Abstract

Significance Advanced oxidation technology has garnered significant scientific and technological interest due to its excellent physical, mechanical, and chemical properties, making it highly promising for applications in water and air pollution treatment. Specifically, photocatalysis and persulfate activation catalysis stand out as highly effective methods for addressing environmental challenges, such as heavy metal ion removal, organic wastewater purification, and degradation of harmful airborne organic compounds. These techniques are widely recognized for their simplicity, high efficiency, and cost-effectiveness. However, despite these advantages, limitations remain, such as easy aggregation and instability of catalysts, which hinders the optimization of oxidation processes, driving the exploration of alternative catalytic materials. Among all the candidates, diatomite-based composites have emerged as a popular choice for catalyst substrates. Derived from natural minerals, diatomite composites demonstrate excellent stability, high specific surface area, and superior chemical activity, making them a research hotspot in organic wastewater treatment over the past decade. These properties also position them as a transformative solution for enhancing the efficiency and sustainability of water treatment processes.

Progress In photocatalysis and persulfate activation, various modification methods have been employed to optimize the structure and properties of diatomite composite catalysts. In photocatalysis, diatomite composites typically incorporate bismuth-based semiconductors, TiO₂, graphitic carbon nitride (g-C₃N₄), and metal compounds, synergistically enhancing photocatalytic performance. In persulfate activation, diatomite composites primarily serve as a support for metal bases, including cobalt (Co), iron (Fe), manganese (Mn), and cerium (Ce). As a photocatalytic material, diatomite forms an adsorption-photocatalytic collaborative system, providing abundant active sites, enhancing light absorption, and improving photocatalytic efficiency by inhibiting electron-hole recombination. As a carrier for bimetallic persulfate activation, diatomite synergizes with various transition metals, preventing metal ion agglomeration and leaching. Its unique interconnected porous structure and oxygen vacancies ensure low charge transport resistance, while creating numerous exposed edges and sharp corners. This structural arrangement significantly expands the material's accessible spaces and increases the number of active edge sites. Additionally, its open diffusion channels and abundant hydroxyl groups reduce the migration distance of reactive oxygen species (ROS), enhancing organic pollutant degradation efficiency. Diatomite composites exhibit remarkable degradation performance for various organic pollutants, including dyes, pesticides, antibiotics, and endocrine disruptors, achieving degradation rates of over 80%. Moreover, these composites demonstrate excellent recyclability and stability, making them highly suitable for practical applications. Their unique properties also facilitate their separation and recovery from treated water, ensuring sustainability and cost-effectiveness.