2018 Volume 18 Issue 1 Pages 1-11
The removal process of fatty acid in aqueous systems was investigated using well-defined model detergent systems consisting of polymer, carbon, silica, and gold as substrates, and stearic acid as soil. The detergency was evaluated by the quartz crystal microbalance (QCM) technique. The experimental results were discussed based on detergent solution, soil deposited state and surface properties of the substrate. From the QCM frequency change during the soil removal, it was found that in the alkali solution the stearic acid deposited by the Langmuir–Blodgett (LB) method was rapidly removed due to the neutralization, whereas in the anionic surfactant solutions the LB films was removed by the liquid penetration. By comparing the removal efficiencies obtained from the area (evaluated using microscopic image analysis) and the mass (evaluated using QCM method) of soil deposited on the substrate, it was suggested that the nonionic surfactant micelles contributed to the removal of stearic acid.
