铝基吸附剂的制备、表征及对F~-的吸附性能研究

发布时间：2018-01-18 11:16

本文关键词：铝基吸附剂的制备、表征及对F~-的吸附性能研究　出处：《中国科学院大学(中国科学院青海盐湖研究所)》2017年博士论文　论文类型：学位论文

【摘要】：电解铝含氟烟气中氟对人体健康和动植物的生长存在严重危害。本研究以Na F溶液为含氟废水模拟溶液,用铝基吸附剂对其吸附以达到深度去除目的,从而为电解铝含氟烟气中氟化物的二次净化提供参考,并期望在实际除氟过程中得到应用。论文研究了铝基吸附剂的制备、表征、孔结构调控,吸附热力学、动力学、吸附选择性、循环利用性及除氟机理。铝基吸附材料制备简单,孔结构可调控,具有大的比表面积,对F~-具有较高的选择性及吸附容量,且吸附速率快,是一类优异的除氟剂。具体研究内容包括以下4个方面。(1)用水热合成及高温焙烧技术用低成本无机铝源和沉淀剂制备了系列γ-Al_2O_3介孔材料。考察了制备条件对产物晶型、形貌和孔结构性质的影响。结果表明,铝源和沉淀剂类型对产物晶型无控制作用,但对形貌有明显影响。γ-Al_2O_3的BET比表面积、孔体积和孔径大小均可通过改变反应原料进行调控。(2)以葡萄糖为调孔剂,用水解-高温焙烧技术制备了介孔γ-Al_2O_3吸附剂。研究了γ-Al_2O_3对F~-的吸附性能及除氟机理。结果表明,葡萄糖对产物晶型无控制作用,对形貌和孔结构性质有明显影响。γ-Al_2O_3吸附F~-速率较快,吸附过程符合Langmuir单层吸附和准二级动力学模型,最大饱和吸附容量为8.34 mg·g~(-1)。p H对γ-Al_2O_3的zeta电位值和对F~-的吸附有重要影响,但适用的最佳p H范围较窄。共存阴离子对F~-的吸附影响顺序为PO_4~(3-)HCO_3~-SO_4~(2-)NO_3~-Cl~-。γ-Al_2O_3的循环利用性能优异,吸附机理主要包括静电吸引、配体交换、离子交换及氢键作用。(3)以合成的γ-Al_2O_3为基体材料,用原位生长法制备了Mn O_2-Al_2O_3吸附剂。研究了Mn O_2-Al_2O_3的孔结构性质及对F~-的吸附性能和机理。结果表明,Mn O_2-Al_2O_3较γ-Al_2O_3具有更大的BET比表面积和孔体积,孔径分布较窄,具有双峰介孔结构。Mn O_2-Al_2O_3对F~-的吸附速率快,效率高,具有宽泛的p H应用范围(p H=4~10),适合实际工业化应用条件。吸附过程遵循准二级动力学模型,为化学吸附。共存阴离子对F~-的吸附影响顺序为PO_4~(3-)Cl~-SO_4~(2-)NO_3~-HCO_3~-。Mn O_2-Al_2O_3的循环利用性能较γ-Al_2O_3差,结构稳定性有待进一步优化。吸附机理同介孔γ-Al_2O_3的除氟机理。(4)以合成的γ-Al_2O_3和氧化石墨烯(GO)为原料,用水热法合成了GO-Al_2O_3吸附材料,考察了对F~-的吸附行为及机理。结果表明,γ-Al_2O_3在GO上的均匀分散增加了吸附剂的活性位点,提高了BET比表面积,改善了孔结构性质。基于γ-Al_2O_3更多活性位点的暴露和GO提供的活性功能基团,GO-Al_2O_3的吸附容量提升至γ-Al_2O_3的近2倍。GO-Al_2O_3吸附F~-的最佳p H范围较宽,吸附过程符合准二级动力学模型,是介于单层和多层吸附之间的一种模式。共存阴离子对F~-的吸附影响顺序为PO_4~(3-)HCO_3~-SO_4~(2-)Cl~-NO_3~-。GO-Al_2O_3的循环利用性能较γ-Al_2O_3差,结构稳定性有待提高。吸附机理同介孔γ-Al_2O_3的除氟机理。
[Abstract]:Fluoride in fluorine-containing flue gas of electrolytic aluminum is seriously harmful to human health and the growth of animals and plants. In this study, NaF solution was used as the simulated solution of fluorine-containing wastewater, and it was adsorbed with aluminum based adsorbent to achieve the purpose of deep removal. Therefore, it provides a reference for the secondary purification of fluoride in aluminum fluoride-containing flue gas, and expects to be applied in the actual process of fluoride removal. The preparation, characterization, pore structure regulation and adsorption thermodynamics of aluminum based adsorbent are studied in this paper. Kinetics, adsorption selectivity, recycling utilization and fluorine removal mechanism. Al-based adsorption materials have simple preparation, controllable pore structure, large specific surface area, high selectivity and adsorption capacity to F-. And the adsorption rate is fast. Is a class of excellent defluorination agents. The specific research contents include the following four aspects. A series of 纬 -Al _ 2O _ 3 mesoporous materials were prepared by hydrothermal synthesis and high-temperature calcination with low-cost inorganic aluminum sources and precipitators. The preparation conditions of 纬 -Al _ 2O _ 3 mesoporous materials were investigated. The results show that aluminum source and precipitant type have no effect on the crystal form of the product, but have obvious effect on the morphology. The BET surface area of 纬 -Al _ 2O _ 3 is not controlled. The pore volume