凹凸棒土负载纳米Fe/Ni的制备及其去除水中Zn(Ⅱ)性能研究

Preparation of nanoscale Fe/Ni@attapulgite composite and its adsoption property for Zn(Ⅱ)from aqueous solution

采用液相还原法制备以凹凸棒土为载体的纳米双金属Fe/Ni复合材料,通过Zn(Ⅱ)静态吸附试验,确定了除Zn(Ⅱ)效果最佳的Fe/Ni@ATP复合材料,即纳米铁与凹凸棒土的负载比为1∶2、Fe/Ni双金属中Ni掺杂比为2%,并考察了Zn(Ⅱ)初始浓度、pH及环境温度对该复合材料去除水中Zn(Ⅱ)效果的影响。结果表明,经过凹凸棒土负载和掺杂Ni改性以后,Fe/Ni@ATP复合材料的Zn(Ⅱ)去除率显著提高,颗粒团聚状况得到改善,比表面积明显增加。在实验条件范围内,较高的溶液pH值、环境温度以及较低的Zn(Ⅱ)初始浓度均有利于Fe/Ni@ATP复合材料对Zn(Ⅱ)的去除。该过程符合Langmuir吸附等温模型,吸附机理为零价铁表面氧化物与Zn(Ⅱ)的配合作用,此外,水中Zn(Ⅱ)也可以通过生成Zn(OH)_2沉淀的形式去除。

In this paper,a series of attapulgite absorbent-loaded nanoscale Fe/Ni bimetal(Fe/Ni@ATP)were synthesized by liquid phase reduction method.Through static adsorption test,the Fe/Ni@ATP composite showing the best removal efficiency of Zn(II)from aqueous solution was selected,with the loading ratio of nanoscale non-valent iron(nZVI)to attapulgite is 1∶2 and the Ni doping ratio in Fe/Ni bimetal is 2%.The effects of initial concentration of Zn(II),pH and ambient temperature on the removal rate of Zn(II)using the as-prepared composite were investigated.The results reveal that via means of attapulgite loading and Ni-doping modification,the removal efficiency of Zn(II)by Fe/Ni@ATP composite is significantly improved,along with the alleviation of particle aggolomeration phenomenon and the increase of specific surface area of the composite.Under the experimental conditions,relatively high solution pH and ambient temperature as well as low initial concentration of Zn(II)are beneficial to the removal of Zn(II)by Fe/Ni@ATP composite.This adsoption process fits well with the Langmuir adsorption isotherm model,indicating that the mechanism could be considered as the coordination reaction between Zn(II)and oxide on the surface of nZVI.In addition,the removal of Zn(II)from aqueous solution can also be attributed to the chemical precipitation of Zn(OH)2.