A Systematic Review on Persulfate Activation Induced by Functionalized Mesoporous Silica Catalysts for Water Purification

The eco-toxicological impacts caused by organic pollutants in aquatic environments have emerged as a global concern in recent decades, resulting from the potential hazards they present to ecosystem integrity and human health. Decorating active components on mesoporous silica is considered a popular approach by which to obtain synergistic effects in persulfate activation for sustainable water decontamination. However, at present there has been no review focusing solely, specifically and comprehensively on this field. Therefore, this paper places an emphasis on the latest research progress on the synthesis and physicochemical properties of functionalized mesoporous silica materials as well as their catalytic performance. The preparation methods included co-condensation, impregnation, grinding–calcination, hydrothermal synthesis and chemical precipitation, and their synthesis parameters played a major role in the characterization of materials, thereby affecting pollutant elimination. Metal redox cycles, nonmetallic activation and confinement effects contributed to persulfate activation. Targeted pollutants were degraded via radical pathways, non-radical pathways, or a combination of the two. The effects and causes of operational conditions (catalyst and persulfate dosage, initial pollutant concentration, temperature, initial pH, co-existing anions, and natural organic matter) varied across the degradation systems, and they were categorized and summarized in detail. Furthermore, functionalized mesoporous silica presented excellent reusability, stability and applicability in practical application. Finally, current potential directions for further research and sustainable development in this field were also prospected. This critical analysis aims to fuel the evolution of functionalized mesoporous silica catalyst-driven persulfate system application in water treatment and to bridge prevailing knowledge gaps.