Multifunctional Magnetic Porous Microspheres for Highly Efficient and Recyclable Water Disinfection and Dye Removal

It is of considerable significance to develop efficient and robust water purification technologies because of the increasing population and the serious water pollution. Herein, we proposed a facile strategy to synthesize a multifunctional water treatment agent, via one-pot grafting of antibacterial polyhexamethylene biguanide (PHMB) onto porous microspheres (PMSs) constructed by poly(N-isopropylacrylamide-co-methacrylic acid) and Fe₃O₄ nanoparticles. The resulting PHMB-g-PMS exhibited prominent disinfection performance and a high adsorption capacity for dye pollutants. The minimum inhibitory concentrations (MICs) of the microspheres against Staphylococcus aureus and Escherichia coli were 2.0 and 3.9 μg/mL, respectively. The adsorption capacities for Congo red (CR) and acid fuchsin (AF) were 2422 and 885 mg/g, respectively, and the adsorption processes of the microspheres toward CR and AF match with the Langmuir and pseudo-second-order models. Moreover, pollutant-loaded microspheres were readily collected using a magnet and regenerated effectively using NaOH solution. After seven adsorption-desorption cycles, PHMB-g-PMS still showed excellent reusability with 100% inactivation of Escherichia coli and around 80% removal efficiency for AF. In summary, the prepared magnetic porous microspheres exhibit tremendous potential for removing multiple contaminants by an all-in-one process.