Ethoxylated anionic surfactants, effect

Effect of Ethoxylated Anionic Surfactants. Model system results for a series of sodium lauryl polyoxyethylene sulfates and sulfonates are presented in Table III. Surprisingly, the PLMA MW does not vary with the degree of ethoxylation However, the sulfonate results have larger M Ws than the sulfate results. 

In the 1990s, the thmst of surfactant flooding work has been to develop surfactants which provide low interfacial tensions in saline media, particularly seawater require less cosurfactant are effective at low concentrations and exhibit lower adsorption on rock. Nonionic surfactants such as alcohol ethoxylates, alkylphenol ethoxylates (215) and propoxylates (216), and alcohol propoxylates (216) have been evaluated for this appHcation. More recently, anionic surfactants have been used (216—230). 

It has been claimed that complexes of P-cyclodextrin with anionic surfactants, notably higher fatty alcohol ethoxylates, improve scouring efficiency on cotton and wool in laboratory-scale processing [34]. Residual surfactants carried over from preparation can have undesirable effects in subsequent processing. When cyclodextrins complex with surfactants, their surface activity is reduced. Hence cyclodextrins are potentially useful for the removal of residual amounts of surfactants from substrates [35]. The use of a- and P-cyclodextrins has been studied in this context with one cationic, one anionic and four... 

Fig. 10 Effect of surfactant concentration on the optimum formulation (minimum tension position) for anionic mixtures (/e/t), pure anionic surfactant center) and ethoxylated nonionic mixtures (right)...

A widely available anionic surfactant is sodium lauryl sulfate. This surfactant is fairly irritating to skin. Ethoxylation of this surfactant lowers its irritation potential but it also lowers its lather. The optimal mildness and lather is obtained with a degree of ethoxylation of 2 or 3. This surfactant is widely used with 2 moles of ethoxylation (laureth 2-sulfate) and is available as 28% active or 70% active. In some cases it is also used with 3 moles of ethoxylation (laureth 3-sulfate). The loss of lather due to ethoxylation is generally compensated for by using foam boosters such as lauramide diethanolamide, cocamide diethanolamide, and amine oxides. Alfa olefin sulfonate is another cost-effective surfactant emerging as a popular surfactant for liquid soap formulations [7],... 

Figure 6a. The effect of anionic surfactants used in latex synthesis on the viscosity of 2% solution of HEUR 270. Key A, ammonium salt of nonylphenol ethoxylate average 20 oxyethylene units) sulfate O, ammonium salt of nonylphenol ethoxylate average 9 oxyethylene units) sulfate.

Figure 1.1 presents the consumption of the major surfactants in the world market in 1996. Along with soap, linear alkylbenzene sulphonates (LAS) remain the most bulky and cost-effective anionic surfactants. LAS will continue to be the workhorse of the detergents industry on a global basis. However, the LAS share decreases gradually their recess is occupied by alcohol-derived surfactants, first of all alcohol sulphates (AS), alcohol ethoxylates (AE) and alcohol ether sulphates (AES). In West Europe alkylphenol ethoxylates (APE) have been removed over the last two decades from a large number of household applications in view of... 

The effect of temperature and surfactants on the viscosity of coal-water mixtures is shown in [281]. It has been shown that the volume content of coal in suspension can be increased while preserving its flowability at a certain surfactant content. Stable and pseudo-plastic suspensions were obtained both with anionic surfactants containing electrolyte, and with ethoxylated alkylphenols with a high content of oxyethylene groups. But the rate of reduction of the apparent viscosity begins to decrease with increasing temperature which seems to be connected with the change of the surfactant structure in solution and adsorption layers. 

