, linear alcohol. If you look at the bottle next time you shampoo your hair and rinse, you ll see sulfonates based on laurel alcohol listed, but none based on dodecyl. 

About 4 percent of 2-ethylhexanol domestic demand is consumed in the manufacture of di-2-ethylhexyl sulfosuccinate -a general purpose anionic surfactant used in textile processing. 

When specifying an anionic surfactant for an application, it is important to understand how the composition of the raw material (especially that of the hydrophobe) influences the performance of the surfactant and the properties of the formulated product. In looking at the properties of each surfactant type, the basic chemistry will be considered together with sources of hydrophobe and the manufacturing process used to functionalise them. How the composition of the surfactant affects its performance and physical properties will be examined together with how these properties lead to the applications of the surfactant. 

Fast reaction of Ca in solution with anionic surfactants and inorganic components (silicate, carbonate) leads to undesirable non-soluble products in the washing process. The rate of exchange (rate of Ca eoncentration decrease in solution-depletion rate) ought to be competitive with these reactions. A typical high quality manufacturing standard demands, from 3 mM Ca solution (16.8°d) the following depletion rate ... 

The major use of vulcanizing latex adhesives is in the manufacture of textiles, rugs and carpets, and closely allied products such as rubberized hair. As in many other latex applications, ultraaccelerators are used to effect vulcanization. The materials used must be stable in alkaline dispersions, although they need not be active, since if the alkali is ammonia it will normally be removed early in the drying/vulcanization process. The vulcanization ingredients, sulfur, zinc oxide, and the insoluble accelerators must be added as dispersions in water, and these are conveniently prepared at 50% solids and stabilized by an anionic surfactant. Such dispersions may be made by ball-milling or may be easily purchased premade from specialist suppliers. Soluble accelerators can be added as solutions directly to stabilized latex, but the solutions have a much more limited life than do dispersions. 

The free-radical addition of TFE to pentafluoroethyl iodide yields a mixture of perfluoroalkyl iodides with even-numbered fluorinated carbon chains. This is the process used to commercially manufacture the initial raw material for the fluorotelomer -based family of fluorinated substances (Fig. 3) [2, 17]. Telomeri-zation may also be used to make terminal iso- or methyl branched and/or odd number fluorinated carbon perfluoroalkyl iodides as well [2]. The process of TFE telomerization can be manipulated by controlling the process variables, reactant ratios, catalysts, etc. to obtain the desired mixture of perfluoroalkyl iodides, which can be further purified by distillation. While perfluoroalkyl iodides can be directly hydrolyzed to perfluoroalkyl carboxylate salts [29, 30], the addition of ethylene gives a more versatile synthesis intermediate, fluorotelomer iodides. These primary alkyl iodides can be transformed to alcohols, sulfonyl chlorides, olefins, thiols, (meth)acrylates, and from these into many types of fluorinated surfactants [3] (Fig. 3). The fluorotelomer-based fluorinated surfactants range includes noiuonics, anionics, cationics, amphoterics, and polymeric amphophiles. 

PFCA salts (e.g., the sodium and ammonium salts) are an industrially important class of anionic PFCA surfactants. Electrochemical fluorination has been employed to manufacture APFO, an emulsifier used in the production of fluoropolymers and other PFCAs. Hydrolysis of the acid fluorides obtained by electrochemical fluorination results either in the free carboxylic acids or the respective salts. A major problem associated with the hydrolysis of PFCA fluorides is the presence of HF from the electrochemical fluorination and the hydrolysis of the PFCA fluorides with water." The technical process of isolating fluoride-free PFCA derivatives has, therefore, been optimized to reduce the fluoride content of the final product to trace amounts. An example of such a process is shown in Figure 18.6. °... 

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