FeS/MgO-biochar composites for boosting the adsorption-photocatalytic degradation of RhB

Biochar-based catalysts derived from biomass waste are potential candidates for environmental protection and sustainable biorefineries, drawing great attention to the circular economy and carbon neutrality. To enlarge the removal capacity of biochar in wastewater treatment, biochar loaded with FeS and MgO (FeS/MgO-biochar) was prepared for the adsorption and photocatalytic degradation of RhB. In contrast with pure biochar, MgO and FeS modified biochar had better adsorption-photocatalytic activity, especially the coupling effect of FeS and MgO for promoting the removal efficiency of FeS/MgO-biochar. It's ascribed to the sufficient active sites at the junction interface among FeS, MgO, and S-doped biochar favoring RhB adsorption and electron capture. Notably, the charge carriers were efficiently separated and transferred at the heterojunction interface, enlarging solar light response and utilization. The influences of experimental parameters on the removal activity of biochar-based composites as well as the adsorption-photocatalytic mechanism were discussed. The optimal FeS/MgO-biochar could eliminate 99.13 % RhB within 120 min, while the photo-corrosion induced its declined removal efficiency to 95.87 % after fifth-cycle.