Evaluation of detergency for development of the environment-friendly detergent system

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The detergency was evaluated using a model detergent system constructed by the quartz crystal microbalance technique. Polyethylene, nylon or cellulose acetate film was prepared on gold electrodes of the QCM by a spin-coating method. As a model oily contaminant, the Langmuir-Blodgett films of long-fatty acid were deposited onto the QCM. The QCM was ultrasonically cleaned in aqueous solutions and the removal efficiency of long-fatty acid was determined from the frequency change of the QCM. The efficiency was greatest for acetate, followed by nylon, gold and polyethylene. The removal efficiency was found to increase with increasing surfactant or ethanol concentration. In the presence of alkali, the removal efficiency further increased. The removal efficiency had a good correlation with the free energy change due to the penetration of a liquid layer between the long-fatty acid film and the substrate, which was calculated using the contact angles and surface free energies. The QCM was perpendicularly immersed in the aqueous dispersion of polyethylene or nylon particles as a model particulate soil. Apparent equilibrium deposition was large for the polyethylene particle compared with the nylon particle. The deposition drastically decreased by addition of ethanol to the dispersion. The results were discussed on the basis of the extended DLVO theory using the surface free energy components and the electrokinetic potentials. The deposition was found to largely depend on the acid-base interaction.The 172 nm ultraviolet(UV) excimer light was exposed to polyethylene, polypropylene, poly (ethylene terephthalate) and nylon surfaces in ambient air. The wettability increased remarkably by UV treatment of 1 min. The deposition of polyethylene and nylon particles onto the polymer surface was examined in water, water/ethanol mixture, ethanol and n-heptane. A considerable decrease in the deposition due to UV treatment was confirmed in any system.