Selective separation of ABS/PC containing BFRs from ABSs mixture of WEEE by developing hydrophilicity with ZnO coating under microwave treatment

Abstract

This study reports a simple and facile method to separate plastic wastes of acrylonitrile-butadiene-styrene (ABS) and ABS-based plastics (blends of ABS) in waste electronic and electrical equipment (WEEE) by froth flotation after inducing hydrophilization by ZnO coating under microwave treatment. ABS-based plastics containing brominated flame retardants (BFRs) can release hazardous substances, such as hydrogen bromide and brominated dioxins, during disposal or recycling activities. ABS and ABS-based plastics are typical styrene plastics with similar properties and it is, therefore, difficult to separate them selectively for recycling. We used 2-min microwave treatment to rearrange and change the molecular mobility on the surface of the ZnO-coated ABS with increased hydrophilic surfaces, which eased the selective separation of the ABS/polycarbonate (PC) blend containing BFRs from the remaining plastics. Therefore, the combined ZnO coating and microwave treatments can facilitate the selective separation of ABS/PC blend plastics with a recovery and purity of 100% and 91.7%, respectively, in a short flotation time of 2min. Based on these findings, the combination of ZnO coating-microwave treatment and froth flotation can be applied for the selective separation of ABS-based plastics, leading to improved plastic recycling quality.

Keywords: ABS; ABS/PC blend; Froth flotation; Hydrophilicity; Microwave treatment; Separation.