钼酸根阴离子印迹陶瓷膜的制备与吸附性能

以三氧化二铝陶瓷膜为载体,以钼酸根阴离子为模板离子,1-乙烯基咪唑为功能单体,1,6-二溴己烷为交联剂,采用表面印迹和接枝聚合方法制备了能选择性吸附Mo(Ⅵ)的新型印迹陶瓷膜(IIP-PVI/CM).采用红外光谱、X射线光电子能谱、热重分析及扫描电子显微镜等方法对陶瓷膜进行结构表征.研究了pH值对吸附性能的影响,当pH值范围为2~4时,IIP-PVI/CM具有良好吸附能力;动力学和热力学结果表明,IIP-PVI/CM对Mo(Ⅵ)的吸附符合准二级动力学模型和Langmuir吸附模型;当pH=4.0和温度为30℃时,IIP-PVI/CM对Mo(Ⅵ)具有良好选择性,Mo(Ⅵ)对W(Ⅵ)的选择性系数高达7.48;动态吸附结果表明,IIP-PVI/CM对W(Ⅵ)和Mo(Ⅵ)的吸附饱和时间分别为24和47 min,饱和吸附量分别为0.163和0.672 mmol/100 g,动态吸附时IIP-PVI/CM亦具有良好选择性;经9次吸附与解吸后,IIP-PVI/CM对Mo(Ⅵ)吸附容量仍可达到初始值的92%,再生和循环使用性能良好.

Preparation and Adsorption Properties of Molybdate Anion Imprinted Ceramic Membrane

A novel imprinted ceramic membrane ( IIP-PVI/CM) for adsorbing selectively molybdate anion [ Mo(Ⅵ) ] was prepared with surface imprinting technology and graft-polymerization using an alumina ceramic membrane as the supporting material, Mo (Ⅵ) as the template ion, 1-vinylimidazole as the functional monomer and 1, 6-dibromohexane as the cross-linking agent. The obtained samples were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis and scanning electron microscopy. Effect of pH value on adsorption performance of IIP-PVI/CM was investigated. The results indicate that IIP-PVI/CM shows a good adsorption capacity in the pH range of 2—4. The adsorp-tion behaves of IIP-PVI/CM toward Mo (Ⅵ) were studied through adsorption kinetics and thermodynamics. The kinetics curve meets pseudo-second-order model. The adsorption isotherm can be described by Langmuir isotherm model. The selective adsorption experiment for IIP-PVI/CM was carried out at pH of 4. 0 and temperature of 30 ℃ by a mixed solution containing 4 mmol/L Mo(Ⅵ) and 4 mmol/L W(Ⅵ) . It was found that IIP-PVI/CM has specific selectivity for Mo(Ⅵ), and the selectivity coefficient is 7. 48 for Mo(Ⅵ) to W(Ⅵ) . A dynamic adsorption experiment was done by a membrane apparatus. The results indicate that IIP-PVI/CM also shows good selectivity for separation of Mo(Ⅵ) and W(Ⅵ). The values of the saturated adsorption time of W(Ⅵ) and Mo(Ⅵ) anions are 24 and 47 min, corresponding to the saturated adsorption amounts of 0. 163 mmol/100 g for W (Ⅵ) and 0. 672 mmol/100 g for Mo (Ⅵ) , respectively. After nine adsorption-desorption cycles, the adsorption capacity of IIP-PVI/CM towards Mo(Ⅵ) still reaches 92% of the initial capacity. The IIP-PVI/CM has good regeneration and recycling performance.