Superb adsorption of organic dyes from aqueous solution on hierarchically porous composites constructed by ZnAl-LDH/Al(OH)3 nanosheets
Superb adsorption of organic dyes from aqueous solution on hierarchically porous composites constructed by ZnAl-LDH/Al(OH)3 nanosheets
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ZnAl-LDH/Al(OH)3 纳米片构建的分级多孔复合材料对水溶液中的有机染料具有出色的吸附作用
DOI：
10.1016/j.micromeso.2017.10.003
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发表时间：
2018-03-15
影响因子：
5.2
通讯作者：
Yang, Hui
中科院分区：
文献类型：
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作者：
Guo, Xingzhong;Yin, Pengan;Yang, Hui
采用溶胶-凝胶法制备了ZnAl-Cl型层状双氢氧化物（LDH）纳米片和无定形Al（OH）（3）纳米片构成的多级多孔复合材料，并将其用于吸附水中的两种典型阴离子染料甲基橙子（MO）和刚果红（CR）。研究了ZnAl-LDH/Al（OH）（3）复合材料煅烧前后的微观结构和吸附性能。并对吸附机理和吸附-脱附循环进行了讨论。材料表征表明，复合材料具有三维宏观结构，大孔相互连通，骨架由ZnAl-LDH和Al（OH）（3）纳米片构成。在500 ° C下煅烧允许从LDH复合物转变为层状双金属氧化物（LDO），同时宏观结构基本上保持为具有0.5 μ m的大孔尺寸、53.1%的孔隙率和高达122 m2/g的BET表面积。吸附性能表明，多级多孔复合材料对阴离子染料CR和MO具有超快的吸附速率和较高的吸附容量。通过在500 ℃煅烧，分级多孔LDH基复合材料和LDO复合材料的最大吸附容量分别为2348.3和1574.4 mg g（-1）的CR和1013.5和1015.1 mg g（-1）的MO。吸附后的XRD和FTIR结果表明，MO和CR-阴离子通过与原始氯离子基团的离子交换嵌入LDH结构中，并附着在Al（OH）（3）表面上，从而导致层间空间的扩展。煅烧产物在染料水溶液中通过重构过程可逆地转变回LDH结构。吸附-脱附循环表明，所制备的多级多孔复合材料具有良好的可回收性，循环5次后，对CR和MO的去除率分别为80.2%和73.7%。
Hierarchically porous composites constructed by ZnAl-Cl type layered double hydroxides (LDH) nanosheets and amorphous Al(OH)(3) nanosheets were synthesized via a facile sol-gel route for the adsorption of two typical anionic dyes Methyl Orange (MO) and Congo Red (CR) from aqueous solutions. The micro-macrostructure and adsorption properties of hierarchically porous ZnAI-LDH/Al(OH)(3) composites before and after calcination were investigated in detail. The adsorption mechanism and adsorption-desorption cycles were also discussed. Materials characterization confirm that the resultant hierarchically porous composites possess three-dimensional macrostructure with interconnected macropores and co-continuous skeletons constructed by ZnAl-LDH and Al (OH)(3) nanosheets. Calcination at 500 degrees C allows the transformation from LDH composite to layered double metal oxides (LDO), while the macrostructure is basically maintained with a macropore size of 0.5 pm, a porosity of 53.1% and a BET surface area as high as 122 m(2) g(-1). Adsorption performances show that hierarchically porous composites exhibit ultrafast adsorption rates and high adsorption capacities in the removal of anionic dyes CR and MO. The maximum adsorption capacities of hierarchically porous LDH-based composites and LDO composites via calcination at 500 degrees C are 2348.3 and 1574.4 mg g(-1) for CR and 1013.5 and 1015.1 mg g(-1) for MO, respectively. XRD and FTIR results after the dyes adsorption indicate that the intercalation of MO and CR-anions into the LDH structure via ion exchange with the pristine chloride ions group and the attachment on the external Al(OH)(3) surface determine the adsorption behavior, thus leading to an expansion of the interlayer space. And the calcined products LDO-based composites can be reversibly transformed back into the LDH structure via reconstruction procedure in the presence of dyes aqueous solution. Furthermore, the adsorption-desorption cycles confirm that the as-prepared hierarchically porous composites own excellent recyclable properties and the removal efficiency for CR and MO are 80.2% and 73.7% even after five cycles, respectively.