Boosting advanced oxidation processes by biochar-based catalysts to mitigate pesticides and their metabolites in water treatment: A meta-analysis

In order to boost the performance of water treatment in removing organic micropollutants, biochar as an environmental-friendly and sustainable carbonaceous material has been increasingly utilized as a catalyst in advanced oxidation processes (AOP). The main idea behind this research was to unlock the potential of biochar-based catalysts as (i) persulfates and periodate activators and (ii) photocatalyst for mitigating pesticide and intermediate compounds in water treatment. The conducted meta-analysis provides for the first time objective and quantitative overview of the current state of research on biochar-based catalysts application in AOP, surpassing the limitations of conventional qualitative reviews. This paper systematically evaluates the influence of different factors on the weighted degradation efficacy (WDE) achieved by both studied groups of AOP, based on the data extracted from 38 studies conducted in the period 2016–2023. The most of meta-analyzed studies (74 %) were published during 2021–2023 covering EU Water Framework Directive priority substances and emerging contaminants. The meta-analysis revealed the high heterogeneity within the results of certain groups (p=0.05), indicating the statistically significant influence of the biochar-based catalyst properties, target compound characteristics, pH and water matrix on WDE. The most effective pesticides/intermediate compounds degradation enabled systems containing metal and heteroatom co-doped biochar (e.g. FeS@BC/PMS, S-nZVI@BC/PS) or multicomponent heterojunction (95–99 % WDE with 95 % confidence interval), and decreased under alkaline conditions and in wastewater. The outstanding catalytic performance of biochar application has been confirmed within the pH 5–8 range, demonstrating significant potential in AOP water treatment.