Key impact of pretreatment for support coal gangue on pollutants removal efficiencies: Insight to the divergence for peroxymonosulfate activation and adsorption behavior

Coal gangue (CG), the by-product of coal mining and washing, not only monopolizes land resources, but also poses extreme environmental issues. In this work, original CG and CG with pretreatment (CG^⁎) were used as supports to construct the composites CuO/CG and CuO/CG^⁎ for the removal of antibiotics. The matrix (CG or CG^⁎) had a significant impact on the removal efficiencies of the final composites. The optimal CuO/CG composite exhibited about 80 % degradation efficiency toward sulfamethoxazole (SMX) within 10 min in the presence of peroxymonosulfate (PMS), which was about 1.57 times as that of pristine CuO and about 20 % superior than those of CuO/CG^⁎ composites. The optimal CuO/CG^⁎ composite exhibited 90 % of adsorption efficiency toward tetracycline hydrochloride (TC) within 40 min, which was about 6 times that of pristine CuO and 1.5 times that of CG^⁎-500. The mechanism studies indicated that the discrepancy in surface charges resulted in the different catalytic performance of CuO/CG and CuO/CG^⁎. Moreover, the various adsorption efficiencies of CuO/CG and CuO/CG^⁎ were related to the discrepant specific surface area of these two composites. This work provided two excellent composites for removing pollutants from wastewater, especially paid attention to the effect of pretreatment for supports on the removal performance.