Anionic surfactants alkyl ether sulfate

Other Anionic Surfactants Alkyl Ether Sulfates... 

High-performance liquid chromatography is performed using a Hewlett-Packard 1090 chromatograph equipped with a ternary-solvent delivery system, an autoinjector with a 0 -20- u.L injection loop, an oven compartment, and a diode-array UV detector. An ELS detector (Alltech Associates, Deerfield, IL) is connected in series to the UV detector. Hexane, 2-propanol, and water were used for the analysis of nonionic surfactants. Water and tetrahydrofuran (THF) are used for the analysis of anionic surfactants. No preliminary sample preparation is used other than dilution. The nonionic surfactants are diluted 1 40 (v/v) with hexane. The anionic surfactants (alkyl ether sulfates and synthetic and petroleum sulfonates) are diluted 1 20 (v/v) with water-THF (50 50). The calcium sulfonate surfactants were diluted 1 20 (v/v) with a THF-38% hydrochloric acid solution of pH 1. Hydrochloric add is required to prevent salt precipitation by converting any excess water-insoluble caldum carbonate into water-soluble calcium chloride. All diluted samples are... 

Alkyl ether sulfates are/after alkyl benzene sulfonates(LAS),the group of technically important anionic surfactants with the largest production voluJne and product value. They have in comparison with other anionic surfactants special properties which are based on the particular structure of the molecule. These are expressed,for example,in the general adsorption properties at different interfaces, and in the Krafft-Point. Alkyl ether sulfates may be used under conditions, at which the utilization of other surfactant classes is very limited. They possess particularly favorable interfacial and application properties in mixtures with other surfactants. The paper gives a review of all important mechanisms of action and properties of interest for application. 

Alkyl ether sulfates with chain lengths ranging from to Cw are quantitatively the most important products currently based on fatty alcohols. It is estimated, that about 20 % of all surfactant alcohols -about 40 % of all fatty alcohols in the coconut range (C,2 Ci,) - are used in the form of alkyl ether suirateg ( ). Alkyl ether sulfates are the most important group of anionic surfactants after linear alkyl-benzenesulfonate (LAS) (2). 

In 1980, the total consumption of alkyl ether sulfates in Western Europe equaled that of all other anionic surfactants with the exception of alkyIbenzene-sulfonates (Fig. 1). Since alkyl ether sulfates are the most expensive group of anionic surfactants, which are produced in larger quantities, their importance on a... 

An especially effective reduction of the Krafft Point results from the insertion of ether groups into the molecule of the anionic surfactant. In table I this is examplified with Na dodecyl sulfate and Na-tetra-decyl sulfate in comparison to various n-alkyl ether sulfates of the same chain length (10). As a measure of the Krafft Point, a temperature is deTined at which a 1 7o solution dissolves clearly. By the incorporation of oxyalkylene groups into the molecule, the Krafft -Point and the melting point are greatly depressed. This depression is especially effective if there is branching in the oxyalkylene groups. 

Washing and Cleaning Action. The properties of alkyl ether sulfates, due to the good solubility and the special hydrophilic/hydrophobic properties of the molecule, are of particular practical interest. From the investigations described in sections 2 and 3, it can be concluded that, in addition to the decrease in the Krafft Point, favorable properties for practical applications can be expected as a result of the inclusion of the oxyethylene groups into the hydrophobic part of the molecule. As is true for other anionic surfactants, the electrical double layer will be compressed by the addition of multivalent cations. By this means, the adsorption at the interface is increased, the surface activity is raised, and, furthermore, the critical micelle concentration decreased. In the case of the alkyl ether sulfates, however these effects can be obtained without encountering undesirable salting out effects. 

In most products,alkyl ether sulfates are used in form of mixtures with other surfactants. Alkyl benzene sulfonate (LAS) is the most important anionic surfactant used in combination with alkyl ether sulfates. 

Anionic surfactant Sodium dodecyl sulfate (SDS, C] 2 25 3 supplied by Nihon Surfactant Industries Co., Ltd Tokyo, Japan. It was extracted with ether and recrystallized from ethanol. The purity was ascertained by surface tension measurement. Nonionic surfactant Alkyl poly(oxyethylene) ether (CjjPOEjj, CmH2nhPlO(CH2CH20)2oH, m=12, 14, 16, and 18 Ci6H330(CH2CH20) H, n=10, 20, 30, and 40) were supplied by Nihon Surfactant Industries Co., Ltd. These have a narrow molecular weight distribution. 

