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Krafft point of cationic and zwitterionic surfactants in aqueous solutions

 

 

 

Key words: 

Krafft point, cationic surfactants, zwitterionic surfactants. 

Summary Surface active agents (surfactants) are chemical structures consisting of two main parts:  a polar head group and a nonpolar hydrophobic chain frequently called as the surfactant’s tail. One of the important parameters characterizing a practical suitability of surfactants in aqueous solutions is the Krafft point. This is the temperature (or more precisely, the narrow range of temperatures) above which the solubility of a given surfactant in water increases rapidly. The knowledge of the Krafft temperature of any surfactant is required to design a composition of new domestic detergents, shampoos, and cosmetic products of high quality in which a given surfactant can be used an active ingredient. In this work we report results of our investigation on the relationship between the Krafft temperature of cationic and zwitterionic surfactants in aqueous solutions and their chemical structure. We tested empirical values of the Krafft point available in literature for aqueous solutions of 50 cationic and zwitterionic surfactants and correlated them to the surfactant chemical structure. We propose a novel set of 24 group contributions for calculation the Krafft temperature of these surfactants in aqueous solutions. Using them, the Krafft temperature values in aqueous solutions for 36 cationic and 14 zwitterionic surfactants were calculated and the estimated values obtained in this way were compared with experimental values. We have demonstrated that the newly developed set of numerical values structural group contributions of the surfactants allows correct estimation of the Krafft temperature value for the tested set of data with the maximum error 4.4oC and the mean square error 2.5oC for various types of ionic surfactants in aqueous solutions. 

Prof. dr hab. inż. Ryszard ZIELIŃSKI

Poznan University of Economics and Business Faculty of Commodity Science Department of Technology and Instrumental Analysis Aleja Niepodległości 10, 61-875 Poznań, Poland tel.: (+48) 61-8569056 e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it. 

 

 

 

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