Loading Cu-doped magnesium oxide onto surface of magnetic nanoparticles to prepare magnetic disinfectant with enhanced antibacterial activity.

In this article, Cu-doped magnesium oxide was loaded onto the surface of FeO magnetic nanoparticles via a hydrophilic carbon intermediate layer to synthesize FeO@C@MgO-Cu magnetic composite. The potential application as disinfectant in water purification was investigated by examining the antibacterial activity of the FeO@C@MgO-Cu composite toward Gram negative Escherichia coli and Gram positive Staphylococcus aureus. The practical bactericidal efficiency in inactivation experiment was also studied and the copper doping amount was optimized. The results show that the as-obtained magnetic composite, with good dispersion and typical multilayer structure, exhibited high antibacterial activity to both strains and the Cu-doping improved the antibacterial performance significantly. Moreover, an increasing bactericidal ability of the nanocomposite was observed with the increasing Cu-doping amount and 312.5mgL of FeO@C@MgO-Cu disinfectant with a 1.5% Cu-doping amount (wt% of MgO) could inactivate 99% of the tested bacteria in normal saline solution within 60minutes. The FeO@C@MgO-Cu composite, with a high magnetic saturation value of 29.07emug, can be readily recovered from matrix solution for reuse with an external magnet, which simplified the disinfection operation greatly and avoided the waste of disinfectant.