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- Blute, I, et al.
(författare)
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Solution behavior of a surfactant aldehyde – the oxidation product of an alcohol ethoxylate
- 1999
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Ingår i: Colloids and Surfaces A. - 0927-7757 .- 1873-4359. ; 150, s. 105-113
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Tidskriftsartikel (refereegranskat)abstract
- It has previously been shown that alcohol ethoxylates readily undergo autoxidation and that one of the major oxidation products is the surfactant aldehyde, i.e. an ethoxylate carrying a –CH2CHO group at the terminal end of the polyoxyethylene chain. In this work the cloud point, phase behavior and aggregation characteristics of the surfactant aldehyde produced by oxidation of C12H25(OCH2CH2)50H(CI2E5) are determined and compared with the values obtained with the parent surfactant. It was found that the physico-chemical behavior of the two species was very similar, which indicates that a considerable portion of the aldehyde group is in hydrated state, i.e. the surfactant aldehyde consists of a mixture of aldehyde in carbonyl form and the corresponding geminal diol. The cloud point of the surfactant aldehyde decreased rapidly with time, even when it was stored at low temperature. Also the parent surfactant and its homologue C12E6 exhibited a decrease in cloud point during storage. For instance, a 1% aqueous solution of C12E6 showed a cloud point decrease from 62 to 32°C after 4 months storage at 40°C. Such a change in solution behavior can have important practical implications.
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- Blute, I, et al.
(författare)
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Solution behaviour of a formate capped surfactant - the oxidation product of an alcohol ethoxylate.
- 1999
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Ingår i: Colloids and Surfaces A. - 0927-7757 .- 1873-4359. ; 160, s. 229-236
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Tidskriftsartikel (refereegranskat)abstract
- The solution behaviour has been investigated for an alcohol ethoxylate terminated with a formic acid ester. This compound has previously been reported to be an important degradation product in the auto-oxidation of alcohol ethoxylates. In this work we have investigated the solution behaviour of the formic acid ester surfactant C12H25(OCH2CH2)4OCHO (C12E4-OCHO). The pure formate was found to be sparsely soluble in water with no clear point at 0.1%. The critical micelle concentration was found to be 129 µM at 35°C, compared to 50 µM for the parent surfactant C12H25(OCH2CH2)5OH (C12E5). To mimic the behaviour of the oxidised surfactant, the formate was mixed in different ratios with C12E5 and the cloud point, surface tension and critical micelle concentration of these mixtures were studied. The gradual increase of formate was found to shift the cloud point and isotropic regions to lower temperatures. The cmc of the mixture was found to be lower than for the pure surfactant. The favourable interaction was analysed according to the non-ideal model by Rubingh and the interaction parameter, b, was determined to be -4, which is unusually large for a mixture of two nonionic surfactants. These results indicate that the reduction of cloud point observed during oxidation of nonionic surfactants can in part be attributed to the formation of formate esters.
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