Sequencing batch photocatalytic H2O2 production over a magnetic resorcinol–formaldehyde polymer for on-site water purification by UV light irradiation

Abstract

A self-maintainable decentralized water treatment system is appealing, while avoiding chemical addition is the prerequisite to realize it. As a widely used chemical in advanced oxidation processes (AOPs), H₂O₂ can be produced via photocatalysis. However, there remain challenges to use the photocatalytically produced H₂O₂ for water purification in a continuous operation, which requires that the produced H₂O₂ solution has no impurity and the catalyst powder is easily separable. We realized this by photocatalytic H₂O₂ production over magnetic separable photocatalytic microspheres through a sequencing batch process and coupling with ultraviolet C (UVC)/H₂O₂ for micropollutant removal via a flow-through operation. The photocatalysts were synthesized by in situ growth of a resorcinol–formaldehyde (RF) copolymer on Fe₃O₄@SiO₂ microspheres, which can convert earth-abundant water and air into H₂O₂ under visible light irradiation. A clean H₂O₂ solution was produced at 100 μmol h⁻¹ g⁻¹ over magnetic photocatalysts and separated by using an external magnetic field. The on-site utilization of the obtained H₂O₂ solution was realized via UV light irradiation. This work provides a rational design of easily separable photocatalysts for H₂O₂ production, and offers insights for development of water purification processes with zero chemical addition and maintenance.