In-situ synthesis of NiS-modified MgO/S-doped biochar for boosting the adsorption-photocatalytic activity

Biochar-based composites have been intensively applied in wastewater treatment. To boost the adsorption-photocatalytic capacity of biochar for dyes elimination, S-doped biochar was commodified by NiS and MgO (NiS-Mg/S-BC) via the one-pot sulfurization at high temperature. The functional groups in NiS-Mg/S-BC provided the abundant vacant sites for RhB adsorption and photocatalysis, and the junction interface among NiS, MgO, and S-doped biochar was likely to form the channels for the separation and transfer of photo-induced e-/h+ pairs. NiS-Mg/S-BC presented the better adsorption-photocatalytic capacity of RhB than S-doped biochar, NiS and MgO modified biochar. Langmuir and second-order models well described the adsorption behaviors of NiS-Mg/S-BC. The removal efficiency of optimal 2b-NiS-Mg/S-BC for 400 mg/L RhB solution was 96.98% within 120 min, and its adsorption capacity based on second-order model was 802.49 mg g−1. The photo-corrosion induced to the declined removal efficiency of 2b-NiS-Mg/S-BC to 94.13% after five cycles.