A Study On Water Remediation By Biochar Supported Nano Zero Valent Iron

Nanoscale zero-valent iron(nZVI)is a widely used reactive agent in water pollution remediation.In this study,nZVI loaded on biochar(BC-nZVI)was produced by liquid phase reduction method to improve the dispersity of nZVI.A series of characterization and analysis was conducted to compare the physical and chemical properties of nZVI and BC–nZVI.Then BC-nZVI catalyzing sodium persulfate was used for the removal of trichloroethylene and hexavalent chromium.According to the results of SEM,XRD and XPS characterization,nZVI was successfully loaded on the surface of biochar through liquid phase reduction.nZVI was composed of a zero-valent state iron core with a thin oxidized shell.Zeta potential and sedimentation curves indicated that the surface charge was increased after modification,and thus the increased electrostatic repulsion enhanced the stability.The specific surface area test showed that the presence of biochar can effectively increase the surface area of nZVI.Compared with nZVI and BC,BC-nZVI showed the better adsorption ability of heavy metal Cr(VI).At low concentration of Cr(VI)(20 mg/L),the removal effeciency of Cr(VI)by BC(CS)-nZVI,BC(CC)-nZVI can reach 100%,respectively.And the reaction rate of BC-nZVI was significantly faster than the pristine nZVI,which because that nZVI was well dispersed on the biochar to increased the contact area of nZVI and contanminant.When the concentration of Cr(VI)increased to 50 mg/L,BC(CS)-nZVI showed obvious advantages that the removal rate was up to92.8% at 2 h and finally removed completely.Comparing the raw material of biochar,corn straw has more advantages.Sodium persulfate was activated by BC-nZVI and Hydrothermal carbon loaded nZVI,respectively,for TCE and Cr(?)pollutants remediation.Compared with nZVI and BC,BC-nZVI could activate sodium persulfate faster by producing SO4-to dechlorinate TCE.and producing chloride ion.When the concentration of sodium persulfate was high enough,the reaction efficiency could reach 100% in 6 h.Low concentration of Cr(?)could not affect the degradation of TCE by BC-nZVI.Hydrothermal carbon loaded nano iron could also activate sodium persulfate and remove TCE and Cr(?)pollutants,which perfomed better than nZVI and HC.But the dose of PS was significant.Therefore,BC-nZVI/PS system has a wide application prospect in the treatment of combined groundwater pollution due to its excellent catalytic oxidation capacity and reductive adsorption capacity.