Peroxides chemical-free decomposition of PAHs in soil catalyzed by biochar-Fe3P/Fe composites

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous and highly persistent in soil. Owing to the potential adverse effects of peroxides to soil ecosystems, oxidant-free advanced oxidation process (AOP) is highly demanded for PAHs remediation. We utilize the composites of phosphatized sludge biochars and core/shell Fe 3 P@Fe (PSL-Fe 3 P/Fe) as catalysts to decompose PAHs in soil. In a wide range of soil moisture, pyrene, benzo[ a ]anthracene, benzo[ a ]pyrene, indeno[1,2,3- cd ]pyrene, and dibenzo[ a , h ]anthracene are efficiently degraded by PSL-Fe 3 P/Fe within 6 h. For the first time, we find that reactive oxygen species resulting from internal micro-electrolysis (IME) of biochars (cathode) and Fe 3 P@Fe (anode) are sufficient for PAHs degradation. Strong adsorption, excellent electrical conductivity, high potential difference between Fe 3 P@Fe anode and biochars cathode, and acid-microenvironment provided by P 2 O 5 component trigger the remarkable reactivity of PSL-Fe 3 P/Fe. The environmental-benign PSL-Fe 3 P/Fe can eliminate the phytotoxicity of high-level of PAHs (200 mg/kg), recover soil microbial diversity, and promote the growth of lettuce Lactuca sativa .