功能化MCM-41介孔材料的制备及其吸附稀土离子的性能研究

发布时间：2018-06-13 01:00

本文选题：稀土 + 吸附　；参考：《南昌大学》2017年硕士论文

【摘要】：本文针对稀土资源开采过程中出现的回收不彻底、浪费严重等现状,以绿色环保化学理念为指导,以MCM-41为基体,成功制备两种经硅烷偶联剂改性的新型中孔硅基材料。分别用于轻稀土离子La~(3+)、中稀土离子Gd~(3+)及重稀土离子Yb~(3+)的富集回收实验。根据实验结果,本文系统的探究了三种吸附剂对低浓度稀土离子的吸附及脱附行为。首先,采用水热合成法,以正硅酸乙酯(TEOS)作为硅源,以十六烷基三甲基溴化铵(CTAB)作为模板剂,简单高效的合成MCM-41分子筛,其BET孔径及比表面积分别为2.94 nm、1114.8 m~2/g。通过加入APTES和MPTES这两种偶联剂,对其进行孔道内修饰,分别制备出了经胺基、巯基功能化的NH_2-MCM-41和SH-MCM-41介孔材料,其BET孔径及比表面积分别为2.15 nm、956.2 m~2/g和2.10 nm、956.0 m~2/g。偶联剂成功进入MCM-41基体内部,实现了孔道内表面修饰。其次,以合成的MCM-41、NH_2-MCM-41和SH-MCM-41为吸附剂,稀土离子La~(3+)、Gd~(3+)和Yb~(3+)为吸附质,对吸附单因素条件、等温吸附、热力学、动力学、吸附机理及再生性能进行探究。实验表明:MCM-41吸附剂对稀土离子La~(3+)、Gd~(3+)和Yb~(3+)的最大吸附量分别为434.08 mg/g、418.42 mg/g和492.40 mg/g;Fe~(3+)、Al~(3+)、Ca2+、Mg2+及NH4+五种干扰离子对稀土离子吸附量的影响:三价离子能与稀土离子形成竞争吸附从而降低其吸附量,其他离子对其吸附量影响很小。胺基的最佳(以N计)接枝量是1.98%,NH_2-MCM-41对Yb~(3+)的最大吸附量为709.70mg/g。吸附过程符合Freundlich等温吸附模型,动力学可以用准二级速率方程进行描述。巯基的最佳(以S计)接枝量是6.06%;SH-MCM-41对La~(3+)、Gd~(3+)和Yb~(3+)的饱和吸附量分别达到了560.56 mg/g、507.85 mg/g和540.68 mg/g。最后,分别以盐酸、硝酸和柠檬酸作为解吸剂,对吸附剂的洗脱及再生性能进行探究。从绿色化学出发,最佳解析条件是:2 mol/L的盐酸溶液,解析1 h,SH-MCM-41吸附剂对La~(3+)、Gd~(3+)和Yb~(3+)初次解析率分别达到了93.4%、92.1%和95.3%左右;重复使用4次,吸附剂对稀土离子的吸附率均保持在80%以上,说明合成的吸附剂有良好的水热稳定性,可循环再生,节约吸附成本。
[Abstract]:In this paper, two new mesoporous silicon-based materials modified by silane coupling agent were successfully prepared under the guidance of green environmental chemical idea and MCM-41 matrix in view of the incomplete recovery and serious waste during the process of rare earth resource exploitation. It has been used for the enrichment and recovery experiments of light rare earth ions Lahuo 3, medium rare earth ions Gdl3) and heavy rare earth ions Ybt3), respectively. Based on the experimental results, the adsorption and desorption behavior of three kinds of adsorbents for rare earth ions with low concentration were systematically investigated. Firstly, using tetraethyl orthosilicate (TEOS) as silicon source and cetyltrimethylammonium bromide (CTAB) as template, MCM-41 molecular sieve was synthesized by hydrothermal method. The BET pore size and specific surface area of MCM-41 molecular sieve were 2.94 nm and 1114.8 mg / g, respectively. By adding APTES and MPTES, the mesoporous materials of NH2-MCM-41 and SH-MCM-41 were prepared. The pore size and specific surface area of BET were 2.15 nm ~ 956.2 m ~ (2 / g) and 2.10 nm ~ 956.0 m ~ (-2 / g), respectively, and the mesoporous materials of NH2-MCM-41 and SH-MCM-41 were prepared. The coupling agent successfully entered the MCM-41 matrix and realized the inner surface modification of the pore channel. Secondly, using the synthesized MCM-41 and SH-MCM-41 as adsorbents, rare earth ions Lazhu3 (Gddf3) and Ybc3) as adsorbents, the adsorption conditions, isotherms, thermodynamics, kinetics, adsorption mechanism and regeneration properties of MCM-41 and SH-MCM-41 were investigated. The experimental results show that the maximum adsorption capacity of the adsorbents for rare earth ions Laohou 3 (GdDH3) and Ybn3) are 434.08 mg / g ~ 418.42 mg/g and 492.40 mg / g / g ~ (3) C ~ (2 +) respectively. The effects of five kinds of interference ions, such as Ca ~ (2 +), mg _ (2) and NH _ 4, on the adsorption capacity of rare earth ions are as follows: the three valence ions can compete with the rare earth ions in the adsorption capacity of rare earth ions: three valence ions can compete with rare earth ions in the adsorption capacity of rare earth ions. To reduce the amount of adsorption, Other ions have little effect on the adsorption capacity. The best grafting amount of amino group is 1.98% NH _ 2-MCM-41 and the maximum adsorption capacity is 709.70 mg 路g ~ (-1) 路m ~ (-1) 路min ~ (-1) 路min ~ (-1). The adsorption process is in accordance with Freundlich isothermal adsorption model and the kinetics can be described by quasi second order rate equation. The optimum grafting capacity of thiol group is 6.06g / g SH-MCM-41, and the saturated adsorption capacity of Ybf3 is 560.56 mg / g / g ~ 507.85 mg/g and 540.68 mg / g / g, respectively, and the saturated adsorption capacity of SH-MCM-41 is 560.56 mg / g / g and 540.68 mg / g / g, respectively, and the saturated adsorption capacity of thiol group is 560.56 mg / g / g and 540.68 mg / g / g, respectively. Finally, hydrochloric acid, nitric acid and citric acid were used as desorption agents to study the elution and regeneration of adsorbent. From green chemistry, the best analytical conditions are: 1 mol / L hydrochloric acid solution, 1 h SH-MCM-41 adsorbent for Lazhiyang3 (GdDX 3) and Ybzao 3) for the first time resolution rates of 93.4% and 95.3% respectively, and repeated use for 4 times, and the optimum analytical conditions are as follows: (1) the first analytical rate is about 93.1% and 95.3% respectively, and the first analytical rate is about 93.4% and 95.3% respectively. The adsorption rates of rare earth ions were above 80%, which indicated that the synthesized adsorbents had good hydrothermal stability, could be recycled, and the adsorption cost could be saved.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.4;O647.3

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