Real Time Monitoring of the Detergency Process by Using a Quartz Crystal Microbalance

Abstract

A quartz crystal microbalance (QCM) technique has been employed to examine the detergency process involved when solid organic soils are removed from hard surfaces by surfactants. Experiments have been designed to focus on real time monitoring of the physicochemical aspects of detergency. Two model soils, tripalmitin and dotriacontane, have been investigated. Water absorption by the model soils has been monitored, through the change in resonance frequency of the coated crystal, as a function of time of immersion in high purity water solutions. Water and surfactant absorption and the rate of removal of the model soils upon immersion of the coated QCM crystal in aqueous surfactant solutions have also been monitored. Specifically, results obtained with the surfactants pentaethylene glycol mono-n-dodecyl ether (C12E5) and octaethylene glycol mono-n-dodecyl ether (C12E8) have shown that the QCM technique can be employed to identify several distinct stages in the soil removal process and to rank surfactants in t...