ABSTRACT

Recently, layered double hydroxides (LDHs) have been extensively researched for their anion exchange capabilities and exhibit a layered structure with a host layer of octahedrally coordinated metal cations and a guest layer (interlayer) of anions. In this study, we synthesized a CM-β-CD•Zn–Al LDH by anion exchange method to study the anionization of cyclodextrin (CD) to promote its incorporation into the LDH interlayers and its stability therein. Ni²⁺ adsorption by the CMCD•Zn–Al LDH by the anion exchange method was compared with the results co-precipitation method. The X-ray diffraction spectra of NO₃•Zn–Al LDH and CM-β-CD•Zn–Al LDH synthesized by the anion exchange method exhibit that the product peaks were attributable to $\mathrm{Z}{\mathrm{n}}_6\mathrm{A}{\mathrm{l}}_2{\left(\mathrm{O}\mathrm{H}\right)}_{16}\mathrm{C}{\mathrm{O}}_{3}4{\mathrm{H}}_2\mathrm{O}$ and possessed an LDH structure. Furthermore, all CM-β-CD•Zn–Al LDHs exhibited the presence of some CM-β-CD. The CM-β-CD•Zn–Al LDH was hypothesized to be composed of two types of layers: a CM-β-CD layer in which two molecules of CM-β-CD^7-, with cavity axes perpendicular to the LDH host layer, are vertically overlaid, and a NO₃-type Zn–Al LDH layer used as a precursor. CM-β-CD•Zn–Al LDH adsorbed Ni²⁺ in an aqueous solution. To determine whether Ni²⁺ adsorption by the CM-β-CD•Zn–Al LDH is driven chemically or physically, we fitted the data to the Freundlich and Langmuir adsorption models; the results showed that Ni²⁺ adsorption by the CM-β-CD•Zn–Al LDH is consistent with the Langmuir equation and could be considered a chemical adsorption.

摘要

近来，层状双氢氧化物（LDHs）已经对其阴离子交换能力进行了广泛的研究，并且显示出具有八面体配位金属阳离子的主体层和阴离子的客体层（中间层）的层状结构。在这项研究中，我们通过阴离子交换法合成了CM-β-CD•Zn-Al LDH，以研究环糊精（CD）的阴离子化，以促进其掺入LDH中间层及其稳定性。将CMCD•Zn-Al LDH阴离子交换法对Ni ^2+的吸附与结果共沉淀法进行了比较。阴离子交换法合成的NO ₃ •Zn-Al LDH和CM-β-CD•Zn-Al LDH的X射线衍射光谱表明，产物峰可归因于$\mathrm{ž}{\mathrm{ñ}}_6\mathrm{一种}{\mathrm{升}}_{\mathrm{2个}}{\left(\mathrm{Ø}\mathrm{H}\right)}_{16}\mathrm{C}{\mathrm{Ø}}_{3}4{\mathrm{H}}_{\mathrm{2个}}\mathrm{Ø}$并具有LDH结构。此外，所有CM-β-CD•Zn-Al LDH都显示出一些CM-β-CD的存在。的CM-β-CD•Zn-Al的LDH被假定可以由两种类型的层：其中的两个分子CM-β-CD在CM-β-CD层^{7 -}，与腔的轴线垂直于LDH主机层垂直覆盖，并使用NO ₃型Zn-Al LDH层作为前体。CM-β-CD•Zn-Al LDH在水溶液中吸附Ni ²⁺。为了确定CM-β-CD•Zn-Al LDH对Ni ^2+的吸附是化学驱动还是物理驱动，我们将数据拟合到Freundlich和Langmuir吸附模型中。结果表明，Ni ²⁺ CM-β-CD•Zn-Al LDH的吸附与Langmuir方程一致，可以认为是化学吸附。