Removal of solid organic films from rotating disks using emulsion cleaners

Measurements have been made of the rate of removal of a solid organic film (phenanthrene) from the surface of a rotating disk using emulsions containi ng water, the nonionic surfactant Tween 20, and d-limonene as the organic p hase. The results show that phenanthrene removal initially occurs by the up take of phenanthrene into the emulsion drops as small aggregates. Simultane ously, the organic phase penetrates into the phenanthrene film, diminishing the adhesive force between the film and the substrate. After sufficient ti me, the phenanthrene film detaches from the rotating disk surface as a soli d. This detachment mechanism accounts for the vast majority of the phenanth rene removal (similar to 90%). Initial solubilization rates were analyzed u sing two solubilization models. Both models assume that phenanthrene remova l occurs via a mass transfer limited removal of phenanthrene-laden emulsion drops from the phenanthrene film surface into the bulk solution. One model treats the emulsion as homogeneous while the other accounts for the finite size of the emulsion droplets. The latter model was also used to relate th e flux of organic phase impacting the phenanthrene film to the detachment t imes. (C) 2000 Academic Press.