Novel PbMoO4 loaded N-biochar composites with enhanced adsorption-photocatalytic removal of tetracycline

Abstract

Modifying energy band structure and increasing absorption are two efficient strategies to improve the photocatalytic performance of semiconductor photocatalysts. In this study, a novel biochar (BC) based photocatalyst, nitrogen-doped (N-doped) BC based PbMoO4 (NPBC) was developed by combining both strategies. After loading PbMoO4 on poplar sawdust via in situ method, the composites were pyrolyzed in the presence of a certain amount of urea. Nitrogen doping successfully increased the specific surface area and narrowed the bandgap of the composite of PbMoO4@BC (PBC) to improve its adsorption-photocatalytic performance. NPBC-2, in which the ratio of PbMoO4: poplar sawdust was 3:1.6, exhibited excellent adsorption-photocatalytic removal for 40 mg L−1 tetracycline (TC) under visible light and the total removal rate was 88.25%, which was 1.60 and 3.46 folds of that for PBC and PbMoO4, respectively. The adsorption kinetic of TC removal by NPBC-2 fitted well with pseudo fist order models, and the adsorption was dominated by the physical process. Vacancies (h+) and superoxide radicals (•O2−) were the main active species for TC photodegradation. In addition, after 5 cycles, the composite still exhibited high ability for TC removal. Therefore, N-doped BC based photocatalysts provided a feasible and effective way for the remediation of organism-contaminated water.