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化学学报
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化学学报 ›› 2012, Vol. 70 ›› Issue (17): 1798-1804.DOI: 10.6023/A12040115 上一篇    下一篇

研究论文

酸性湖蓝7在LDO上吸附性能及机理的研究

祝海涛, 倪哲明, 薛继龙   

  1. 浙江工业大学化学工程与材料科学学院 杭州 310014
  • 投稿日期:2012-04-14 发布日期:2012-07-19
  • 通讯作者: 倪哲明
  • 基金资助:
    项目受浙江省自然科学基金(No. Y406609)资助.

Adsorption Applications of Acid Blue 7 on Mg/Al Layered Double Oxides and Mechanism Study

Zhu Haitao, Ni Zheming, Xue Jilong   

  1. College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310014
  • Received:2012-04-14 Published:2012-07-19
  • Supported by:
    Project supported by the Natural Science Foundation of Zhejiang Province (No. Y406609).

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1359

被引次数

15

探讨了Mg/Al＝3的水滑石焙烧产物(MgAl-LDO)对染料酸性湖蓝7(AB7)的吸附性能及其机理. 考察了不同因素对MgAl-LDO吸附AB7性能的影响, 并研究了吸附过程的热力学机理. 实验结果表明: MgAl-LDO对AB7具有优异的吸附性能, 在288 K, pH＝6.74条件下, 0.33 g·L-1 MgAl-LDO对150 mg·L-1AB7溶液的吸附容量和去除率分别达到446.9 mg·g-1和99.31%. 热力学研究表明: MgAl-LDO对AB7的吸附过程同时符合Langmuir 和 Freundlich等温吸附方程, 并且是个放热、自发的过程. 计算所得的吉布斯自由能绝对值在8～10 kJ·mol-1, 这主要是由染料分子与水滑石层板的氢键作用产生, 结合Materials Studio 5.5软件模拟AB7染料分子在MgAl-LDHs上的排列分布, 推测MgAl-LDO对AB7的吸附机理是表面吸附作用. 同时, 经4次回收, LDO对AB7的去除率仍达到85%以上.

关键词: 镁铝二元水滑石焙烧产物, 吸附, 机理, 酸性湖蓝7

Layered double hydroxides (LDHs) have received considerable attentions in recent years owing to their unique layered structures. Their general formula is [M1-x2+Mx3+(OH)2](An-)x/n·mH2O, where M is metal cation and A is an exchangeable anion. LDHs are layered materials with hydroxide sheets, where a net positive charge is developed on the layer due to partial substitution of trivalent for divalent cations, balanced by exchangeable charge compensating anions and water molecules, that are present in the interlayer space. The adsorption property and mechanism of Acid Blue 7 (AB7) on MgAl Layered double oxides with 3∶1 Mg/Al molar ratio were investigated. The adsorption of AB7 on MgAl-LDO was carried out using the batch method. We changed the dosage of adsorbent, pH value and initial dye concentration to study the influences of various factors and then calculated the maximum capacity of AB7 adsorbed at equilibrium (Qe) and percentage of adsorption (η%) respectively. The results of adsorption experiments indicated that the maximum capacity of AB7 at equilibrium (Qe) and percentage of adsorption (η%) with a fixed adsorbent dose of 0.33 g·L-1 were found to be 446.9 mg·g-1 and 99.31%, when AB7 concentration, temperature, and pH were 150 mg·L-1, 288 K and 6.74, respectively. Adsorption isotherms showed that the adsorption process was consistent with both Langmuir and Freundlich equations. It was also spontaneous and exothermic. The Gibbs free energy was calculated to be 8 to 10 kJ·mol-1 because of hydrogen bonds between the layers and dye molecular. According to the calculation of Materials Studio5.5, a periodical model of MgAl-LDHs was established in hexagonal (2H) stacking sequence, containing MgAl-OH as host layer and CO32- as guest anion, that is the host-guest interaction model with in the position of hcp-Al. The mechanism of adsorption process was that the majority of AB7 were adsorbed on the surface of MgAl-LDO. The regeneration for re-use of LDO after AB7 sorption was feasible with four cycles.

Key words: calcined Mg/Al layered double hydroxides (MgAl-LDO), adsorption, mechanism, Acid Blue 7