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Selective surface modifi cation of polyvinyl chloride (PVC) by ozonation was evaluated to facilitate the separation of PVC from other heavy plastics with almost the same density as PVC, especially polyethylene terephthalate (PET), by the froth fl otation process. The optimum froth fl otation conditions were investigated, and it was found that at 40°C, 90% of PVC and PET plastics fl oated. The bubble size became larger and the area covered with bubbles on the plastic surface was reduced with increasing temperature. Optimum PVC separation was achieved with the fl otation solution at 40°C and mixing at 180-200 rpm, even for sheet samples 10 mm in size. Combined treatment by ozonation and froth fl otation is a simple, effective, and inexpensive method for PVC separation from waste plastics.

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The surface modification mechanism of polyvinyl chloride (PVC) by ozonation was investigated to study the selective hydrophilization of PVC surface among other plastics. Infrared analysis confirmed the increase of hydrophilic groups. XPS analysis revealed that the increase was due to the structural change in chlorine group in PVC to hydroxylic acid, ketone, and carboxylic groups by ozonation. This chemical reaction by ozone could occur only for polymers with chlorides in its structure and resulted in the selective hydrophilization of PVC among various polymers.