A novel hollow flower shaped Cu₉S₈ antibacterial agent for removing sulfonamide in water environment: effects of composite with magnetic biochar, differential adsorption, and mechanism study

In this study, hollow nanoflower spherical Cu₉S₈ and Cu₉S₈/Fe₃O₄@BC with adsorption and antibacterial properties was prepared by coprecipitation and solvothermal method, respectively. The adsorption results showed that the Cu₉S₈ exhibited excellent adsorption performance on sulfonamide antibiotics (SAs), especially for sulfamethoxazole (SMZ). The optimal addition amount of Cu₉S₈ is 0.2 g, which results in a maximum adsorption capacity of 33.4 mg/g for SMZ within 120 min. The fitting results of adsorption and desorption kinetics and thermodynamics, as well as the conditions such as pH value and ionic strength were compared. It was found that different interactions led to the differential adsorption of SAs by Cu₉S₈. The desorption experiment further elucidated its adsorption mechanism. The large desorption capacity indicates that SAs on Cu₉S₈ can be further recovered and treated. The auto-deposition characteristics of Cu₉S₈ and the hysteresis loop of Cu₉S₈/Fe₃O₄@BC were studied to effectively recover Cu₉S₈ from aquatic environments. Additionally, more than 99% of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were exterminated by Cu₉S₈ and Cu₉S₈/Fe₃O₄@BC within 20 min. The above results suggested that the hollow nanoflower spherical Cu₉S₈ and Cu₉S₈/Fe₃O₄@BC composite materials can provide a new strategy for solving pollution problems and waste treatment.