One-Step Synthesis Of Biochar Supported Nzvi Composites For Highly Efficient Activating Persulfate To Oxidatively Degrade Atrazine

Biochar supported nZVI composites (nZVI@BC) have received extensive attention due to their important application potential in the field of environmental pollution remediation. However, one-pot synthesis of nZVI@BC faces challenges. In this study, a type of nZVI@BC was successfully prepared by a simple one-pot method via oxygen-limited high-temperature co-pyrolysis of the mixture of soybean straw powder and Fe2O3. The XRD results showed that in the absence of biomass, Fe2O3 is transformed into Fe3O4 instead of Fe-0. Interestingly, in the presence of biomass, a large amount of Fe-0 and a small amount of Fe3C are formed. Moreover, the as-designed composites could effectively activate Na2S2O8 (PS) promoting the oxidative degradation of atrazine. A series of reaction kinetics in different systems were carried out to explore the effect of synthesis conditions, and reaction parameters on the degradation process of atrazine. And we have obtained a representative catalyst, which was produced by pyrolysis of a mixture of soybean straw and Fe2O3 (mass ratio = 7:1) at 800 degrees C. In the representative catalyst-PS system, the atrazine removal rate was up to 93.8%, and the apparent activation energy (E) was calculated as 83.34 kJ/mol that is lower than that reported previously in heat-activated PS oxidation system of atrazine, demonstrating that nZVI@BC as a catalyst can effectively reduce the reaction activation energy to promote the degradation of atrazine. SO4 center dot-, center dot OH, PFRs and O-1(2) are jointly contribute to the degradation efficiency of atrazine. The oxidation mechanism of atrazine mainly includes 1) alkyl-oxidation, 2) de-alkylation, 3) dehydrogenation, 4) dechlorination hydroxylation, and 5) olefination.