Preparation Of HJ Clay Supported Nanoscale Zero-valent Iron And Its Application Research

In recent years, Nanoscale zero valent iron has been widely used in the removal of pollutants such as organic pollutants, heavy metals and environmental restoration, etc.For its superior performance in addressing the environmental problems,it has gained widespread concerns in environment field. However, the nZVI can easily lead to reunion due to the nano zero valent iron particles’ magnetic attraction itself, which reducing the effective contact areas between the adsorption points of nanoscale zero valent iron particles and the pollutants. As a result,on one hand,there is a decline in the efficiency of pollutant degradation.On the other hand, the reunion is not conducive to nanoscale zero valent iron in the water environment and soil mobility, as well as not conducive to environmental pollution remediation. Thus how to improve the repair performance of nanoscale zero valent iron and stability is currently a hot research in this field.Meanwhile, studies have shown that nano zero valent iron particles has a strong reduction and can easily be oxidized. Using nano zero valent iron alone for some organic compounds such as POPs can not get a good removal effect.And there is a possibility that more toxic products were transformed in the course of the reaction.So the modification technology towards nanoscale zero valent iron is designed to delay the reduction of activity, and make full use of its reductive performance to remove the target pollutants.According to current research, nanoscale zero valent iron supported on the materials which have large surface areas or good adsorption properties is a widely used.The purpose of the above modification is to increase the specific surface area of iron nanoparticles and take full advantage of its reactivity. As a result, the degradation efficiency of target contaminants is improved.In this paper, Hangjin clay, nano zero valent iron as the raw material, the composites were synthesized by using the liquid-phase reduction method.Nano zero valent iron loaded onto Hangjin clay provided us a cheap and high efficient nano-iron composite material, which has a good effect on the decolorization of the Methyl orange and the removal of Hexavalent chromium.Firstly,Through the means of XRF, XRD, SEM, BET and other means to characterize the support material Hangjin clay, and leaching experiments were made about its heavy metals.The results showed that the main chemical composition of Hangjin clay including SiO2, Al2O3, Fe2O3, MgO, CaO, Na2 O, K2 O, MnO, TiO2, P2O5, and the main crystalline phase quartz, calcite, illite and seraphinite. HangJin clay is a kind of typical fine-grained soil, and it has a large specific surface area about 69.4m2/g. At the same time,the results of heavy metal leaching test also showed that the content of seven kinds of heavy metals including chromium, nickel, copper, zinc, arsenic, cadmium, lead is far below the national limited values, so Hangjin earth as a carrier material does not have the risk of leaching toxicity.And then nano zero valent iron and the different load ratios of nano zero valent iron supported on Hangjin clay were synthesized by using the liquid phase reduction method.By using the method of SEM, XRD, BET, nanoscale zero valent iron and nano-iron composite material were characterized. While its comparative analysis showed that the particles Fe0 successfully loaded onto Hangjin clay, which showed that Hangjin clay playing a good role in the dispersion and stabilization for nano zero valent iron.To further explore the applications of the prepared nanocomposite in water treatment, with the methyl orange dye and Hexavalent chromium for target pollutants,the effectiveness of influencing factors were experimentally made.Methyl orange as target pollutants, the initial concentration of 50mg/L methyl orange simulated wastewater, under the condition of the optimal dosage of the H-nZVI 3.0g/L, the optimal load ratio 1: 3, and the room temperature of 25 ℃, pH = 3.0, H-nZVI removal rate of methyl orange were 97.77% within 10 min.The results indicated that the material has a good decolorization of methyl orange. Meanwhile, the degradation of methyl orange by H-nZVI follows the first-order reaction kinetics.Hexavalent chromium as target pollutants, the initial concentration of 10mg/L of chromium contained in wastewater, under the conditions of the best dosage of H-nZVI 2.0g / L, the optimal load ratio of 1: 2, and the room temperature of 25℃, pH = 6.70. The removal rate of Hexavalent chromium reached 99.68% within 20 min. As a result, the composite material has a good effect on the removal of the Hexavalent chromium.