Enhanced micropollutant degradation over catalyst-free synergistic activation of periodate and persulfate under solar light

Micropollutants are ubiquitous in water sources, posing threats to both human health and ecosystems. Conventional water and wastewater treatment processes are inefficient in micropollutant removal. In this study, the energy-effective and environmentally friendly solar light-driven periodate (PI) and peroxydisulfate (PDS) synergistic activation process (PI/PDS/solar light) is developed for efficient micropollutant decontamination. The PI/PDS/solar light process (0.5 mM PI and 0.25 mM PDS) achieves 100% degradation of 2 ppm CBZ in 15 min with a CBZ degradation rate constant of 0.31 min^-1, which is 6.6 and 13.2 times that of PI/solar light (0.046 min^-1, 0.5 mM PI) and PDS/solar light (0.023 min^-1, 0.5 mM PDS). Mechanistic studies reveal that the enhanced solar light utilization and charge transfer between PI and PDS lead to the synergistic activation of the dual oxidants in the PI/PDS/solar light process, thus promoting micropollutant degradation. Additionally, the scavenging tests demonstrate that ^•OH and SO₄^•- are the dominant radicals for CBZ degradation. Furthermore, the PI/PDS/solar light process exhibits excellent applicability in different types of water sources, where several water components (pH, natural organic matter, and anions) pose insignificant impacts on CBZ degradation. Nonetheless, the developed process still has a disadvantage in that the degradation intermediates of PPCPs may bring potential toxicity. The study offers valuable mechanistic insights into the novel synergistic PI and PDS coactivation process under solar light and highlights the practicability of the developed technique as an efficient strategy for micropollutant decontamination.