Precipitation of cetyl (hexadecyl) pyridineum chloride using mono and divalent oxyanions

Abstract

Experimental investigations have been carried out to observe the performance of precipitation behavior of potassium permanganate (KMnO 4) and potassium dichromate (K 2Cr 2O 7) in cetyl (hexadecyl) pyridineum chloride (CPC) solution. As in the case of Al 3+-dodecylbenzenesulfonate systems [P. Somasundaran, K.P. Anathapadmanabhan, M.S. Celik, Langmuir 4 (1988) 1061–1063], the precipitation is found to be caused by interaction of CPC micelles with oxyanions. The counter oxyanions have a strong tendency to bind themselves to the surface of cationic CPC micelles. This lowered the free oxyanion concentration in solution. Therefore, to start precipitation, higher oxyanion concentration is required for higher CPC concentration. The effects of temperature, concentrations of both counter ions and CPC on the precipitation have been studied in detail. It has been observed that at CPC to KMnO 4 concentration ratio of 1.0 (concentration of CPC and KMnO 4 is 400 ppm), the percentage precipitation of CPC is around 99.3 at 30 °C. The percent precipitation of CPC decreases to about 94% when temperature increases to 70 °C at the same condition. The extent of CPC precipitation increases at the same experimental condition when K 2Cr 2O 7 is used instead of KMnO 4.