CMC prediction for ionic surfactants in pure water and aqueous salt solutions based solely on tabulated molecular parameters

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:501

Article

Karakashev, Stoyan I.¹  Smoukov, Stoyan K.² 

[1] Univ Sofia, Dept Phys Chem, Sofia 1164, Bulgaria

[2] Univ Cambridge, Dept Mat Sci & Met, 27 Charles Babbage Rd, Cambridge CB3 0FS, England

关键词: Critical micelle concentration (CMC);    Adsorption capacity;    Adsorption energy;    Equilibrium adsorption constant;    Ion-specific effects;   

DOI  :  10.1016/j.jcis.2017.04.046

来源: Elsevier

【 摘 要 】

The critical micelle concentration (CMC) of various surfactants is difficult to predict accurately, yet often necessary to do in both industry and science. Hence, quantum-chemical software packages for precise calculation of CMC were developed, but they are expensive and time consuming. We show here an easy method for calculating CMC with a reasonable accuracy. Firstly, CMC0 (intrinsic CMC, absent added salt) was coupled with quantitative structure - property relationship (QSPR) with defined by us parameter CMC predictor f(1). It can be easily calculated from a number of tabulated molecular parameters - the adsorption energy of surfactant's head, the adsorption energy of its methylene groups, its number of carbon atoms, the specific adsorption energy of its counter-ions, their valency and bare radius. We applied this method to determine CMC0 to a test set of 11 ionic surfactants, yielding 7.5% accuracy. Furthermore, we calculated CMC in the presence of added salts using the advanced version of Corrin-Harkins equation, which accounts for both the intrinsic and the added counter-ions. Our salt-saturation multiplier, accounts for both the type and concentration of the added counter-ions. We applied our theory to a test set containing 11 anionic/cationic surfactant + salt systems, achieving 8% accuracy. (C) 2017 Elsevier Inc. All rights reserved.

【 授权许可】

Free