Synthesis of Li鈥揂l Layered Double Hydroxides (LDHs) for Efficient Fluoride Removal
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- 作者：Tao Zhang ; Qiurong Li ; Haiyan Xiao ; Hongxiao Lu ; Yuming Zhou
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2012
- 出版时间：September 5, 2012
- 年：2012
- 卷：51
- 期：35
- 页码：11490-11498
- 全文大小：456K
- 年卷期：v.51,no.35(September 5, 2012)
- ISSN：1520-5045
文摘
A novel adsorbent of Li鈥揂l layered double hydroxides (LDHs) was prepared through the precipitation of metal nitrates and further applied to remove excessive fluoride ions from water. The physical and chemical properties of synthesized materials were examined by powder transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, N2 adsorption/desorption analysis, and thermogravimetric analysis (TGA). The TEM results indicated that the materials synthesized via coprecipitation present a preferential orientation of the nanoscale LDH platelets. The XRD analysis confirmed that the synthesized products have a highly crystalline nature and a well-ordered layer structure. The high specific surface areas (37.24鈥?1.27 m2/g) of calcined products were demonstrated to be beneficial for the adsorption of fluoride. For the adsorption experiment, the effects of the adsorption conditions including pH, coanions and adsorbent dose were investigated at initial fluoride concentration of 20 mg/L. The kinetics and isotherms of fluoride adsorption by calcined Li鈥揂l LDHs were studied. The results indicated that the Li鈥揂l LDHs can be effectively used to remove fluoride from water, where the maximum percentage removal (97.36%) could be reached and the adsorption equilibrium could be attained within 1 h. The kinetic data were well-fitted to the pseudo-second-order model, while the Fre眉ndlich isotherm model provided the better correlation of the equilibrium data. Based on FT-IR and kinetic analysis, the 鈥渕emory effect鈥?may play an important role in the early adsorption stage, while the ion-exchange process may control the adsorption rate at the second adsorption stage. Since the Li鈥揂l LDHs show excellent fluoride removal efficiency, they are expected to separate fluoride from water in pollution control.