无机化学学报

镁铝双金属氢氧化物及氧化物去除硫离子(S^2-)性能及其机理研究

Performance and Mechanism of Mg, Al Layered Double Hydroxides and Layered Duble Oxides for Sulfide Anion (S^2-) Removal

作者	单位
刘淼	北京化工大学化工资源有效利用国家重点实验室，北京 100029
杨俊佼	北京化工大学化工资源有效利用国家重点实验室，北京 100029
武国庆	北京化工大学化工资源有效利用国家重点实验室，北京 100029
王连英	北京化工大学化工资源有效利用国家重点实验室，北京 100029

摘要: 利用层状双金属氢氧化物(LDHs)层间阴离子的可交换性及其结构记忆效应，研究了氯离子插层镁铝双金属氢氧化物(MgAl-Cl-LDHs)及镁铝双金属氧化物(MgAl-LDO)去除S^2-的性能及机理。采用X射线粉末衍射(XRD)、红外光谱(FTIR)、紫外-可见光谱(UV-Vis)和电感耦合等离子体原子发射光谱(ICP)等表征技术，详细探讨了焙烧复原法及离子交换法得到的不同产物的结构和去除S^2-性能，提出了MgAl-Cl-LDHs和MgAl-LDO对S^2-的不同去除机理。结果表明，MgAl-LDO具有较MgAl-Cl-LDHs更为优良的去除S^2-性能。文中所有去除实验的pH值均为9，此时S^2-发生水解且主要以HS-存在于溶液中。采用MgAl-Cl-LDHs为前体时，HS^-的离子交换能力比Cl^-弱，不能通过与Cl^-交换进入层间，S^2-的去除机理主要是表面吸附HS^-及将其氧化成S₂O₃^2-。以MgAl-LDO为前体时，HS^-通过LDO结构恢复能迅速进入层间，且受MgAl-LDO的催化氧化性能的影响，在结构恢复的同时HS-被氧化成S₂O₃^2-、S^2-和S^3-，可以高效去除溶液中的S^2-。n_Mg/n_Al比为2的LDHs在500 ℃下焙烧的产物MgAl-LDO对S^2-的去除率能够达到98%以上，以MgAl-LDO去除S^2-的方法可作为一种高效除S^2-的方法。

关键词: 层状双金属氢氧化物硫离子结构记忆效应去除性能去除机理

基金项目:

Abstract: Based on the exchangeable property of the interlayer anions and the so-called “memory effect” of the layered double hydroxides (LDHs), the capacities and mechanisms for sulfide anion (S^2-) removal were studied using chloride-containing MgAl-LDHs (MgAl-Cl-LDHs) and the layered double oxides (MgAl-LDO). Structures of the products obtained by anion exchange and reconstruction, and the removal capacities were characterized by XRD, FTIR, UV-Vis and ICP, and the different mechanisms for MgAl-Cl-LDHs and MgAl-LDO were proposed. The results indicate that the removal capacity for MgAl-LDO is much greater than that for MgAl-Cl-LDHs. In this work S^2- removal test was proceed at pH of 9, and then S^2- was hydrolyzed, and mainly existed as HS^- in the solution. When MgAl-Cl-LDHs was used as the precursor to remove S^2-, due to the weaker exchange capacity for HS^- compared to Cl^-, HS^- could not enter the interlayer through anion exchange with Cl^-. Adsorption of HS^- to the sample′s surface and oxidation to S₂O₃^2- are the removal mechanism for MgAl-Cl-LDHs. While when MgAl-LDO was used as the precursor, during the structure recovering, HS^- entered the interlayer qickly, and was oxidized to thiosulfate anion (S₂O₃^2-) and polysulfide anions (S^2- and S^3-) simultaneously. Therefore, MgAl-LDO can remove S^2- efficiently. The products of LDHs with Mg/Al molar ratio of 2 calcined at 500 ℃ were shown to have a high degree of removal capacity at above 98%.

Keywords: layered double hydroxides (LDHs) sulfide anion memory effect removal capacity removal mechanism

摘要点击次数: 1366

全文下载次数: 1839

刘淼,杨俊佼,武国庆,王连英.镁铝双金属氢氧化物及氧化物去除硫离子(S^2-)性能及其机理研究[J].无机化学学报,2006,22(10):1771-1777.

查看全文查看/发表评论下载PDF阅读器

Support information: