Simultaneous removal of ceftriaxone sodium and Cr(VI) by a novel multi-junction (p-n junction combined with homojunction) composite photocatalyst: BiOI nanosheets modified cake-like anatase-rutile TiO2

Abstract

In this study, we synthesized a multi-junction composite photocatalyst that combined the advantages of homo- and heterojunctions. This multi-junction structure facilitated the separation of electrons and holes through its multi-step energy level structure. Its photocatalytic performance for simultaneous removal of ceftriaxone sodium and Cr(VI) was investigated. Its photocatalytic performance for simultaneous removal of ceftriaxone sodium and Cr(VI) was investigated. The degradation rate of ceftriaxone sodium decreased slightly and the reduction rate of Cr(VI) greatly increased (by 7.4 times). Through the capture experiments, we found that the main active species for ceftriaxone sodium degradation were h+ and ·O2‐−. When ceftriaxone sodium and Cr(VI) were treated simultaneously, electrons reduced Cr(VI), which decreased the generation of ·O2− and the degradation efficiency of ceftriaxone sodium. Simultaneous removal of ceftriaxone sodium and Cr(VI) effectively increased the utilization of photogenerated electron holes. Finally, the degradation pathway of ceftriaxone sodium was inferred by the main intermediates in degradation process. This work is an example of the construction of composite photocatalysts with high performance for the treatment of wastewater coexisting with organic and heavy metal pollutants.