THE DIRECT STUDY OF OILY SOIL REMOVAL FROM SOLID SUBSTRATES IN DETERGENCY

A novel experimental technique for investigating the removal of small oil droplets from solid substrates by hydrodynamic forces is described . The droplet, in an aqueous environment, is subject to a controlled h ydrodynamic flow of axially symmetric geometry, and the technique allo ws the removal process to be studied as a function of such factors as the contact angle, the interfacial tension, the droplet size and the s ubstrate type, in both the absence and presence of surfactants. Contro l can thus be exerted over a number of physicochemical factors of prim ary importance in the detergency process; such control is absent in th e traditional Tergotometer approach. An experimental study of both the partial and total removal processes is thus made possible. Some preli minary results are presented.