engleski

Differential potentiometric titration of cationic and ethoxylated nonionic surfactants mixtures

A sensitive potentiometric surfactant sensor based on 1, 3-didecyl-2-methyl-imidazolium cation and a tetraphenylborate antagonist ion has been used as the end-point detector in ion-pair surfactant potentiometric titrations using sodium tetraphenylborate as titrant. Several analytical and technical grade cationic (CS) and ethoxylated nonionic surfactants (EONS), single and the mixtures of both were potentiometrically titrated. Barium ions forms pseudocationic complex with ethoxylated nonionic surfactant that can be titrated simultaneously with cationic surfactant (CS) using the same anionic titrant. Due to differences in hydrophobicity of both, nonionic and cationic surfactant investigated, ion associates formed during the titration revealed different stability constants resulting in two, more or less pronounced, analytically usable inflexions in the titration curve. The sensor showed satisfactory analytical performances within a pH range of two through eleven, and exhibited satisfactory selectivity for both, CS and EONS investigated. The sensor was tested on several formulated powdered and liquid detergent products of various composition complexity too.

surfactant sensor; cationic surfactant; ethoxylated nonionic surfactant; potentiometric titration

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