The Study On The Simultaneous Remediation Of Contaminated Groundwater By Zero-valent Iron And The Simulation Of Appraisal And The Prediction

Zero valent iron is a powerfull reductive agent that can remove the groundwater contaminant.The preparation processes of common Pd/ Fe bimetal, nanoscale Fe and Ni/ Fe bimetal were discussed in this thesis. By making use of TEM, BET-N₂ and XRD etc we measured the shade, sizes and ratio area of reduction iron powder, common Pd/Fe and nanoscale Pd/Fe. Meanwhile, the crystal structures of nanoscale Fe and nanoscale Pd/Fe were also investigated. The regular patterns of concentration of reactant and product in reaction processes were studied by using the following methods and techniques: the Cr(VI) wiping off research using both reduction iron powder and nanoscale Fe, the p-NCB catalysis reduction dechloration research using common Pd/Fe bimetal and nanoscale Ni/Fe bimetal, and the synchronous restoration research of Cr(VI) and p-NCB using nanoscale Ni/Fe bimetal. The influences of many factors such as various catalytic reduction agent, palladium rate, adding dose of nanoscale Pd/Fe, reaction temperature, initial pH values and initial reactant concentration on the disposal effect and reaction rates were investigated. The Cr(VI) wiping off mechanism was studied by analyzing the Oxidation-Reduction Reactions potential analysis based on the E-pH diagram, and the mechanism of p-NCB catalysis reduction dechloration was suggested via the analysis of intermediates and products. In combination of the in situ groundwater treatment pilot plant data with the base experiment data we established a prediction model for the ZVI groundwater restoration. The experimental results are given as follows:1. The TEM analysis indicates that the surface pure Fe is smooth and even, while the surface pure common Pd/Fe exhibits many small white protuberances, which form the surface catalyzed active bits. It is shown that the diameter of most nanoscale Fe and Ni/Fe is less than 100 nms, and that the catalyst granules conjunct each other and exhibit the branch-shape structure. The BET-N₂ measurement shows that the ratio surface area of the iron powder, Pd/Fe iron (0.005%) and nanoscale Fe are 0.49, 0.62 and 12.4 m²/g respectively. It is demonstrated that the 110 diffraction peak of Fe (d=0.2027 nm) appears in the XRD diagram of nanoscale Fe and common Pd/Fe. However, there exists no Pd diffraction peaks in the XRD diagram of common Pd/Fe.2. The possible factors, which have influence on the Fe wiping off Cr(VI) reaction rate, are as follows: Fe adding dose, Cr(VI) beginning concentration ,the reaction temperature, the initial pH value, humic acid concentration, copper ion concentration, starch adding dose and so on. Our experiments indicate that the larger Fe adding dose, the higher reaction temperature with the lower initial pH value has positive effect on the Cr(VI) wiping off reaction. The appropriate humic acid concentration, copper ion concentration and starch adding dose can lead to the rapid reaction rate in the Cr(VI) wiping off reaction. In general, the apparent dynamical constants of Cr(VI) wiping off is linear functions of both the Fe adding dose and the...