Hybrid selective surface wettability separation of chlorinated plastics from E-waste shredder residue = Hybrid selective surface wettability separation of chlorinated plastics from E-waste shredder residue

다국어 초록 (Multilingual Abstract)

The presence of chlorinated/brominated halogenated plastics in automobile and electronic waste shredder residue (ASR/ESR), can contribute to the formation of hazardous chlorinated/brominated dioxins when subjected to incineration or thermal recycling. Treatment by a nanometallic Ca/CaO composite has been found to selectively hydrophilize the surface of polyvinyl chloride (PVC), enhancing its wettability and thereby promoting its separation from E-waste plastics by means of froth flotation. The treatment considerably decreased the water contact angle of PVC, by about 18°. The SEM images of the PVC plastic after treatment displayed significant changes in their surface morphology compared to other plastics. The SEM-EDS results reveal that a markedly decrease of [Cl] concentration simultaneously with dramatic increase of [O] on the surface of the PCV samples. XPS results further confirmed an increase of hydrophilic functional groups on the PVC surface. Froth flotation at 100 rpm mixing speed was found to be optimal, separating 100% of the PVC into a settled fraction of 96.4% purity even when the plastics fed into the reactor were of nonuniform size and shape. The total recovery of PVC-free plastics in E-waste reached nearly 100% in the floated fraction, significantly improved from the 20.5 wt% of light plastics that can be recovered by means of conventional wet gravity separation. The reagent employed during treatment is very small, and further surface contaminant removal on recycled E-waste plastics surfaces makes the developed process simple, effective and green.