Composite catalyst regenerated from spent Cu-Bi-spinel adsorbent and its Fenton-like photocatalysis mechanism for efficient removal of sulfamethoxazole

Reutilization of spent adsorbent by converting the adsorbed organic pollutants into carbon matrix has attracted more attention in recent years, which delivers a greener way for the preparation of catalysis and environment remediation. In this work, CuBi 2 O 4 after adsorption of pollutant sulfamethazine was further transformed to a photocatalyst CBO-WC500 with high catalytic efficiency for degradation of typical pharmaceuticals. The XAFS analysis proved that Cu-C chemical bond was constructed during the preparation process. The obtained CBO-WC500 was applied to remove sulfamethoxazole (SMX) through photocatalytic Fenton-like reaction, and removal efficiency reached 88.9 % after 60 minutes with the initial 5 mg•L −1 SMX and 0.2 g•L −1 catalyst in peroxymonosulfate (PMS) system. The results showed that the introduction of carbon stem from waste improved separation of photo-generated carriers and electron transfer capability, thus more photo-induced electrons could participate in reaction with PMS. Moreover, Cu(I) and Cu(II) in CBO-WC500 with Cu-Bi-spinel structure played a vital role in PMS activation. Led by electron transportation, reactive species ( 1 O 2 , •OH, SO 4 •- ) originated from PMS contributed to degradation of SMX, and degradation pathway of target pollutant was proposed based on analysis of intermediates. Removal efficiency of CBO-WC500 for SMX kept stable after several cycles’ utilization, and it also showed decent eliminating performance of mixed pollutants in different water matrix. This study has provided a potential way for resource reuse of adsorbed pollutant and realizing reutilization of spent adsorbent as photocatalyst with higher efficiency.