Department of Chemistry, Shahid Bahonar University of Kerman, 76169-133 Kerman, Iran.
Department of Basic Sciences, Sari Agricultural Sciences and Natural Resources University, 4818168984 Sari, Iran.
J Colloid Interface Sci. 2017 Dec 15;508:65-74. doi: 10.1016/j.jcis.2017.07.101. Epub 2017 Jul 29.
Hexagonal mesoporous MgAl layered double hydroxide (LDH) was synthesized through a simple hydrothermal method and was employed without calcination as adsorbent in the removal of the direct anionic azo dye, Brilliant Yellow (BY). The adsorbent was characterized by XRD, FT-IR, SEM and BET surface area. Hexagonal platelets of MgAl LDH were fabricated with nanometric building blocks. Batch experiments were carried out for study effects of contact time, amount of adsorbent, solution pH and solution temperature on the removal efficiency of BY. The adsorption of BY onto the MgAl LDH was pH dependent and the highest value of adsorption capacity was observed at pH=6. The equilibrium adsorption data were obtained using the Langmuir, Freundlich and Temkin isotherms. The results indicated that the experimental adsorption data were fitted to Langmuir and Freundlich models. The maximum adsorption capacity of BY onto the MgAl LDH was found to be 115mg/g. The kinetic data of adsorption were evaluated by pseudo-first order and pseudo-second order, which described well by pseudo-second order model. The negative values of ΔG° at all temperature indicated that the adsorption process was spontaneous. The values of ΔH° and ΔS° were calculated 19.3kJ/mol and 80.5J/mol·K, respectively. The positive value of ΔH° shows that the adsorption was endothermic, while positive ΔS° value reflects increased disorder at the solid-solution interface during the adsorption.
通过简单的水热法合成了六方介孔 MgAl 层状双氢氧化物（LDH），并将其未经煅烧用作直接阴离子偶氮染料亮黄（BY）的吸附剂。通过 XRD、FT-IR、SEM 和 BET 表面积对吸附剂进行了表征。MgAl LDH 由纳米级构建块制成的六方片状物。进行了批实验，以研究接触时间、吸附剂用量、溶液 pH 和溶液温度对 BY 去除效率的影响。BY 在 MgAl LDH 上的吸附与 pH 有关，在 pH=6 时观察到吸附容量的最高值。使用 Langmuir、Freundlich 和 Temkin 等温线获得了平衡吸附数据。结果表明，实验吸附数据符合 Langmuir 和 Freundlich 模型。MgAl LDH 对 BY 的最大吸附容量为 115mg/g。吸附的动力学数据通过拟一级和拟二级进行评估，拟二级模型很好地描述了吸附过程。在所有温度下，ΔG°的负值表明吸附过程是自发的。ΔH°和ΔS°的值分别计算为 19.3kJ/mol 和 80.5J/mol·K。正值的 ΔH°表明吸附是吸热的，而正值的 ΔS°值反映了吸附过程中固-液界面上的无序增加。
