Adsorptive removal of phosphate by Mg–Al and Zn–Al layered double hydroxides: Kinetics, isotherms and mechanisms
Adsorptive removal of phosphate by Mg–Al and Zn–Al layered double hydroxides: Kinetics, isotherms and mechanisms
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DOI：
10.1016/j.seppur.2013.12.042
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发表时间：
2014-03
影响因子：
8.6
通讯作者：
Kun Yang;Liang-guo Yan;Yan-ming Yang;Shu-jun Yu;Ran-ran Shan;Haiqin Yu;Baocun Zhu;B. Du
中科院分区：
文献类型：
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作者：
Kun Yang;Liang-guo Yan;Yan-ming Yang;Shu-jun Yu;Ran-ran Shan;Haiqin Yu;Baocun Zhu;B. Du
磷酸盐的去除是天然水或废水处理的重要内容，吸附法是一种有效的处理方法。采用共沉淀法在pH为9 ~ 10的条件下合成了Mg-Al和Zn-Al层状双金属氢氧化物（LDHs）。采用X射线衍射（XRD）和BET比表面积测定等手段对所制备的水滑石进行了表征。XRD图谱显示了类水滑石LDH材料的特征基线反射。Zn-Al LDH的BET比表面积大于Mg-Al LDH。吸附实验进行了LDHs的用量，接触时间和磷酸盐溶液的初始pH值的函数。磷酸盐的吸附在40 min左右很快达到平衡。实验数据表明，符合准二级动力学模型。Freundlich和Langmuir模型均能较好地描述吸附等温线（R2> 0.98）。Zeta电位和傅立叶变换红外光谱（FTIR）分析用于阐明吸附机制。结果表明，磷酸盐在沸石上的吸附主要通过静电吸附、配体交换和离子交换三种方式进行。Zn-Al LDH对磷酸盐的去除率高于Mg-Al LDH，分别达到95%以上，表明Mg-Al和Zn-Al LDH对水溶液中的磷具有良好的吸附性能。
Phosphate removal is important for the natural water or wastewater treatment, and adsorption is an efficient treatment process. In this study, Mg–Al and Zn–Al layered double hydroxides (LDHs) were synthesized by co-precipitation method at a constant pH of 9–10. The prepared LDHs were characterized by X-ray diffraction (XRD) and BET surface area determination. The XRD patterns showed the characteristic basal reflections of hydrotalcite-like LDH materials. BET surface area of Zn–Al LDH was larger than that of Mg–Al LDH. Adsorption experiments were carried out as a function of LDHs dosage, contact time and initial pH of phosphate solution. The adsorption of phosphate reached equilibrium quickly at about 40 min. The experimental data showed a good compliance with the pseudo-second-order kinetic model. The Freundlich and Langmuir models both described the adsorption isotherm data well (R2> 0.98). Zeta potential and fourier transform infrared spectroscopy (FTIR) analyses were used to elucidate adsorption mechanisms. The results indicated that phosphate species were adsorbed via electrostatic attraction, ligand exchange and ion exchange. The removal ratio of phosphate onto Zn–Al LDH was higher than Mg–Al LDH and reached 95% respectively, suggesting that Mg–Al and Zn–Al LDHs were excellent adsorbents for phosphorus removal from aqueous solution.