Sulfur-doped zero-valent iron supported on biochar for tetracycline adsorption and removal

BM-S/ZVI@BC was further synthesized from common agricultural waste maize straw and applied to the adsorption of aqueous tetracycline using a simple ball milling method. SEM, XRD, FTIR, and XPS were used to characterize the structural features and surface properties of BM-S/ZVI@BC. The effects of time, temperature, pH, and interfering ions on the adsorption were investigated, and the adsorption performance and possible mechanisms of BM-S/ZVI@BC on tetracycline were explored. The results showed that the adsorption of tetracycline by BM-S/ZVI@BC was more inclined to acidic conditions, The higher the temperature, the better the adsorption of tetracycline, and the maximum saturation adsorption capacity of BC/S/Fe-0 in the optimum ratio of 2:1:1 was up to 505.68 mg.g(-1) at a temperature of 313 K, and the adsorption process was both physical and chemical. The electrostatic interaction, hydrogen bonding, pi-pi stacking, and complexation are the main mechanisms of tetracycline adsorption by BM-S/ZVI@BC. BM-S/ZVI@BC had excellent oxidation resistance and good adsorption performance for tetracycline after aging in the air (60 d) and water (120 h). BM-S/ZVI@BC maintained a high adsorption capacity after five times of reuse and had a good removal capacity for tetracycline in different water bodies. In conclusion, BM-S/ZVI@BC had a good application prospect for tetracycline removal in water.