Abstract:

The effects of added 1-1 type sodium salts on the aqueous solutions of five nonionic surfactants (i.e. Triton X-100, Triton X-114, Triton X-305, Igepal CO-720 and Igepal CO-890) have been investigated systematically. The effectiveness of monovalent anions in decreasing cloud point of nonionic surfactant solutions varies in the order IO3- >OH- >F- >CH3COO- >BrO3- >Cl- >Br- > ClO3-≥NO3-, while in increasing cloud point of nonionic surfactant solutions varies in the order CNS- >ClO4- >I-. The experimental data indicate that the efficiency in cloud point decreasing or increasing depends primarily on the electrolyte and not the nonionic surfactant. As the cloud point of Triton X-305 and Igepal CO-890 both exceed 100℃, the routine measurement is useless. Two procedures have been proposed to solve the problem by the addition of electrolytes which decreases the cloud point of nonionic surfactant. This leads to the cloud point of 112℃ and 116℃ for Triton X-305 and Igepal CO-890 respectively.

Key words: Cloud point, Nonionic surfactant, Electrolyte