热活化褐铁矿对水中三价砷的净化作用

Remove of trivalent arsenic in groundwater by thermally activated limonite

通过热活化褐铁矿制备以赤铁矿为主的纳米-微米多级孔结构颗粒材料,并用于模拟净化含As(Ⅲ)地下水。静态实验考察了热活化温度、溶液pH值、As(Ⅲ)浓度、反应温度以及吸附时间等因素对热活化褐铁矿去除水中As(Ⅲ)效果的影响,拟合计算反应动力学、热力学参数,并对反应后的固体产物进行表征分析,探究热活化褐铁矿去除水中As(Ⅲ)的机制。结果表明,300℃热活化产物赤铁矿的晶体粒径最小(2.7nm)、比表面积最大(107.4 m2/g)。当As(Ⅲ)初始浓度为1 mg/L时,pH值在2~7范围内对热活化褐铁矿去除As(Ⅲ)效果影响较小,去除率均在98%以上,反应遵循准二级动力学方程和Langmuir吸附等温模型。研究发现,热活化褐铁矿产物对As(Ⅲ)具有吸附和催化氧化作用,且矿物中的锰氧化物在As(Ⅲ)去除中具有显著的增强作用。因此,通过该方法制备的纳米矿物功能材料在地下水砷污染治理中具有很大的应用价值,同时为褐铁矿资源化利用提供新思路。

The nano-micron multi-level pore structural granular material with hematite as the main phase was obtained by thermally activating of limonite,and used to simulate the purification of As(Ⅲ)-containing groundwater.The effects of thermal activation temperature,solution pH,As(Ⅲ)concentration,reaction temperature,and adsorption time on the removal of As(Ⅲ)in water by thermally activated limonite were investigated in the static experiments,and the reaction kinetics and thermodynamic parameters were calculated.Characterizations of the solid product after the reaction were analyzed to explore the mechanism of As(Ⅲ)removal in water over the thermally activated limonite.The results showed that the hematite derived from the thermal activation of limonite at 300℃had the smallest crystal size(2.7 nm)and the largest specific surface area(107.4 m^2/g).When the initial concentration of As(Ⅲ)was 1 mg/L,slightly effect of the pH in the range of 2-7 on the removal of As(Ⅲ)by thermally activated limonite was observed,and the As(Ⅲ)removal were all above 98%.The reaction parameters indicated that the reaction followed the quasi-second-order kinetic equation and the Langmuir adsorption isotherm model.It was found that the thermally activated limonite possessed the adsorption and catalytic oxidation ability for As(Ⅲ)removal,and the manganese oxides in the material significantly enhanced the removal of As(Ⅲ).Therefore,this nano-mineral functional material prepared by thermally activating of limonite had great application potential for the treatment of the arsenic polluted groundwater,and provided a new idea for the utilization of limonite.