Recovery of Silver From Wastewater by Polydopamine Functionalized Polystyrene Mesoporous Microspheres and Its Secondary Catalytic Application in Dye Removal

Heavy metal and dye pollution are significant environmental challenges that seriously threaten human health and ecosystem balance. This study introduces a new method for recovering Ag + from wastewater and uses the recovered silver for secondary catalytic applications in dye degradation. Polydopamine functionalized polystyrene mesoporous microspheres (PPS-PDA) were prepared using a green mussel chemical method based on monodisperse polystyrene mesoporous microspheres (PPS) with a diameter of approximately 7 μm. According to the results of Brunauer Emmett Teller Analyzer, the average pore size of PPS-PDA is 17.88 nm, the porosity is 0.53%, and the specific surface area is 54.52 m 2 /g. By observing the scanning electron microscope and energy dispersive spectroscopy, PPS-PDA has an adsorption effect on Ag + in silver ammonia solution and can adsorb up to 40% of silver ammonia solution. The catalytic process was monitored by UV–visible light. The adsorbed Ag-supported polydopamine functionalized polystyrene mesoporous microspheres (PPS-PDA-Ag) showed strong catalytic activity in the process of methylene blue reduction, and the catalytic behavior was consistent with the pseudo-second-order kinetic model. The catalyst maintained an efficiency of 85% in 10 cycles, highlighting its potential in sustainable wastewater treatment.