Stability of hydrophobic sols in the presence of non-ionic surface-active agents. Part 1.—Electrokinetic and adsorption measurements on silver iodide sols and suspensions

Abstract

The electrophoretic mobility of sols and suspensions of silver iodide has been investigated in the presence of a series of homogeneous non-ionic detergents of the alkyl polyoxyethylene glycol monocther type. Just before the critical micelle concentration of the non-ionic detergent was reached a pronounced decrease in the mobility of the particles was observed. Adsorption isotherms of the alkyl hexaoxyethylene glycol monoethers on silver iodide powder also showed a pronounced increase in adsorption in the same concentration region. The changes were consistent with the formation of a multilayer of non-ionic detergent on the surface which caused a displacement of the electro-kinetic plane of shear away from the surface. Adsorption of non-ionic detergent at the silver iodide/solution interface inhibited the adsorption of lanthanum, barium and sulphate ions.