Flotation separation of hazardous polyvinyl chloride towards source control of microplastics based on selective hydrophilization of plasticizer-doping surfaces

Abstract

As the single largest chlorine source of plastics, hazardous polyvinyl chloride (PVC) has become an increasing environmental concern with the rapid microplastics accumulation. An advanced separation method is advocated to purify waste PVC plastics, optimize physical recycling, and protect aquatic and terrestrial environment safety. In this study, we proposed a novel scheme for the flotation separation of PVC plastics with diverse plasticizer contents (PVCs) via regulating hydrophilicity based on a selective ferric deposition. Rigid PVCs were prone to loading ferric ions and generating hydrophilic shells than flexible PVCs. Plasticizers can diffuse freely through the interior and surface of PVC plastics. Abundant plasticizers thereby overlaid the surface of flexible PVC and shielded PVC matrix from ferric ions. By regulating the ferric concentration, the wettability of PVCs was adjusted to separate rigid and flexible PVCs by froth flotation. Waste PVCs could also be separated from each other through the compound process of ferric deposition and flotation, further confirming its feasibility and stability. Thus far, this study supplies distinctive insights into the wettability regulation of plasticizer-doping PVC surfaces, contributes a pioneering hydrophilization method to PVCs separation and recycling, and mitigates hazardous PVC microplastics by source control.