Figure 6 8 Effect on initial droplet size of concentrations of (a) the anionic surfactants sodium dodecylben-zene sulfonate (DoBS), sulfated hexadecyl alcohol (C16-S) and sulfated hexadecyl/octadecyl alcohol ethoxylate (2 EO) (C16/C18-E02-S) and (b) the nonionic surfactants dode-cyl/tridecyl alcohol ethoxylate (15 EO) (C12/C13-E015), nonylphenol ethoxylate (20 EO) (NP-EO20) and linseed oil fatty acid monoethanolamide ethoxylate (13 EO) (LA 13). (From G. Ostberg et al.. Colloids Surf. A, 94, 161 (1995)...

As in the example of the detergent formulation used to obtain the foam profiles shown in Figure 8.4, early attempts to develop praetieal washing powder formulations suitable for foam-intolerant, front-loading drum-type laundry washing machines utilized the antifoam effect of calcium soaps in mixed anionic and ethoxylated alcohol surfactant systems. The approach appears to have been entirely empirical. The foam behavior of ternary mixtures of anionie surfaetants, sueh as sodium alkylbenzene sulfonates, various ethoxylated alcohols, and soaps, was optimized for low foamabil-ity in relevant machines by systematie trial. Obviously, polyvalent metal ion (especially calcium) activity as determined by temperature, water hardness, and builder type and concentration represented an additional variable. Wash temperature and pH... 

As we have seen, the presence of ethoxylated non-ionic surface-active compounds can enhance the susceptibility of the foam of solutions of anionic surfactants to antifoam. This appears to be a general phenomenon that is also manifest with PDMS-hydrophobed silica antifoams in wash cycles with drum-type, front-loading, textile washing machines. This well-known effect is exemplified in Figure 8.13 where the addition of ethoxylated alcohols is seen to diminish the foam profile of solntions of sodinm alkylbenzene snlfonate (LAS) in the presence of PDMS-hydrophobed silica antifoam. Sawicki [7] has shown that the effect of these ethoxylated componnds does not concern either the precipitation of cloud phase drops (see Section 4.6.3.2) or marked changes in dynamic or equilibrium air-water solution snrface tensions. One possible explanation could concern a putative inhibiting effect of ethoxylated compounds upon the rate of PDMS-hydrophobed silica antifoam deactivation. However, this would afford no explanation for the effect of those componnds on the antifoam action of hydrophobic precipitates where no oil is present (see Section 8.2.2). 

Sawicki [7] notes that these ethoxylated componnds appear to coadsorb with anionic surfactants at the air-water surface and specnlates that this conld prodnce a reduction in the stability of the relevant oil-water-air psendoemnlsion films. There have, however, apparently been no relevant experimental stndies of this possibility. Moreover, since the antifoam enhancement effect is also manifest with particnlate precipitates in the absence of oil, the generality of both phenomenon and explanation would have to imply an equivalent effect of the ethoxylated componnds on the stability of particle-water-air films. Clearly we have an issne that demands attention ... 

Mixtures of surfactants exhibit different levels of synergism depending on the charge and molecular structure of the individual surfactant components [7]. When ionic and nonionic surfactants are mixed, the properties of the two surfactants are maintained. In mixtures of cationic and nonionic surfactants, in general, no synergistic or antagonistic effect is observed. In mixtures of anionic surfactants and some nonionic surfactants such as alcohol ethoxylates, however, some synergistic effect is observed. In contrast to mixtures of ionic and nonionic surfactants, mixtures of anionic and cationic surfactants have properties that are drastically different from their ionic surfactant components. These differences will be discussed in detail below. 

To develop new products for the prewash market, understanding how surfactants that are not normally found in detergent formulations perform as a prewash product is essential. In the past, the majority of the surfactants in these products were ethoxylated alcohols and anionic surfactants. These products are effective and economical. 

Features Effective for nonlonic and anionic surfactants, and glycol ethers into mod. alkaline formulations cost effective for use in formulations that require extremely high levels (>15%) of sodium xylene sulfonate alkyl phenol ethoxylate free Properties Off-wh. cl. liq. sp.gr. 1.04 dens. 8.67 Ib/gal vise. 130 cP pH (1% aq.) 7.0 45% act. 

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