煅烧的水滑石同时去除水体中砷和氟

为探讨水滑石类材料对水体中氟、砷离子的同时去除效果,采用共沉淀法合成(Mg∶Al=2∶1)纳米类水滑石(LDHs),用傅立叶转换红外光谱、电子扫描透射电镜、X射线晶体衍射等手段对合成的材料进行了表征,并研究纳米材料在不同初始浓度、pH、吸附时间、阴离子干扰条件下其同时除砷氟性能。结果表明,煅烧后的水滑石(LDOs)对砷最大吸附量为51.02 mg/g,对氟最大吸附量为36.63 mg/g。吸附动力学实验表明,煅烧水滑石对砷的吸附在前6 h内基本完成,对氟的吸附在前10 h内基本完成。砷氟共存溶液保持pH=4~10及pH=6~8时,水滑石分别对砷、氟保持良好的吸附效率。对比不同阴离子对水滑石共除砷氟效率的影响,水滑石除砷速率受到阴离子影响力大小为:HPO2-4CO2-3NO-3Cl-SO2-4;水滑石除氟速率受到阴离子影响力大小为:CO2-3HPO2-4SO2-4Cl-NO-3。材料再生循环利用4次后,对砷和氟的吸附效率均能达到90%以上。实验结果表明,所合成的水滑石是一种优秀的能共除砷氟的吸附剂。

Removal of arsenate and fluoride in water by calcined layered double hydroxides

To study the removal of fluorine and arsenic simultaneously in aqueous solutions, layered double hydroxides (LDHs)(Mg:Al=2:1)was prepared by co-precipitation method, the product was characterized by infrared spectroscopy measurements, perspective electron microscopy scanning, X-ray diffraction(XRD),etc. The ability of LDHs to remove coexisting arsenic and fluoride from aqueous solution was investigated at different initial concentration of adsorbate, pH, reaction time and coexisting anions. The results show that the maximum adsorption values of arsenic and fluorine by calcined layered double hydroxides (LDOs) are 51.02 and 36.63 mg/g, respectively. In the dynamic experiment, the maximum adsorption for arsenic completed within 6 h, for fluorine within 10 h. The adsorption capacity for arsenic could be kept highly at pH 4~10, for fluorine at pH 6~8. The efficiency of different anions on the adsorption of arsenic and fluorine by LDOs was compared, for arsenic: HPO₄^2->CO₃^2->NO₃^->Cl^->SO₄^2-, and for fluorine: CO₃^2->HPO₄^2->SO₄^2->Cl^->NO₃^-. After four times of recycles, the removal rate of arsenic and fluorine is above 90%. The results prove that calcined LDHs is an effective adsorbent for coexisting arsenate and fluoride.