## ملخص

The effect of salinity and degree of ethoxylation on the cloud point, T_{cp}, in C_{13}EO_{x} (x = 10–19) micelles was investigated in distilled water and in the salinity range S = 1.96–196 g L^{−1}. At a fixed x value, the rate dT_{cp}/dS was given by dT_{cp}/dS = α_{b} + β_{b}S with α_{b} < 0 and β_{b} > 0. This trend suggests that dT_{cp}/dS is the result of two opposing effects, an entirely (negative) surfactant-dependent effect (α_{b}) and a combined (positive) surfactant-solvent (β_{b}S)-dependent effect. In addition, the rate dT_{cp}/dS was found to become increasingly less negative with increasing salinity (dT_{cp}/dS) < 0), suggesting an overwhelming contribution of the α_{b} effect as compared to the β_{b}S effect. On the other hand, at fixed S, the rate was given by dT_{cp}/dx = α_{x} + β_{x}x with α_{x} > 0 and β_{x} < 0. This trend also suggests the existence of two opposing effects, a strictly (positive) solvent-dependent effect (α_{x}) and a concomitant solvent (β_{x})-surfactant (x)-dependent effect. Contrary to dT_{cp/}dS, the rate dT_{cp}/dx was found to become increasingly less positive with increasing x values (dT_{cp}/dx > 0), suggesting that α_{x} is the dominant factor in the surfactants’ susceptibility to be salted in. Both constants α_{b} and α_{x} were attributed to a dual temperature-salinity effect on the structure of water molecules not involved in surfactant's hydration. On the other hand, β_{b} and β_{x} were associated with the change in the structure of water due to the dehydration of surfactants’ oxyethylene moieties with increasing temperature.

اللغة الأصلية | English |
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دورية | Journal of Surfactants and Detergents |

المعرِّفات الرقمية للأشياء | |

حالة النشر | Accepted/In press - يناير 1 2018 |

## ASJC Scopus subject areas

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## بصمة

أدرس بدقة موضوعات البحث “Clouding Behavior of C_{13}EO

_{x}(x = 10–19) Micelles in a Wide Range of Salinity and Hardness: Concomitant Effects of Salinity and Degree of Ethoxylation'. فهما يشكلان معًا بصمة فريدة.