不同锌铝比水滑石的合成及其吸附脱除水中邻苯二甲酸性能

Zn/Al Hydrotalcite with Different n_(Zn)/n_(Al) Molar Ratios:Synthesis and Phthalic Acid Adsorption Behaviour

采用共沉淀法合成一系列具有不同锌铝比的水滑石,并利用X射线衍射(XRD)、扫描电镜(SEM)、热重(TG)、氮气吸脱附及电感耦合等离子体质谱(ICP-MS)等表征手段对其结构与组成进行了测试。将上述水滑石材料用于吸附脱除水中邻苯二甲酸污染物,考察了不同锌铝比水滑石吸附邻苯二甲酸性能的差异。结果表明,在较低锌铝比时,随着水滑石锌铝比的增加,其对邻苯二甲酸的吸附量逐渐增大;当锌铝比较大时(>6),随着锌铝比的增加,水滑石的吸附量基本保持不变。进一步选取锌铝比为6的水滑石,分别对其吸附邻苯二甲酸的动力学和热力学进行了研究,发现其吸附等温线和吸附动力学数据分别符合Freundlich等温吸附模型和准二级动力学模型,且循环吸附性能较好。

Zn-Al layered double hydroxides （LDHs） with different Zn/Al molar ratios were prepare by co-preci-pitation method in this work. The structure and composition were investigated using X-ray diffraction （XRD）, scanning electron microscope （SEM）, thermogravimetric （TG）, N2 adsorption-desorption and inductively coupled plasma mass spectrometry （ICP-MS）. The adsorption properties of as-prepared Zn/Al hydrotalcites for phthalic acid removal from water were investigated and compared. Results show that the adsorption capacity increased with the increasing of Zn/Al molar ratios at low Zn/Al molar ratios for hydrotalcites. Further increasing the nZn/nAl molar ratios （〉6）, the adsorption capacity shows little change. Among those hydrotalcites, one sample with the highest adsorption capacity was selected and its adsorption kinetic and isotherm was further investigated. The adsorption equilibrium data were well described by Freundlich isotherm model and the kinetics followed a pseudo-second order kinetic equation/mechanism. In addition, the hydrotalcite can be reused at least 3 cycles without significant loss of adsorption capacity.