Efficient peroxydisulfate activation with nZVI/CuO@BC nanocomposite derived from wastes for degradation of tetrabromobisphenol A in alkaline environment.

Peroxydisulfate (PDS) is a promising oxidant for sulfate radical based advanced oxidation processes (SAOPs), however its efficient activation is still a challenge. In this study, biochar-supported nano-zerovalent iron (nZVI) and copper oxide (CuO) nanocomposite (nZVI/CuO@BC), derived from low-cost wastes including scrap iron filings, copper leaching solution and corn stalks, was successfully fabricated for PDS activation to enhance tetrabromobisphenol A (TBBPA) degradation in alkaline environment. Under the conditions of 100 mg/L nZVI/CuO@BC, 0.2 mM PDS, pH 8.0 and 25 °C, 86.32% of PDS was activated and 98.46% of TBBPA was degraded within 45 min in nZVI/CuO@BC-activated PDS system. When the PDS concentration was 2 mM, the nZVI/CuO@BC-activated PDS system realized efficient debromination and mineralization of TBBPA at the ratio of 79.12% and 79.36%, respectively. The results of EPR studies and radical scavenger experiments revealed that both hydroxyl radical (·OH) and sulfate radical (SO) were responsible for TBBPA degradation. The nZVI could active PDS indirectly through electron transfer mechanism and exhibited synergistic effects with CuO on PDS activation. Furthermore, the nZVI/CuO@BC-activated PDS system showed good potential to degrade TBBPA in real water environment. Therefore, nZVI/CuO@BC could be a novel strategy for efficient PDS activation and TBBPA degradation in alkaline environment.