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

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 PbMoO 4 (NPBC) was developed by combining both strategies. After loading PbMoO 4 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 PbMoO 4 @BC (PBC) to improve its adsorption-photocatalytic performance. NPBC-2, in which the ratio of PbMoO 4 : 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 PbMoO 4, 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 (•O 2 −) 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. • A novel PbMoO 4 @NBC catalyst was synthetic by combing precipitation and calcination. • The N doping shorten the band gap of the PBC. • The N-doped on PBC enhanced separation efficiency of electron-hole pairs. • The N-doped on PBC improved the adsorption capacity and removal efficiency of TC. [ABSTRACT FROM AUTHOR]