Ethylene oxide distribution

Recently, patented ethoxylation catalysts have become available that can significantly narrow the ethylene oxide distribution of the alcohol ethoxylates used to obtain alcohol ether sulfates. These products are termed peaked alcohol ether sulfates whereas all others are termed conventional alcohol ether sulfates. Peaked alcohol ether sulfate solutions thicken more than those with a conventional ethylene oxide distribution [78]. Peaked alcohol ether sulfate solutions also exhibit behaviors different from those of conventional sulfates [79]. Smith [78] studied the viscosities of 15% sodium dodecyl ether sulfate solutions of both families with NaCl content between 2% and 10% at 25°C using a Brookfield model DVII viscometer at a shear rate of 2 s 1. The results are shown in Fig. 5 where the very different viscosities achieved are clearly observed. 

Generally ether carboxylates are not suitable for a syndet soap because they are waxy due to the ethylene oxide distribution. The solid ether carboxylates with a long alkyl chain and a low degree of ethoxylation have a bad foam. By use of nonethoxylated ether carboxylates, e.g., a carboxymethylated fatty acid monoethanolamide with the structure... 

As a test, surfactant slug flow experiments were performed in clayey sandpacks with and without the injection of a desorbent behind the micellar slug. Results show that a substantial decrease in surfactant retention is obtained in calcic environment by such an additive. Likewise, the ethoxylated cosurfactant in the micellar slug can be remobilized simultaneously with sulfonatewithout any change in its ethylene oxide distribution. The application of the RST to sulfonate/ ethoxylated alkylphenol mixtures explains semi-quantitatively the relationship between their properties and composition. 

The sulfonate content was determined either by the well-known technique of two-phase titration with hyamine or by liquid chromatography (HPCL). Nonionic surfactants were analyzed by HPLC (16) in the reverse or normal phase mode depending on whether the aim was to determine their content in effluents or to compare their ethylene oxide distribution. 

Likewise, in order to evaluate nonionics transport, ethylene-oxide distribution in the cosurfactant (Genapol) was determined by HPLC at two stages of production in test 7 (1) before breakthrough of the desorbent, i.e. in the presence of sulfonate in the effluent and (2) after its breakthrough when the three additives coexist in solution in the form of mixed micelles. 

Figure 7 shows the quasi identity of the ethylene-oxide distributions of the Genapol samples, analyzed at the outlet of the porous medium. For nonylphenols with 14 and 30 EO, we also checked that the distribution of these nonionic agents (injected in a concentration of 5 g/1) was not appreciably changed after transit via the adsorbent porous medium. Under these conditions, the mixed micelles formed... 

Figure 7. Ethylene oxide distribution of cosurfactant produced before (A) and after (B) desorbent breakthrough. (Reproduced with permission from ref. 16. Copyright 1987 Deutsche Wissenschaftliche Gesellschaft.)...

In the same way, after transit through a porous medium, non appreciable change was found in the ethylene oxide distribution of nonionic surfactants used as a cosurfactant or desorbent. 

Surfactants are separated according to adsorption or partitioning differences with a polar stationary phase in NPLC. This retention of the polar surfactant moiety allows for the separation of the ethylene oxide distribution. Of all the NPLC packings that have been utilized to separate nonionic surfactants, the aminopropyl-bonded stationary phases have been shown to give the best resolution (Jandera et al., 1990). The separation of the octylphenol ethoxylate oligomers on an amino silica column is shown in Fig. 18.4. Similar to the capabilities of CE for ionic surfactants, the ethylene oxide distribution can be quantitatively determined by NPLC if identity and response factors for each oligomer are known. 

Since NPLC can separate the ethylene oxide distribution and RPLC separates according to the alkyl distribution, the combination of these two techniques into a 2LDC system was shown to resolve both distributions in one analysis (Murphy et al., 1998b). This is discussed in the NPLC coupled to RPLC section. 

Ethoxylated alkyl amines in pesticide formulations were separated using two different columns a cyano-modified silica column to determine the alkyl distribution and an amino-modified column to determine the ethylene oxide distribution [88]. The detection, specific for ethoxylated amine, was performed with a post-column ion-pair extraction system and fluorescence detection. 

Absorbed ethylene oxide is rapidly distributed throughout the body. In mice exposed by inhalation to radiolabeled ethylene oxide, distribution was immediate, with the highest concentrations of ethylene oxide or its metabolites in the lungs, liver, and kidneys. After 4 h, levels in the liver and kidney had decreased and were comparable to those detected in the lungs, testes, spleen, and brain. 

Primary alcohol ethoxylates are an important class of detergent feedstock for anionic active manufacture. They are made by the addition of ethylene oxide to a primary alcohol in the presence of an alkaline catalyst. The addition of the second ethylene oxide molecule to the alcohol is kinetically favoured in comparison with the addition of the first ethylene oxide, hence the product of ethoxylation contains a distribution of ethylene oxide chain lengths attached to the alcohol along with the starting alcohol itself. Consequently the physical, detergency and biodegradation characteristics are affected not only by the carbon chain length distribution as is the case for primary alcohols, but also by the ethylene oxide distribution which in turn can be supplier dependent. 

FIG. 3 (A) Ethylene oxide distribution (via supercritical liquid chromatography) of Ci4 methyl ester ethoxylate obtained with conventional (NaOH) catalyst. (B) Ethylene oxide distribution (via supercritical liquid chromatography) of C14 methyl ester ethoxylate obtained with Ca/Al-alkoxide catalyst. (From Ref. 27.) (C) Ethylene oxide distribution (via supercritical liquid chromatography) of C14 alcohol ethoxylate obtained with conventional (NaOH) catalyst. (D) Ethylene oxide distribution (via supercritical liquid chromatography) of C14 alcohol ethoxylate obtained with Ca/Al-alkoxide catalyst. (From Ref. 27.)... 

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