钙铝和铁铝水滑石的制备及其吸附水中六价铬的性能

Preparation of CaAl-and FeAl-layered double hydroxides and adsorptive removal Cr(Ⅵ)in aqueous solutions

为寻找高效吸附水中六价铬(Cr(Ⅵ))的水滑石功能材料,以水热法制备钙铝(CaAl-LDH)和铁铝水滑石(FeAlLDH)2种吸附剂,通过X射线衍射仪、红外光谱仪、扫描电镜和比表面积测定仪研究其结构和性质,采用批次平衡实验比较研究其对水中Cr(Ⅵ)的吸附性能。结果表明:CaAl-LDH和FeAl-LDH具有水滑石的特征衍射峰和介孔结构,呈六边形片状,比表面积分别为8.746、159.5 m^(2)/g;2种材料对Cr(Ⅵ)的吸附速率较快,在30 min达到平衡,且吸附过程不受溶液pH值的影响,溶液中存在的常见阴离子对Cr(Ⅵ)影响较小;吸附动力学和等温线数据分别符合拟二级动力学方程和Langmuir等温线模型,CaAl-LDH和FeAl-LDH对Cr(Ⅵ)的最大吸附量分别为34.92、51.31 g/kg。

To obtain layered double hydroxide(LDH)based functional materials for efficient removal hexavalent chromium(Cr(Ⅵ))from water,CaAl-LDH and FeAl-LDH were prepared by the hydrothermal method.The structure and property were investigated by X-ray diffraction pattern(XRD),Fourier transform infrared spectroscopy,scanning electron microscopy and specific surface area measurement.Batch equilibrium experiments were used to evaluate the adsorption performance of the as-prepared CaAl-LDH and FeAl-LDH for aqueous Cr(Ⅵ).The experimental results show that CaAl-LDH and FeAl-LDH have typical XRD peaks of LDH,mesoporous structure and hexagonal laminar shape.The specific surface areas are 8.746 and 159.5 m^(2)/g.The adsorption processes of Cr(Ⅵ)by CaAl-LDH and FeAl-LDH are fast and reache equilibrium within 30 min,andare not affected by the initial solution pH value and the common coexisting anions.The kinetic and isothermal data follow the pseudo-second-order kinetic equation and the Langmuir model,respectively.The maximum adsorption capacities of CaAl-LDH and FeAl-LDH for aqueous Cr(Ⅵ)are 34.92 and 51.31 g/kg.