Exploring the intensified catalytic role of biochar in facilitating advanced oxidation of tebuconazole

Abstract

Biochar (pyrolyzed organic material) has been increasingly recognized for its catalytic role in facilitating the advanced oxidation of emerging organic pollutants. However, the inherent catalytic capacity remains highly uncontrollable, leading to considerable uncertainty when scaling up for real-world applications. This study explores the intensified catalytic role of biochar coated with CaO2 in generating hydroxyl radicals (OH·) and facilitating advanced oxidation of tebuconazole, a prevalent fungicide, tebuconazole was selected as a representative pesticide in agricultural drainage. In addition to evaluating the potential for degradation by advanced oxidation processes (AOPs), the adsorption capabilities of two commercially available biochars, one derived from agricultural waste (ABC) and the other from spruce chips (SBC), as well as their CaO2-coated derivatives (ABC/CaO2 and SBC/CaO2), were also assessed. By taking advantage of the strong adsorption capacity of biochar, and activating AOPs at the adsorption sites by CaO2, this material enables more efficient and targeted removal of tebuconazole. The results indicate that CaO2 coating on biochar promoted over tenfold increase in the generation of OH·, resulting in 99% tebuconazole removal within 10 min. Despite a decrease in adsorption capacity of 40–50% resulted by CaO2 coating, the 10-minutes overall pesticide removal performance was significantly enhanced. The catalytic potential of biochar is closely related to its surface chemical properties, particularly the presence of persistent free radicals which can be regenerated. This research paves a new way for employing CaO2-enhanced intensified biochar in agricultural mitigation measures.