Existence of Two Soil Species in Detergency Investigations

Abstract

ALTHOUGH a considerable amount of research has been devoted to the examination of detergency, little work has been done on rates of soil removal. Durham¹ has commented on the need for kinetic studies in detergency research. We have examined the kinetics of detergency in a model circulation cleaning system. In this model system a detergent solution (0.03 M sodium hydroxide) is pumped from a 50-gallon tank through a short length of 1½-in. diam. pipe in a closed system. Test strips of stainless steel 3.6 cm × 32 cm are soiled on one side with a very thin, layer of pure synthetic tristearin labelled with carbon-14. The test strip is placed in the pipe, the detergent solution is pumped past the strip for a fixed time under closely controlled conditions after which the pipe is drained and the strip is removed. The amount of tristearin taken off the strip is found by measuring the radioactivity before and after each treatment. By means of repeated cleaning treatments on one strip, a cleaning curve is obtained.