Separation of polyvinyl chloride (PVC) from automobile shredder residue (ASR) by froth flotation with ozonation

Abstract

The purpose of this study is to develop froth flotation to separate polyvinyl chloride (PVC) from automobile shredder residue (ASR) plastic mixtures of variable composition. Some polymers in ASR polymer mixtures have similar density and hydrophobicity with PVC and thus selective flotation of PVC from ASR polymer mixtures cannot be achieved. The present study focused on the surface modification of PVC with ozonation, and then the modified PVC can be separated from other polymers by the following froth flotation. The results of this study indicate that the selective recovery of PVC from real ASR polyethylene tetra pethelate (PET), polymethyl methacrylate (PMMA), polybutyl methacralate (PBMA), ethyl acrylate (EA), polycarbonate (PC) and rubber mixtures can be accomplished in a three-step process involving a gravity separation, ozonation and froth flotation. The rubber was removed from other heavy ASR (PVC, PET, PMMA, PBMA, EA and PC) polymers by froth flotation without mixing. It was found that ozonation process produced the desired difference in contact angle required (from 89.5 to 73.0°) for separation of PVC from other heavy ASR polymers, whereas the contact angles of other polymers was slightly decreased. The most of the load ASR, i.e. about 72.4% is floated away and 27.6% was settled down. The highest component 96.7% of PVC was recovered in the settled fraction. As a result of this research effort, the surface modification of PVC with ozonation can be efficiently useful to separate the PVC from other similar density ASR mixed polymers.