Sulphates ethoxylated

The salts of monoesters of sulphuric acid (mainly known as alkyl sulphates, alcohol sulphates or sulphated higher alcohols and ether sulphates or sulphated ethoxylated alcohols) have been proceeded for tens of years through the competition with alkylbenzenesulphonates and other anionic and nonionic surfactants with respect to the consumer s merits and cost performance. Among other surfactants, the today s world consumption share of alcohol sulphates and ether sulphates is ca. 25 % in household and laundry aids and ca. 20 % in personal care products [81]. The formers are mostly based on sulphates of petrochemical origin whereas the least are more oriented to sulphates from oleochemicals. 

AlkyIbenzene sulphonation Primary alcohol sulphation Ethoxylated alcohol sulphation Alpha-olefin sulphonation (AOS)... 

Alkyl sulphates Alkylether sulphates Sulphated alkanolamides (also sulphated ethoxylated derivatives) Monoglyceride sulphates Sulphated alkylphenol ethoxylates (typically R = C9H19-, n = 3 or more)... 

Nowadays these compounds are usually blended with other surfactants, including nonionic types (section 9.6). In 1990 a typical low- or non-phosphate domestic detergent contained 7% linear alkylbenzenesulphonate and 6% nonionic fatty alcohol ethoxylate [16]. There is increasing use of the long-chain fatty alcohol poly(oxyethylene) sulphates previously described (e.g. 9.12) as a partial or complete replacement for linear alkylbenzenesulphonates [15] since they are made from renewable feedstocks such as tallow and palm oil [16]. 

Ethoxylated products can also feature as amphoteric surfactants an example is compound 9.55, an alkylamine poly(oxyethylene) sulphate. Of particular interest in textile processing are the trisubstituted alkylamino acids known as betaines N-alkylbetaines (9.56 R = C8-C16 alkyl) and acylaminoalkylbetaines (9.57 R = C10-C16 alkyl) are typical [30]. 

Anionic and cationic products generally tend to interact with each other, usually diminishing the surface-active properties of both and often resulting in precipitation of the complex formed. Amphoteric compounds can also be incompatible with anionics in acid solution but are generally compatible with cationics and nonionics. Interaction between anionic and cationic agents can sometimes be prevented by addition of a nonionic. In some cases, if an ethoxylated sulphate or phosphate is used as the anionic component a cationic compound produces no obvious precipitation, since the oxyethylene chain acts as dispersant for any complex that may be formed. 

Particularly effective is a mixture of anionic and nonionic agents, such as a mildly anionic sulphated alcohol ethoxylate with a nonionic alcohol ethoxylate. Ideally, foaming agents should ... 

Surfactants elimination via bile is faster in fed than in unfed fish [12,40], due to the higher secretion of bile into the digestive tract when fed. The fastest and slowest surfactants excreted were the linear alkylbenzene sulphonates (C12) and the alkyl sulphates (especially the C12-15) [12], respectively. Depuration of NP is quite rapid, 1.8-20 days in fathead minnows [32] and 4 days in the Atlantic salmon [41]. Within the same organism, differences in tissues were observed, with values of 20 h for adipose tissue and 18.5 h for muscle of rainbow trout [24]. The elimination rate of non-ionic surfactants is directly proportional to the ethoxylate unit number and inversely proportional to the alkyl chain length [33]. Average elimination rates (k2) of NPE02.8 and NP in clams were 1.8 and 1.4 per day, respectively [21], and decreasing k2 values from 0.19 to 0.001 per day were obtained from butylphenol to dodecylphenol in salmon [42]. 

Low cost Choose from the following most widely used ones soaps, linear alkylbenzene sulphonates (LABS), alcohol ethoxysulphates (AES), alcohol sulphates (AS), alkane or paraffin sulphonate (SAS), and alcohol ethoxylates (AE)... 

A reliable modification of the process for the estimation of methoxyl is that of the British Pharmacopoeia, 1932. The apparatus is shown in Fig. 80. A Pyrex flask (A) of about 100 c.cs. capacity, having a bulb (B) of about 70 c.cs. capacity blown on the side tube, contains the mixture of substance (about 0-2 gm.) and hydriodic acid (10 c.cs.). The side tube is connected through a smaller bulbed tube (0) to a set of bulbs (D, see Fig. 65), immersed in a water bath at 60° (95° for ethoxyl), containing red phosphorus suspended in a 2% aqueous solution of cadmium sulphate. To this is attached two absorption flasks (E), each containing about 20 c.cs. of the above alcoholic silver nitrate. To the flask (A) is... 

