Alkyl sulphates Applications

Alkyl sulphates are a versatile and economic class of surfactants with applications in such diverse areas as polymerisation and toothpaste. 

In piece, yarn, or garment dyeing a two-stage method consisting of application of the Naphthol first followed by coupling with a Fast Salt is preferred. The Fast Salts are diazotized bases stabilized by formation of double salts with compounds such as zinc chloride, aluminium chloride, alkyl sulphates, benzene sulphonic acid, and 1 5 naphthalene disulphonic acid. 

Despite its potential application to charged surfactant analysis, there have been relatively few publications of ion chromatography applications. Dionex in their applications literature demonstrate several possible separations including alkyl sulphates the separation of sodium isethion-ate from its alkyl isethionate ester on a Vydac 302 IC column with methanol 20mM phthalic acid water (3 5 12, 2.5) and conductivity detection is described in [49]. 

Monoester sulphosuccinates use a wider variety of alcohols than diesters and tend to use longer carbon chain alcohols to obtain the required HLB value from a single alkyl group. A typical product for cleansing applications would use a C12-14 alcohol derived from coconut or palm kernel oil. These materials are easily available due to their use as raw materials for sulphation (see later). Effective sulphosuccinates can also be prepared from petrochemical alcohols but these seem to be less popular. Ethoxylated alcohols (typically 3 mol of EO) are also used and can provide additional benefits in personal care applications. In some cases, alkanolamides or ethoxylated alkanolamides are used as the alcohol, such as ethoxylated cocomonoethanolamide, but they are relatively uncommon, since they are difficult to manufacture and are prone to colouration. 

This class of surfactants has possibly the widest range of use of any anionic surfactant. It is found in almost every product where foaming is desirable, in industrial, household and personal care applications. Alkyl ether sulphates are described in terms of their parent alcohol and the degree of ethoxylation. Thus, sodium laureth-2 is the sodium salt of a sulphated (predominantly) C12 alcohol, with an average of 2 mol of ethylene oxide added. Often, the alcohol is assumed to be the typical C12-14 and the surfactant simply called a 2-or 3-mol ether sulphate. 

Applications. Alkyl ether sulphates are almost ubiquitous in cleaning products but are rarely found as the primary surfactant as they bring only some detergency but mainly contribute to foaming and viscosity building. 

They are a versatile surfactant type, with some properties analogous to those of ether sulphates. Unlike sulphate (which is a sulphuric acid mono alkyl ester), phosphate can form di- and triester, giving a wider range of structures and, with them, the ability to tailor the product to a greater number of application areas. 

Applications. As medium foaming/hydrotropic surfactants, PEs can be used in detergent cleansing applications with the short chain alkyl esters being effective hydrotropes for nonionic surfactants. Application of PEs in detergents is relatively limited, due to their cost compared to a sulphate/sulphonate, or non-ionic but long chain diesters can be used as effective de-foamers in anionic systems. 

In the 1930s a number of long-all l-chain sulphonates (anionic chemicals), alkyl aryl sulphonates, and sulphates replaced the soaps. Unlike the sulphonates, sulphates are susceptible to hydrolysis, so that pH control is important for sulphate solutions. In dehydration applications the sulphonates exhibit fair to good wetting and water drop performance, some ability to brighten oil, and very little tendency to overtreat, particularly in high-gravity emulsions [1, 2],... 

Alternatively, a method is described for alkyl ether sulphates, which would also be applicable to alcohol ethoxylates, in which the equilibrium head-space is analysed on a 3 m x 1.8 mm i.d. column of 0.8% THEED/ Carbopack C (80-100 mesh) [14]. A detection limit with FID of 0.1 ppm is claimed. For improved quantitation, both methods can be adapted to a method of standard additions. 

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