Removal Of Herbicide Atrazine By A Novel Biochar Based Iron Composite Coupling With Peroxymonosulfate Process From Soil: Synergistic Effect And Mechanism

Over the past decade, herbicides contaminated soil poses a serious threat to humans and environment. In this study, a novel biochar supported zero valent iron (BC-nZVI) was used as a heterogeneous catalyst activating peroxymonosulfate (PMS) for the removal of herbicide atrazine (ATZ) from soil. The results revealed that the removal of ATZ by BC-nZVI/PMS process was superior to that of BC/PMS or nZVI/PMS process. A synergistic effect between BC/PMS and nZVI/PMS processes has been successfully achieved in BC-nZVI/PMS process, and nearly 96% of ATZ removal was obtained at optimum reaction conditions. BC-nZVI/PMS process exhibited an excellent performace on ATZ removal compared with BC-nZVI/H2O2 or BC-nZVI/persulfate (PS) process. PMS decomposition by BC-nZVI/PMS process was higher than the sum of BC/PMS and nZVI/PMS processes. A low Cu concentration accelerated ATZ removal, and Cu was also effectively immobilized. SO4 center dot- was the predominant reactive oxygen species responsible for ATZ degradation, and OH center dot and O-1(2) also took part in reaction. Four kinds of ATZ degradation products were identified, and ATZ degradation could be achieved through de-alkylation, dechlorination and hydroxylation processes. A reaction mechanism of PMS activation by BC-nZVI was proposed based on the synergistic effect of BC and nZVI. In addition to ATZ, coexisting pollutants such as 2,4-dichlorophenol (2,4-DCP), Cu and Cd were also simultaneously removed from soil.