Dishwashing liquids Alkyl benzene sulphonates Alcohol ether sulphates Fatty alcohol ethoxylates Detergency/foaming... 

Hard surface cleaners Alkyl benzene sulphonates Alkanolamides Fatty alcohol ethoxylates Potassium oleic acid sulphonate Shorter chain alcohol ether sulphates Detergency high/low foaming... 

Polyglycol ethers Alkanolamides Alkyl ether sulphates Alkylbenzene sulphonates (amine salts) Alkylphenol ethoxylates Alkanolamides Alkylbenzene sulphonates (amine salts)... 

Resin emulsifiers Alkylphenol ether sulphates Fatty alcohol ether sulphates Fatty alcohol ethoxylates Emulsifiers... 

Coco imido dipropionate Fatty alcohol ethoxylates Alkyl sulphates Sodium dialkyl sulpho succinates Wetting agents... 

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. 

Chemistry and general properties. The chemistry of ether sulphates is very similar to that of alkyl sulphates. The backbone of the molecule is a fatty alcohol and often the same alcohols are used as feedstocks for alkyl sulphates, and alkyl ether sulphates and, with higher degrees of ethoxylation, as non-ionic surfactants. The ethoxylation process is more fully described in Chapter 5. 

The addition of an ethylene oxide chain to what is essentially an alkyl sulphate changes its properties in several important ways. Firstly the Kraft point is very significantly reduced. Low active solutions of ether sulphates are clear are fluid at temperatures close to 0°C, and the Kraft point reduces with increasing levels of ethoxylation. Secondly, the nature of foam changes, from the dense stable foam of an alkyl sulphate to a much more open foam structure. The tolerance of the surfactant to water hardness is also improved, with ether sulphates showing better foaming in the presence of moderate hardness. 

Raw materials. Feedstocks for ethoxylated alcohols are made from a large number of alcohols and practically every fatty alcohol used to make alkyl sulphates is also ethoxylated to make non-ionic surfactants, or feedstock for ether sulphates. 

Ether sulphates show a strong salt effect - that is an increase in viscosity on addition of salt (or other electrolyte). The response to electrolyte (the salt curve ) can be very different between ether sulphates, even from different suppliers of the same product. Generally, the more soluble the surfactant, the lower the salt response but higher degrees of ethoxylation reduce salt response, as does branching in the alcohol as shown in Figure 4.20. 

Raw materials. The alcohols used in PE manufacture are typically detergent alcohols but shorter chains may also be used. Ethoxylated alcohols, used as non-ionic surfactants in their own right, can also be phosphated to give a surfactant with properties intermediate between non-ionic and sulphated anionic. The provenance of the alcohols has already been covered in detail in the Section 4.2. 

Raw materials. The base materials for ether carboxylates are typically ethoxylated alcohols, although ethoxylated aromatics or alkanolamides may also be used but a wider range of alkyl chains and degrees of ethoxylation are used in ether carboxylates than in ether sulphates. Carbon chains from C4 to C20 and degrees of ethoxylation from 2 to 20 may be combined to give the required properties in the surfactant. 

Sources and properties of alcohol ethoxylates are covered in more detail under alkyl sulphates and alkyl ether sulphates. 

A key attribute of ether carboxylates is mildness which increases with EO number but this can also reduce detergency. Comparing sodium salts with a predominantly C12 alkyl chain, the 3-mol carboxylate would have a Zein score of 150, while the 13-mol one would score 80 (cf. laureth-2 sulphate at 270 and sodium lauryl sulphate at 490) [9]. The sodium salts show phase behaviour similar to ether sulphates but the position and scale of the viscosity minimum can be varied with C chain, degree of ethoxylation and, unlike ether sulphates, by the degree of neutralisation [9]. 

Ethoxylation is carried out in the same manner as for primary alcohols described earlier but, in general, only up to the 3-mol ethoxylate as a feedstock for some specialised ether sulphates. These products show some advantages in wetting and foaming applications compared to the straight alcohol sulphates. These twin tail surfactants require less co-surfactant to make microemulsions and emulsify 3-5 times more oil than sulphates made from linear hydrophobes. 

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