High efficiency sulfamethoxazole degradation enabled by chlorinated D–A scheme organic photocatalysts

Abstract

Chlorination is an effective strategy to tune the molecular stacking, broaden the absorption spectrum and influence the charge transfer of organic semiconductors. In this study, efficacious and environmentally benign biochar-based D–A heterojunction organic semiconductor photocatalysts were successfully produced by chlorination modification and application of biochar carriers, which were then applied for the first time in antibiotic removal. The champion catalyst (J71:IT-4Cl)@CSC exhibits excellent electron and hole transfer, a wide light absorption range, and an interpenetrating network structure. This ensures not only the number of electron–hole pairs, but also the high separation and transport capacity of the photogenerated carriers. Consequently, a considerable number of free radicals (˙OH and ˙O₂⁻, etc.) were generated, resulting in a high photocatalytic degradation efficiency of 95% of SMX in 30 minutes of light irradiation. Furthermore, the TOC removal rate of this catalytic system reached 94.8%, and the photocatalytic efficiency did not decrease after 30 cycles, indicating that this catalyst is highly reproducible and does not produce insoluble residues. This study demonstrates the impact of chlorinated modification and biochar carriers on the development of highly efficient D–A organic semiconductor photocatalysts, offering a novel approach to the advancement of environmentally benign and economical photocatalysts.