| 应用纳米零价铁处理模拟含Cr(Ⅵ)无氧地下水 |
| 摘要点击 8305 全文点击 3597 投稿时间：2009-05-14 修订日期：2009-08-14 |
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| 中文关键词 纳米零价铁 Cr(Ⅵ) 地下水 动力学 机制 |
| 英文关键词 nanoscale zero-valent iron(Fe) Cr(Ⅵ) ground water kinetics mechanism |
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| 中文摘要 |
| 研究了实验室自制的纳米零价铁处理模拟含Cr(Ⅵ)无氧地下水的影响因素、吸附动力学，并结合体系中Fe2+浓度、氧化还原电位、Zeta电位和理论计算得到的pe-pH图对纳米零价铁去除Cr(Ⅵ)的机制进行了探讨.实验结果表明，纳米零价铁对Cr(Ⅵ)的去除率随着初始Cr(Ⅵ)/Fe质量比的升高而降低.当溶液的pH为7.0，初始Cr(Ⅵ)/Fe质量比为0.025、0.050、0.075和0.100时，相应地Cr(Ⅵ)的去除率分别为100.0%、85.6%、72.7%和39.6%.酸性条件更有利于纳米零价铁对Cr(Ⅵ)的去除，当初始Cr(Ⅵ)/Fe质量比为0.100，溶液的pH为3.0、5.0、7.0、9.0和11.0时，体系中Cr(Ⅵ)的去除率分别为73.4%、57.6%、39.6%、44.1%和41.2%.纳米零价铁去除Cr(Ⅵ)的过程符合拟二级动力学方程.当溶液的pH为7.0，初始Cr(Ⅵ)/Fe质量比为0.025时，吸附速率常数(k)最大，为9.76×10-3g·(mg·min)-1.Cr2O2-7 吸附到纳米零价铁表面后被迅速地还原为Cr3+，生成的Cr3+ 与纳米零价铁表面的FeOOH结合生成Cr-Fe膜.而Cr-Fe膜将阻断电子在纳米零价铁与Cr2O2-7之间的传输，Cr(Ⅵ)得不到还原，从而纳米零价铁对Cr2O2-7的去除以吸附为主. |
| 英文摘要 |
| Laboratory experiments and theoretical modeling studies were performed to investigate the mechanisms of Cr(Ⅵ) removal from deoxygenated simulated groundwater using nanoscale zero-valent iron,and to evaluate influencing factors and kinetics based on zeta potential,redox potential,ferrous concentrations,and the pe-pH diagram of Fe-Cr-H2O system. Experimental results demonstrate that the removal efficiency of Cr(Ⅵ) decreases with the increasing Cr(Ⅵ)/Fe mass ratio. When the Cr(Ⅵ)/Fe mass ratios are 0.025,0.050,0.075,and 0.100,the corresponding Cr(Ⅵ) removal rates are 100.0%,85.6%,72.7% and 39.6%,respectively. The Cr(Ⅵ) removal is favorable at acidic pH with fixed Cr(Ⅵ)/Fe mass ratio of 0.100. When pH are 3.0，5.0，7.0，9.0 and 11.0,the Cr(Ⅵ) removal rates are 73.4%，57.6%，39.6%，44.1%,and 41.2%,accordingly. The Cr(Ⅵ) removal follows the pseudo second-order kinetics. When pH is 7.0 and Cr(Ⅵ)/nZVI mass ratio is 0.025,the rate of Cr(Ⅵ) removal is the highest with rate constant at 9.76×10-3g·(mg·min)-1. The conversion from Cr2O2-7 to Cr3+ should be instantaneous when Cr2O2-7 is absorbed on the surface of Fe. The Cr(Ⅵ) was reduced to Cr(Ⅲ),which was subsequently incorporated into the FeOOH shell and formed a Cr-Fe film. The film once formed could further inhibit the electron transfer between Cr2O2-7 and Fe. Then Cr(V) removal was primary controlled by the adsorption process. |
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