Recent advancements on elimination of emerging contaminants by homogeneous metal-catalyzed sulfur(Ⅳ) oxidation

Abstract

The presence of emerging contaminants (ECs) in the environment poses a significant threat to water security and human welfare, which is an urgent problem to solve. Sulfur(Ⅳ) (S(Ⅳ)) combined with metal ions advanced oxidation technologies (AOTs) can generate diversified reactive oxygen species, showing great performance for ECs treatment. Importantly, the application of S(Ⅳ) can be considered a process of using waste to treat waste. This paper is aimed at reviewing the latest progress on ECs elimination by homogenous metal-catalyzed S(Ⅳ) oxidation. The in-depth mechanism analyses and enhancing strategies on S(Ⅳ) activation were summarized. Subsequently, the pivotal influence factors, such as pH, dissolved oxygen (DO), and S(Ⅳ) concentration for ECs removal performance were analyzed. And intermediate toxicity evaluation of ECs was conducted. This study also indicated that intermediate toxicity effectively decreased after application by such processes. Additionally, some helpful suggestions and prospects were proposed to guide the development direction for metal-catalyzed S(Ⅳ) processes. For instance, most current research is confined to the laboratory scale, necessitating the promotion of translating research outcomes into practical applications. Meanwhile, future studies should focus on improvement on paraments optimization via machine learning. A research gap has been identified for investigating the high-valent metal-oxo intermediates in such processes, especially for ECs degradation. This review is hopeful for promoting understanding and application of metal-catalyzed S(Ⅳ) processes for water purification.