Alkyl ether sulfates (AES) are anionic surfactants obtained by ethoxy-lation and subsequent salfation of alcohols derived from feedstock or synthetic alcohol. AES, also known as alcohol ether sulfates, have low sensitivity to water hardness (Fig. 5.3), high solubility, and good storage stability at low temperature [4, 11]. 

Anionic alkyl ether sulfate surfactants are produced by sulfating nonionic alcohol polyalkyloxylates such as the ethoxylated surfactants discussed earlier. The sul-fated products generally contain variable amounts of unconverted alcohols and inorganic salts as reaction by-products. Determination of the ratio of anionic to nonionic components in surfactant mixtures is desired for quality control and performance evaluation. Separation of the ionic sulfate and nonionic alcohol components is achieved by reversed-phase chromatography. The separation of four alkyl ether sulfate surfactants is shown in Table 3. 

Anionic surfactant (typically alkylbenzene sulfonate, alkyl ether sulfate) 0-40... 

High-concentration flowable anionic surfactant mixtures containing alkyl ether sulfates and alkyl sulfates... 

Light-duty or gel dishwashing compositions containing an alkyl ether sulfate-based anionic surfactant, polyhydroxy fatty acid amide nonionic surfactant, suds boosters/stabilizers, aqueous liquid carrier, pH control agent, and acrylic copolymer thickener are disclosed in U.S. Patent 6,274,539. Viscosity as determined... 

Surfactants anionics sodium lauryl ether sulfate (SLES) and sodium lauryl sulfate (SLS) amphoteric cocamidopropyl betaine (CAPB) nonionic alkyl polyglucoside (APG). 

Sodium Alkyl Ether Sulfate Anionic Surfactant 0-10... 

This section briefly describes the anionic and nonionic surfactants commonly used in commercial HDLD formulations. Cationic surfactants, although used on a large scale, are found predominantly in rinse-added fabric softener products. LAS, alcohol ethoxylates, and alkyl ether sulfates are three of the most widely used surfactants in liquid laundry detergents [44], Recently, various external considerations, such as environmental pressures, have prompted manufacturers to change their surfactant mix to include newer natural-based surfactants [45-47], including alkyl polyglucosides (Henkel) [48],... 

Other soils have not been studied so extensively however, Robbins et al. [29] have shown that Cn alkyl sulfates or alkyl ether sulfates, the traditional shampoo surfactants, do not remove cationic surfactants from hair effectively under certain conditions. However, shorter chain-length anionics such as deceth-2 sulfate is more effective for removing cationics. In addition, alkyl ether sulfates are more effective for removing fatty acid soils in the presence of water hardness than alkyl sulfates [29]. 

More important for a toxicological evaluation is the fact that amphoterics are usually combined with anionic surfactants, i.e. alkyl or alkyl ether sulfates. Such blends are assessed to be very mild to skin and mucous membranes (60, 61). 

A characteristic example in the field of cosmetics is the separation and determination of anionic surfactants in shampoos. The only required sample preparation step is the dilution of the product to be analyzed in de-ionized water and subsequent membrane filtration (0.45 pm) prior to injection. Figure 9-129 illustrates the gradient elution of anionic surfactants in a commercial shampoo with simultaneous non-suppressed conductivity and UV detection. While the peak pattern in the UV trace indicates the presence of alkylbenzene sulfonate (ABS) (see also Fig. 6-42 in Section 6.5), the characteristic peak profile for alkyl-ether sulfates (see Fig. 6-41 in Section 6.5) is evident in the conductivity trace after visual subtraction of the ABS signal. Therefore, ion chromatography provides a way to unequivocally identify surfactant raw materials in finished cosmetic products without time-consuming sample preparation. 

Applications. Alkyl ether sulfates constitute (with LAS and alkyl sulfates) one of the most important group among anionic surfactants. They are used in a broad spectrum of domestic applications such as household cleaners (e.g., carpet cleaners), dishwashing liquids, and fabric care (powders and liquids). 

In the above cleaning areas, alkyl ether sulfates, which are rather expensive raw materials, are generally combined with other nonionic or anionic surfactants, thereby their contribution to bringing the foaming, degreasing, or viscous properties of products to their expected levels. 

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