Efficient photodegradation of hexabromocyclododecane leached from polystyrene by biochar and sulfur doped CuO nanocomposite: Optimization factors, kinetics, and photoactivity

Abstract

Herein, efficient degradation of hexabromocyclododecane (HBCD), a persistent organic pollutant using biochar (BC) and S co-doped CuO nanocomposite, has been reported. The nanocomposite was prepared by one-step co-precipitation-based green synthesis using plant extract as surfactant and reducing agent and was well characterized. The maximum degradation of HBCD was observed at 10 mg catalyst loading, basic pH, and 2 mg L−1 of HBCD amount. The photocatalytic performance of BC@S–CuO for HBCD photodegradation was evaluated, and it was found that the Kapp increased in the order of BC@S–CuO (0.495 h−1) > S–CuO (0.385 h−1) > CuO (0.365 h−1). BC@S–CuO demonstrated the highest photocatalytic activity because of its substantial specific surface area and synergistic interactions among S and BC moieties. It achieved HBCD elimination rates of 55% and 92% by photo-adsorptive degradation within 120 min. Meanwhile, the leaching of HBCD from expanded polystyrene (EPS) materials (28–123 ng g−1) underwater with different time intervals and degradation of leachate HBCD were also assessed. It has been reported that BC@S–CuO may be reused and regenerated by washing with distilled water up to seven times after deactivation. The photodegradation was assessed by HPLC analysis, while chemical scavengers were used to support radical pathways. Finally, GC-MS data identified the degradation intermediates by identifying the HBCD degradation pathway. Overall, this work shows that BC@S–CuO has practical application potential in pollution remediation, and studying the leaching of HBCD from EPS materials in an environment matrix should be an essential research priority.