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
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.