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Compound tribo-electrostatic separation for recycling mixed plastic waste

Li, Jia, Xu, Zhenming
Journal of hazardous materials 2019 v.367 pp. 43-49
granules, organochlorine compounds, plastics, poly(vinyl chloride), polypropylenes, polystyrenes, recycling, styrene, wastes
To separate mixed plastic wastes into pure components can hugely elevate their reusable value and reduce the environmental risks. This study proposes a compound process to handle mixed plastics wastes. The study used mixed plastic granules of polypropylene (PP), acrylonitrile butadiene styrene (ABS), poly vinyl chloride (PVC), and polystyrene (PS) as the feeding material. Vibrating and cyclone tribo-chargers were used to find charge performance of different granules. In vibrating tribo-charger the biggest gap of charge/mass ratio (CMR) between different granules was 3.63 nC/g, when the wall material was ABS. In cyclone tribo-charger, this value was 8.37 nC/g. Then two modes of compound separation were proposed to separate mixture. In mode-1, only one kind of material was separated from mixed granules each time. In mode-2, the mixed granules were separated to two groups. The separation results showed that the average separation efficiency (Es) of mode-1 was 72.44%, the average Es of mode-2 was 65.18%. The mixed plastic particles can be potentially separated by changing their triboelectric series as long as their CMR have significant differences.