壳聚糖-纳米铁去除上覆水和底泥中Cr(Ⅵ)、Pb^(2+)、Cd^(2+)的研究

Removing Cr(Ⅵ),Pb^(2+) and Cd^(2+) from overlying water and sediment by nanoscale zero-valent iron entrapped in chitosan beads

利用具有较好抗氧化性和分散性的壳聚糖-纳米铁(CS-NZVI)颗粒去除上覆水-底泥系统中的Cr(Ⅵ)、Pb^(2+)、Cd^(2+),分析了Cr(Ⅵ)、Pb^(2+)、Cd^(2+)去除的动力学特征,考察了pH和盐度对去除效果的影响。结果表明,CS-NZVI颗粒能够有效去除上覆水及底泥中的Cr(Ⅵ)、Pb^(2+)、Cd^(2+),Cr(Ⅵ)、Pb^(2+)、Cd^(2+)的去除过程满足准一级反应动力学方程;随着pH的升高,上覆水中Cr(Ⅵ)的去除率逐渐降低,而Pb^(2+)、Cd^(2+)去除率逐渐升高,底泥中Cr(Ⅵ)去除率先大幅降低后小幅上升,而Cd^(2+)、Pb^(2+)去除率总体呈降低趋势;高盐度不利于上覆水中Cr(Ⅵ)的去除,但对底泥中Cd^(2+)和Pb^(2+)的去除具有促进作用,对底泥中Cr(Ⅵ)的去除没有明显影响。

Nanoscale zero-valent iron supported chitosan（CS-NZVI）was successfully prepared which had good oxidation resistance and dispersion.The obtained CS-NZVI beads was used to remove Cr（Ⅵ）,Pb2＋and Cd2＋from the polluted overlying water and sediment.The kinetics of Cr（Ⅵ）,Pb2＋and Cd2＋removal was investigated,and the effect of pH and salinity on Cr（Ⅵ）,Pb2＋and Cd2＋removal was also demonstrated.Results showed that Cr（Ⅵ）,Cd2＋and Pb2＋in the overlying water and sediments could be effectively removed by CS-NZVI beads.Kinetics of Cr（Ⅵ）,Pb2＋and Cd2＋removal was found to follow the pseudo-first-order rate equation.With the increasing of pH,the removal rate of Cr（Ⅵ）in overlying water gradually reduced,while the removal rate of Pb2＋and Cd2＋was increased,the Cr（Ⅵ）removal rate of sediment was significantly reduced at first and then increased a little,while the Cd2＋and Pb2＋removal rate of sediment was overall decreased.High salinity was not conducive to Cr（Ⅵ）removal from overlying water,but it had a promoting effect on Cd2＋and Pb2＋removal from sediments,while its effect on Cr（Ⅵ）removal from sediments was not obvious.