Recycling technologies for brominated flame-retardant plastics in e-waste

Abstract

With the fast-growing worldwide population and the large use of electronic gadgets, electronic waste (e-waste) plastics—which compose 25–30 % of total e-waste—have become rather common. Landfilled or burned non-biodegradable plastics include hazardous brominated flame retardants (BFRs), which pose hazards to human health and the environment. Thus, methods for sustainable recycling are rather crucial. This work is a comprehensive literature review based on an extensive search across a wide range of major databases and critical screening of the existing studies; no new laboratory experiments were performed. Investigated in this review work are novel methods for recycling e-waste plastics containing BFRs—including solvent extraction, hydrothermal treatment, supercritical CO₂ extraction, microwave-assisted pyrolysis, and catalytic pyrolysis— were reported in this literature. Of these methods, microwave-assisted pyrolysis has shown maximum performance in optimizing material recovery and breaking down BFRs. Across the reviewed studies, it was found that microwave facilitates selective breakdown, improves heating efficiency, and helps to gather important byproducts including hydrocarbons, metals, and bromine compounds, therefore enabling a more sustainable e-waste treatment system. Moreover, this review work offers a complete knowledge of the thermal degradation behaviour of significant BFRs, including hexabromocyclodecane (HBCD) isomers and tetrabromobisphenol A (TBBPA), so evaluating the efficacy of several removal procedures for these hazardous chemicals. Better knowledge of successful BFRs recycling helps researchers to build ecologically viable industrial applications and circular economy solutions. The results motivate resource recovery and minimize the environmental impact of electronic waste disposal, thereby guiding next research and development in e-waste plastic recycling.