Preparation Of Nanoscale Zero Valent Iron And Restore Performance / Mesoporous Carbon Composite Body

In recent years, Nano zero valent iron (nZVI) was an active popular technology ofenvironmental remediation, due to it has high reactivity and more active sites, so it hasbeen widely used in the field of restoration of contaminated groundwater and soil. nZVIwas defined as particles of zero valent iron with size in the range of1to100nm at leastin one of the three dimensions. Because of this very small size scale, they possess animmense surface area per unit volume, a high proportion of atoms in the surface andnear surface layers, so it can exhibit the ability of quantum effects. But nZVI has astrong tendency to aggregate and may be self-ignite or oxidized when exposed to the air,thus limited its application. To overcome these drawbacks, we proposed to design novelsupported nZVI composites using ordered mesoporous carbons as carrier(nZVI/OMCs).In this paper, nZVI/OMCs composites are prepared by impregnation method andsolution casting method. The nZVI was well dispersed and embedded in the structure ofnZVI/OMCs, the composites can maintain structure of mesoporous be consistent withcarrier material, and it has the advantage in surface area, dispersibility, stability,adsorption properties, reactivity, and reusability. The crystalline states and chemicalproperties of nZVI/OMCs before and after use, and storage for15days in air have notsubstantially changed. The resultant materials were characterized using X-raydiffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption/desorption, thermogravimetry (TG). Cr(Ⅵ) and nitrate are selected as the targetpollutant, the ability of nZVI/OMCs for reducing contaminations was thereforeinvestigated. The results showed that:(1) Ordered mesoporous carbon material was prepared by using SBA–15astemplate. The SBETof OMCs is1277.91m2/g, the arrangement of pore structure ofOMCs is tight and orderly, and OMCs has a uniform pore size of about3.6nm.nZVI/OMCs composites were prepared by carbothermal reduction solution castingmethod. Results found that due to limit effect of pore size of template agent SBA-15, particle size of nZVI was controlled effectively. A small amount of γ-Fe2O3wasappeared in nZVI/OMCs composites, which indicates that reaction of carbothermalreduction was not completely.(2) nZVI/OMCs composites were prepared by carbothermal reductionimpregnation method. Results found that optimized conditions for synthesis ofnZVI/OMCs were iron/carbon ratio of3:1, at800℃for3hours under a N2atmosphere.The iron particles in composites were dispersed in the form of nano zero valent iron,chemical properties of nZVI was stabilized. With increasing the dosage of iron surfacearea and average pore diameter had a decreasing trend.(3) Reduction of Cr(Ⅵ) and nitrate in water by nZVI/OMCs composites,researches show that nZVI/OMCs have the potential for reduction of Cr(Ⅵ) and nitrate,the removal process was synergistic effect of adsorption and reduction. Removalefficiency of pollutants was improved by increasing dosage of nZVI/OMCs, anddecreasing pH value and concentration. In addition, effect of reduce pollutants ofnZVI/OMCs composite by impregnation method was significantly higher thancomposites by solution casting.