2007 Volume 48 Issue 6 Pages 389-395
The detergency of particulate soil in aqueous solutions was examined by the quartz crystal microbalance (QCM) technique and was discussed on the basis of the surface free energies. The gold electrode and spin-coated film of polyethylene, nylon 6 and cellulose triacetate on the gold electrode of the QCM were used as substrates. As model particulate soils, polyethylene and nylon 12 particles were used. The QCM was perpendicularly immersed in aqueous dispersions of spherical particles to deposit the particles onto the substrate. After pulling the substrates out of the dispersion and drying in air, the substrates were cleaned in aqueous solutions with and without ethanol. The removal efficiency was calculated from the frequency changes of the QCM due to soil deposition and cleaning. The efficiency was dependent on the particles and substrates, and increased by the addition of ethanol in all system. The Lifshitz-van der Waals and acid-base components of the surface freed energy of the soil and substrate were estimated from the contact angles of three probe liquids. The detergency phenomenon in the present system was explained in terms of the free energy change due to soil removal, which was calculated from the surface free energy components.
