Bi-functional adsorption-photocatalysis activity of Ag2S-MgO/S-doped biochar heterojunction for cationic dye removal

[Display omitted] •S-doped biochar was modified by Ag2S and MgO for boosting adsorption-photocatalytic activity.•The adsorption activity of Ag2S-MgO/S-BC was better than its photocatalytic activity.•Langmuir well fitted with the adsorption isotherms of Ag2S-MgO/S-BC.•Second-order model well describes with the adsorption kinetics of Ag2S-MgO/S-BC. S-doped biochar was co-modified with Ag2S and MgO (Ag2S-MgO/S-BC) for enhancing adsorption-photocatalytic performance in RhB elimination. The prepared Ag2S-MgO/S-BC heterojunctions were better for adsorption-photocatalytic removal of RhB as compared to Ag2S and MgO alone for S-doped biochar modifying. Langmuir and second-order models well described the adsorption isotherms and kinetics of Ag2S-MgO/S-BC, respectively. The adsorption-photocatalytic elimination of RhB over optimal 4-Ag2S-MgO/S-BC was reached to 97.60 % under solar-light irradiation within 120 min, and the photo-corrosion resulted the declined removal efficiency of RhB to 91.87 % after five cycle times. Ag2S-MgO/S-BC was thus the super candidate for adsorption and photocatalytic application in wastewater treatment.