Visible-light photocatalysis degradation of enrofloxacin by crawfish shell biochar combined with g-C3N4: Effects and mechanisms

Herein, a new type of photocatalyst, that is biochar/g-C3N4 (BC/CN) composite, was successfully prepared from melamine and waste crawfish shells by a simple thermal condensation process and used to degrade enrofloxacin (ENR) wastewater under visible light. The structure and photoelectrochemical properties of the composites were thoroughly characterized. Results showed that there are obvious synergistic effects between BC and CN present in the composite. When the ratio of BC to CN is 2%, the catalyst (BC/CN-2%) has the best visible-light photocatalytic performance. The •O2− radicals were the main oxidation free radicals responsible for ENR removal and the radicals first attacked the piperazine moiety of the ENR, and further, the whole photocatalytic degradation pathway was proposed. This study provided a promising strategy for the synthesis of photocatalyst materials from waste crawfish shells and their application in the treatment of antibiotic wastewater.