and pore size can be adjusted by changing the raw material. Mesoporous 纬 -Al _ 2O _ 3 adsorbent was prepared by hydrolysis-high temperature roasting technique. The adsorption properties of 纬 -Al _ 2O _ 3 and the mechanism of fluoride removal were studied. Glucose has no effect on the crystal form of the product, and has obvious influence on the morphology and pore structure. The adsorption rate of F- ~-by 纬 -Al2O3 is faster than that of 纬 -Al _ 2O _ 3. The adsorption process accords with Langmuir monolayer adsorption and quasi-second-order kinetic model. The maximum saturated adsorption capacity is 8.34 mg 路g ~ (-1) ~ (-1) ~ (-1) 路p ~ H, which has an important effect on the zeta potential of 纬 -Al _ 2O _ 3 and the adsorption of F ~ (2 +) ~ (-). However, the optimum pH range is narrower. The order of influence of coexisting anions on Fn- adsorption is PO4 / HCO3- so _ 4 / _ _ _ (_ _ _. The number of no _ 3 / C _ (3) -Cl _ (-) 纬 -Al _ 2O _ 3 has excellent recycling performance. The adsorption mechanism mainly includes electrostatic attraction, ligand exchange, ion exchange and hydrogen bonding. In situ growth method was used to prepare the adsorbent of MNO _ 2-Al _ 2O _ 3. The pore structure properties, adsorption properties and mechanism of mn _ O _ 2-Al _ 2O _ 3 were studied. Compared with 纬 -Al _ 2O _ 3, Mn-O _ 2-Al _ 2O _ 3 has larger BET surface area and pore volume and narrower pore size distribution. It has a bimodal mesoporous structure. Mn-O _ 2-Al2O3 has a fast adsorption rate and a high efficiency for F-, and has a wide range of pH applications. The adsorption process follows the quasi-second-order kinetic model. For chemisorption, the order of influence of coexisting anions on the adsorption of Fn- is POST-4CONTAL 3-CONCLON-SO4CONTAL 2). The recycling performance of NO_3~-HCO_3~-.Mn O _ 2-Al _ 2O _ 3 is worse than that of 纬 -Al _ Als _ 2O _ 3. The adsorption mechanism of 纬 -Al _ 2O _ 3 is the same as that of mesoporous 纬 -Al _ 2O _ 3. GO-Al_2O_3 adsorption materials were synthesized by hydrothermal method. The adsorption behavior and mechanism of F- were investigated. The homogeneous dispersion of 纬 -Al2O3 on go increased the active sites of adsorbent and increased the specific surface area of BET. The pore structure properties were improved. Based on 纬 -Al _ 2O _ 3, more active sites were exposed and the active functional groups provided by go. The adsorption capacity of GO-Al_2O_3 was increased to nearly twice as much as that of 纬 -Al _ 2O _ 3. The optimum pH range for the adsorption of F- by GO-Al _ 2O _ 3 was wider. The adsorption process accords with the quasi-second-order kinetic model. It is a model between monolayer and multilayer sorption. The order of influence of coexisting anions on Fn- adsorption is POS4 / HCO3 / SO4 / 2). The recycling performance of Cl~-NO_3~-.GO-Al_2O_3 is worse than that of 纬 -Al _ S _ 2O _ 3. The mechanism of adsorption is the same as that of mesoporous 纬 -Al _ 2O _ 3.
【学位授予单位】：中国科学院大学(中国科学院青海盐湖研究所)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O647.3

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