Preparation Of Carbon-Supported Nano-Zero-Valent Iron And Its Application In In-Situ Remediation Of Contaminated Sites

In recent years,in the process of environmental pollution remediation caused by the oil industry,green and sustainable in-situ remediation technology has been favored.Nanoscale zero-valent iron（nZVI）has great application potential in the field of in-situ remediation of contaminated sites due to its unique surface effect and strong reducibility,and has been widely studied in the environmental field.In this paper,the preparation,verification and application of nZVI modified materials were systematically carried out.The research work will help promote the further application of iron-based materials in the field of in-situ remediation of contaminated sites.In this study,nZVI was first synthesized by electric explosion method,and then loaded onto Slipper-modified activated biochar（SAC）by impregnation physical precipitation method to successfully prepare carbon-loaded nano-zero-valent iron material（SAC-nZVI）.SEM results showed that nZVI was successfully loaded onto SAC.The average particle size of nZVI was 80-100 nm,and EDS further verified the uniformity of element distribution.The XRD pattern showed that the SAC was disordered after high temperature activation,and the developed pore structure was formed,and the microcrystalline（002）crystal plane in the disordered graphite-like structure was produced.The high purity nZVI existed on the surface and in the pores of SAC in the form ofα-Fe⁰（110）.The specific surface area of SAC-nZVI was 243.74 m²/g.Secondly,the simulated remediation experiments of composite nanomaterials in groundwater contaminated by hexavalent chromium（Cr（VI））and trichloroethylene（TCE）were carried out,and the removal effect and kinetic analysis of pollutants were systematically studied.Biochar-loaded nano-zero-valent iron（SAC-nZVI）can effectively disperse nZVI and give full play to the dual role of adsorption/reduction of materials.The lower the initial concentration of pollutants,the better the removal effect.Finally,a high-pressure rotary jet in-situ chemical oxidation remediation experiment was designed in a coal gasification industrial site.Naphthalene was selected as the characteristic pollutant,and its concentration exceeded 400 mg/kg at a depth of 3.8～6.5 m.The repair experiment showed that SAC-nZVI could release Fe²⁺stably and prolong the stable reaction time by about 8 h.At 48 h after rotary spraying,the average naphthalene repair value of SAC-nZVI group was 358.6 mg/kg.