Evaluation of potassium ferrate activated biochar for the simultaneous adsorption of copper and sulfadiazine: Competitive versus synergistic

Combined pollution caused by organic pollutants and heavy metals pose a significant challenge to the adsorption process . In this study, iron-modified biochar (Fe-BC) was prepared by using ferrate (K 2 FeO 4 ) and wheat stalk as the precursors for the adsorption of copper (Cu 2+ ) and sulfadiazine (SDZ), especially under combined pollution scenarios. Iron modification not only enlarged the surface area but also loaded iron oxide nanoparticles on biochar surface. Accordingly, Fe-BC exhibited better adsorption capability of Cu 2+ and SDZ than the pristine biochar (BC). The corresponding maximum adsorption capacities of Fe-BC 700 were 46.85 mg g −1 and 45.43 mg g −1 towards Cu 2+ and SDZ, respectively. Interestingly, the adsorption was elevated in binary-pollutants system, suggesting a synergistic effect, which was probably attributed to the mutual bridging effects and complexation between Cu 2+ and SDZ. The loaded iron oxide particles could serve as a physical barrier to separate the adsorptions of Cu 2+ and SDZ and thus inhibited the competitive adsorption. Meanwhile, theoretical calculation demonstrated that sulfonamide group was the most probable binding site. Columns packed with Fe-BC 700 showed better performances for Cu 2+ and SDZ removal in binary system (635.73 BV for Cu 2+ and 4846.26 BV for SDZ) than in single systems (571.60 BV for Cu 2+ and 3572.06 BV for SDZ), which was consistent with batch adsorption experiments. These results demonstrated the potential application of Fe-BC 700 for simultaneous adsorption of Cu 2+ and SDZ and provided a cost-effective way for the remediation of organic and inorganic pollutants.