Specific Salt and pH Effects on Foam Film of a pH Sensitive Surfactant

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• 作者：Cyril Micheau ; Pierre Bauduin ; Olivier Diat ; Sylvain Faure
• 刊名：Langmuir
• 出版年：2013
• 出版时间：July 9, 2013
• 年：2013
• 卷：29
• 期：27
• 页码：8472-8481
• 全文大小：461K
• 年卷期：v.29,no.27(July 9, 2013)
• ISSN：1520-5827

文摘

Steady state foams made of a pH sensitive surfactant, nonaoxyethylene oleylether carboxylic acid, with ion complexing properties was studied using small angle neutron scattering (SANS). The effect of pH variation and salt addition on the foam film thickness was investigated and discussed in terms of the influent parameters stabilizing the foam such as surface properties and electrostatic effects determined by tensiometry and zeta potential measurements. The decrease in the film thickness by adding mono (Na⁺) and divalent (Ca²⁺) salts is classically explained by screening of the double layer in foam films (transverse interactions). On the contrary, addition of acid or complexing ion (Nd³⁺) results in an increase in the film thickness and can be analyzed in terms of cohesive forces between surfactants at the liquid/gas interface (lateral interactions). pH and specific salt effects revealed that foams produced by nonaoxyethylene oleylether carboxylic acid are of interest in the potential use of this surfactant in ion separation process.