Synergic effect of CuS and MgO for boosting adsorption-photocatalytic activity of S-doped biochar

Adsorption coupled with photocatalysis is a promising route to remove dyes from wastewater. Biochar was modified with S, CuS, and MgO (CuS-Mg/S-BC) through one-pot sulfurization to boost the adsorption and photocatalytic removal of rhodamine B (RhB). The abundant functional groups as well as vacant sites formed at the junction interface among S-doped biochar, CuS, and MgO favored RhB adsorption and photon capture, and this tight interface increased the separation and transfer of photoinduced e(-)-h(+) pairs. Hence, CuS-Mg/S-BC exhibited greater removal efficiency than S-doped biochar, 2-CuS/S-BC (The biochar is loaded with 5 % CuS), and b-Mg/S-BC (The biochar is loaded with 5 % MgO). Langmuir and second-order models well described the adsorption isotherms and kinetics, respectively of CuS-Mg/S-BC composites. 2 b-CuS-Mg/S-BC (Biochar is loaded with both 5 % CuS and MgO) exhibited a removal efficiency of 95.70 % within 120 min, and qe estimated from the second-order model was 981.67 mg g(-1). For a 220 mg L-1 RhB solution, the removal efficiency and the adsorption efficiency decreased from 95.70 % to 87.01 % and from 83.54 % to 76.17 %, respectively, after seven cycles.

Automated summary

CuS-Mg/S-BC composites modified by one-pot sulfurization exhibited higher removal efficiency in adsorption and photocatalytic removal of dyes, thanks to the functional groups and vacant sites formed at the interface for enhanced adsorption and photon capture.