Biochar-based catalysts: an efficient and sustainable approach for water remediation from organic pollutants via advanced oxidation processes.

Water contamination by hazardous organic chemicals, including pharmaceuticals, pesticides, and dyes, is a growing environmental concern due to their persistence, low biodegradability, and toxic effects on aquatic ecosystems and human health, even at trace concentrations. Thus, it is important to remove the organic pollutants before discharge into the environment. Various techniques, including degradation, adsorption, and membrane separation, have been utilized for organic contaminant removal. Among them, advanced oxidation processes (AOPs) have proven to be highly effective for water treatment. Biochar has emerged as a sustainable catalyst in AOPs for organic pollutant removal from water, offering several advantages over traditional methods. Its low cost, low toxicity, high surface area, porosity, and varied active sites contribute to its effectiveness. This review explores various biochar production and modification methods, focusing on its role as an activator in both radical and non-radical AOP pathways. It also discusses the mechanisms by which biochar generates reactive species in AOPs. The choice of biomass feedstock and pyrolysis conditions, including temperature and residence time, plays a critical role in determining activation efficiency. Combining different AOPs has shown potential for developing efficient hybrid technologies. Although research on biochar catalytic performance in AOPs has progressed, the field remains at an early stage, requiring further advancements for large-scale application and commercialization. This review highlights key aspects, emerging perspectives, and challenges in the removal of organic pollutants via AOPs using biochar as an activation catalyst, offering insights for future research on the development, regeneration, and scaling of biochar-based AOPs for commercial applications.