Zhang Qian, Ji Fangying, Jiang Lei, Shen Qiushi, Mao Yuanxiang, Liu Caocong
College of Environment and Ecology, Chongqing University, Chongqing 400045, China.
Nanomaterials (Basel). 2022 Feb 9;12(4):586. doi: 10.3390/nano12040586.
Phosphate is the main cause of eutrophication. Layered double hydroxides (LDH) are considered to be promising phosphate adsorbents due to their high affinity and large capacity. In this study, we partially intercalated zwitterionic glycine and alanine into Cl-LDH (corresponding to MgAl-LDH with interlayer anion Cl) and synthesized efficient inorganic-organic nanohybrids for phosphate removal with kinetic advantages. Gly-Cl-LDH, Ala-Cl-LDH and Cl-LDH were characterized, and their phosphate adsorption performances under the influence of environment factors (e.g., solution pH, coexisting anions, contact time and phosphate concentration) were investigated. The results show that Gly-Cl-LDH and Ala-Cl-LDH had larger specific surface areas and larger interlayer spaces than Cl-LDH, and exhibited better adsorption performance at a lower pH and better adsorption selectivity against SO. Kinetic experiments indicated that Gly-Cl-LDH and Ala-Cl-LDH can reduce phosphate concentrations to a lower level in a shorter time. The pseudo-second-order kinetic constants of Gly-Cl-LDH and Ala-Cl-LDH were 1.27 times and 3.17 times of Cl-LDH, respectively (R > 0.996). The maximum adsorption capacities derived from a Langmuir model of Cl-LDH, Gly-Cl-LDH and Ala-Cl-LDH are 63.2 mg-P/L, 55.8 mg-P/L and 58.2 mg-P/L, respectively, which showed superiority over the prevailing phosphate adsorbents. This research provides highly efficient adsorbents for removing phosphate from aqueous solutions.
磷酸盐是富营养化的主要原因。层状双氢氧化物（LDH）因其高亲和力和大容量而被认为是很有前景的磷酸盐吸附剂。在本研究中，我们将两性离子甘氨酸和丙氨酸部分插层到Cl-LDH（对应于层间阴离子为Cl的MgAl-LDH）中，合成了具有动力学优势的用于去除磷酸盐的高效无机-有机纳米杂化物。对Gly-Cl-LDH、Ala-Cl-LDH和Cl-LDH进行了表征，并研究了它们在环境因素（如溶液pH值、共存阴离子、接触时间和磷酸盐浓度）影响下的磷酸盐吸附性能。结果表明，Gly-Cl-LDH和Ala-Cl-LDH比Cl-LDH具有更大的比表面积和更大的层间间距，并且在较低pH值下表现出更好的吸附性能以及对SO更好的吸附选择性。动力学实验表明，Gly-Cl-LDH和Ala-Cl-LDH能够在更短的时间内将磷酸盐浓度降低到更低水平。Gly-Cl-LDH和Ala-Cl-LDH的准二级动力学常数分别是Cl-LDH的1.27倍和3.17倍（R>0.996）。由Langmuir模型得出的Cl-LDH、Gly-Cl-LDH和Ala-Cl-LDH的最大吸附容量分别为63.2 mg-P/L、55.8 mg-P/L和58.2 mg-P/L，这显示出优于现有磷酸盐吸附剂的性能。本研究为从水溶液中去除磷酸盐提供了高效吸附剂。
