零价纳米铁对水中Cr(VI)的吸附动力学研究

Kinetics of Cr(VI)Removal from Aqueous Solution with Nanoscale Zero-Valent Iron

为开发新型环境材料,改进治理技术以控制或修复污染水体中Cr(Ⅵ),采用NaBH4还原Fe3+制备纳米级零价铁(NZVI)。X射线衍射(XRD)及扫描电镜(SEM)测试表明,制备的纳米铁颗粒纯度高、粒径小、粒度均匀。以Cr(VI)为研究对象,批试验考查了溶液初始浓度、NZVI投加量、温度等条件对去除效果的影响,研究了NZVI对Cr(VI)的吸附动力学。结果表明,室温、pH值为6—7时,NZVI加入量为0.15g/L,水体中Cr(VI)浓度为30.0mg/L时,Cr(VI)最大吸附量为198.02mg/g,Cr(VI)在NZVI上的吸附符合准二级动力学方程。实验结果显示,纳米零价铁能快速去除水体中Cr(VI);溶液初始浓度、NZVI投加量等是影响Cr(VI)脱除的主要因素,Cr(VI)去除率随反应温度和NZVI投加量升高而升高,随初始浓度升高而降低。实验表明,该纳米铁在废水除铬领域具有较好的应用前景。

A new type of environmental materials,the Nanoscale Zero-Valent Iron（NZVI）,was synthesized in aqueous solutions by reduction of Fe3＋with NaBH4 in order to develop a new technology to control or remediate the polluted water containing Cr（VI）.The characterization with X-Ray Diffraction（XRD）and Scanning Electron Microscopy（SEM）indicates that the prepared NZVI particles are uniform in distribution and small in diameter with high purity.In the batch removal of Cr（VI）from simulated wastewater,the influences of initial Cr（VI）concentration,temperature and NZVI loading on Cr（VI）reduction on the surface of the NZVI are studied.It is found that each gram of NZVI could remove 198.02 mg of Cr（VI）from the simulated wastewater containing 30.0mg/L of Cr（VI）with an initial pH of 6—7 at room temperature.The kinetics of the Cr（VI）removal is found to follow the pseudo-second-order rate equation.The study reveals that Cr（VI）can be efficiently removed by means of absorption of NZVI in the solution and the key to achieving a high removal rate lies in the appropiate handling of factors involving initial concentration of Cr（VI）and iron loading.The reduction rates are increased with the increase of temperature and iron loading but decreased with the increase of initial Cr（VI）concentration.The experimental data show that the NZVI is very attractive for the removal of Cr（VI）from wastewater.