This work examines the cleaning of organic films composed of a primary component (abietic acid) mixed with trace amounts of a second contaminant (benzoic acid). Films were removed from a rotating disk in the presence of aqueous solutions of two poly(ethylene glycol) alkyl ether surfactants: C12E5 and C16E8. With C12E5 the abietic acid was removed from the disk in three successive cleaning stages-solubilization, shear removal, and rollup-whereas the benzoic acid was almost completely removed during the initial solubilization stage. Also, with C12E5 the results show that the micellar solubilization rate of the trace contaminant is directly proportional to its concentration in the film. The ratio of the molar removal rates of benzoic acid to abietic acid with C12E5 is an order of magnitude greater than the ratio of the mole fractions of the two components in the contaminant film. Solutions of C16E8 removed the abietic acid by only the solubilization and rollup stages. The ratio of the molar removal rates of benzoic acid to abietic acid with C16E8 was equal to the ratio of the mole fractions of the two components in the contaminant film. A mathematical model is proposed to quantify the simultaneous removal of benzoic acid and abietic acid during the micellar solubilization stage. The model takes into account the mass-transfer rate between the film and the bulk solution, as well as the micellization rates at the film/surfactant solution interface. The model adequately represents the experimental data.
ASJC Scopus subject areas
- Chemical Engineering(all)
- Industrial and Manufacturing Engineering