δ-MnO2/沸石纳米复合材料同时去除地下水中的铁锰氨氮

Removal of Fe（Ⅱ）,Mn（Ⅱ）,and NH4+-N by Using δ-MnO2 Coated Zeolite

以天然沸石颗粒、高锰酸钾、硫酸锰为原料,通过常温氧化还原沉淀法制备δ-MnO2/沸石纳米复合材料,用于同时去除地下水中铁锰氨氮.扫描电镜(SEM)、透射电镜(TEM)、Zeta电位、红外光谱(FTIR)和X射线光电子能谱(XPS)表征负载锰氧化物和吸附离子的存在形态,探讨δ-MnO2/沸石对Fe2+、Mn2+和NH4+-N的吸附机制.通过静态无/低氧水处理实验研究了δ-MnO2/沸石对Fe2+、Mn2+和NH4+-N的吸附性能.结果表明,沸石表面负载的锰氧化物为δ-MnO2;复合材料对3种离子的吸附符合准二级动力学,吸附等温曲线符合Langmuir模型,最大饱和吸附容量可分别达到215. 1、23. 6和7. 64mg·g-1;水中氨氮去除机制是沸石对NH4+的优先选择性离子交换吸附;水中Fe2+和Mn2+的去除是沸石颗粒表面负载δ-MnO2的吸附和催化氧化作用.研究表明δ-MnO2/沸石纳米复合材料可以作为一种高效吸附剂同时去除水中的Fe2+、Mn2+和NH4+-N离子.

MnO2/zeolite nanocomposites were prepared with natural zeolite,potassium permanganate,and manganese sulfate by oxidation-reduction precipitation,which were used to simultaneously remove Fe2+,Mn2+,and NH4+-N from groundwater.To investigate the performance and mechanism of Fe2+,Mn2+,and NH4+-N removal from groundwater byδ-MnO2/zeolite nanocomposites,static batch experiments were conducted under different environmental conditions in a zero-oxygen atmosphere using SEM,TEM,Zeta potential,FTIR,and XPS techniques.The experimental results showed that the manganese-oxide-coated natural zeolite wasδ-MnO2,and Fe2+,Mn2+,and NH4+-N adsorption on theδ-MnO2/zeolite nanocomposites could be best described with the pseudo-second-order kinetic model and the Langmuir model.In addition,the maximum adsorption capacities of Fe2+,Mn2+,and NH4+-N were calculated to be 215.1,23.6,and 7.64 mg·g-1,respectively.The removal mechanism of NH4+-N from the solutions by zeolite was via the action of ion exchange,and the adsorption and oxidation catalysis ofδ-MnO2-coated zeolite were responsible for the removal of Fe2+and Mn2+.This research indicates thatδ-MnO2/zeolite nanocomposites could be used as highly efficient adsorbents to simultaneously remove Fe2+,Mn2+,and NH4+-N from water.