【作者】 刘石峰；

【导师】 杨立新；

【作者基本信息】 湘潭大学 ， 无机化学， 2010， 硕士

【摘要】 锂是人们生产生活中的重要金属。在过去的半个世纪里多种用于从盐湖卤水和海水中提取锂的方法如溶剂萃取法、沉淀法和离子交换吸附法等已被广泛地研究。其中吸附剂法由于某些特定的无机筛分材料展现出对Li+极高的选择性和环境友好效应被认为是最有前途的方法。多种锂锰氧化物特别是具有尖晶石相的锂锰氧化物吸附剂已经被研究和表征。然而粘结剂的堵塞和固相中的扩散阻力抑制了吸附剂的吸附特性,且在Li+的脱嵌过程中,锰的变价导致吸附剂容易发生溶损。为了克服这些缺点,本工作从材料的化学组成和结构两方面对吸附剂进行了改性研究。通过引进稳定的三价元素,改变材料的组成,提高了吸附剂的稳定性;把吸附剂制成三维有序大孔材料,改善了离子传输性能。本论文主要包括以下四个部分:胶体晶体模板的制备、三维有序大孔锂铝锰氧化物的制备、前驱物的酸处理和锂离子筛的吸附特性研究。分别通过微乳液聚合法、无皂乳液聚合法以及溶胶-凝胶法制备了单分散性聚甲基丙烯酸甲酯、聚苯乙烯和二氧化硅微球,经离心沉降和自然沉降组装了三维有序胶体晶体模板。考察了制备条件对微球直径的影响以及组装方法对胶体晶体模板品质的影响。在聚甲基丙烯酸甲酯胶体晶体模板中填充硝酸锂、硝酸铝和醋酸锰的混合溶液制备了铝掺入的三维有序大孔锂铝锰氧化物LiAlMnO4。材料的微观形貌和大孔尺寸使用场发射扫描电子显微镜（SEM）进行观察,观察前样品表面经过¹00 s的喷金处理;样品的晶相和晶粒尺寸使用粉末X-射线衍射仪（XRD）测定;BET比表面积用表面积分析仪测定,吸附前样品在100℃过夜脱气处理。考察了制备条件对三维有序大孔锂铝锰氧化物的形貌和晶体结构的影响。样品经过盐酸和过硫酸铵溶液脱锂处理后,获得了相应的新型三维有序大孔锂离子筛HAlMnO₄。实验表明其孔径和孔壁厚度分别为240 nm和52 nm左右,X-射线衍射峰归属于纯尖晶石相。在0.1 mol/L HCl溶液中,锂离子的脱出率达到97%以上,同时锰和铝的溶损由于铝对三价锰的替代,有效抑制了Jahn-Teller效应对固体结构的影响,分别只有0.23%和0.45%。对所制备的吸附剂的吸附性能研究表明,锂离子的最大吸附量为45.5 mg/g,达到了HAlMnO4理论吸附量的96.3%。与此同时锂离子的吸附速率明显加快,在与Na⁺、K+、Mg²⁺和Ca²⁺共存的溶液中吸附剂对Li+具有很高的选择性。因此该离子筛材料表现出优异的性质,有希望应用于从极稀溶液中锂的提取。更多还原

【Abstract】 Lithium is an important metal of promoting the world forward. In the past half century, several methods like solvent extraction, precipitation, and ion exchange, etc. have been extensively investigated for lithium recovery from seawater and salt lake brine. Among them, the adsorption method is considered to be the most promising scheme because certain inorganic sieve materials exhibit an extremely high selectivity for Li+ and environmentally friendly effect. Multiple kinds of lithium manganese oxide especially including spinel phase have been studied and characterized. However, the blockage of binder and the diffusion resistance in solid phase suppress the adsorption capacities of adsorbents, and the variable valence of manganese is liable to dissolution in the Li+ extraction/insertion process. In order to overcome the shortcomings, chemical doping and three-dimensinally ordered macropores can be applied to improve the lithium ion-sieve. Chemical doping improved the stability of materials, and three-dimensinally ordered macropores enhanced the diffusion ability of Li+ and the ion-exchange capacity. This work includes four parts: preparation of colloidal crystal template; synthesis of three-dimensinally ordered macropore LiAlMnO4; acid treatment of precursor and adsorption properties of lithium ion-sieve.PMMA, PS and SiO2 monodisperse microsphere was prepared by the method of emulsion polymerization, emulsifier-free emulsion polymerization and sol-gel, respectively, and assembled to colloidal crystal template by centrifugal sedimentation or natural sedimentation. The influences of preparative conditions to the diameter of microspher and assembly methods to the quality of template had been investigated.The Al-incorporated three-dimensionally ordered macroporous lithium manganese oxide LiAlMnO4 is synthesized by the polymethyl methacrylate colloidal crystal template filled with the LiNO3, Al（NO3）3·9H2O and Mn（Ac）2·4H2O mixed solution. The microcosmic morphology and macroporous size were observed using a fieldemission scanning electron microscope （SEM）, the sample surface being sprayed with gold for ¹00 s as pretreatment. Powder X-ray diffractometry （XRD） was used for the characterization of crystal phase and the estimation of the crystalline size. The BET surface area was measured by using a surface area analyzer, samples being degassed at 100℃overnight before sorption measurements. The influences of preparative conditions to the morphology and crystal structure of three dimensinally ordered macoporous lithium manganese oxide had been studied.The corresponding HAlMnO4 as a lithium ion-sieve is obtained after extracting of Li+. The experiments show that the macroporous diameter and porous wall thickness are 240 nm and 52 nm or so, respectively, and the X-ray diffraction patterns of samples belong to the pure spinel phase. The Li+ extraction rate of LiAlMnO4 reaches above 97% in the 0.1 M HCl solution, while the solution losses of aluminum and manganese only have 0.45% and 0.23%, respectively, owing to the substitution of aluminium for tervalence manganese, the influence of the Jahn-Teller effect on the solid structure is suppressed effectively.The Li⁺ maximum uptake capacity is equal to 45.5 mg/g, reaching 96.3% of the theoretical value of HAlMnO4. Meanwhile, the uptake speed of Li+ is obviously speeded up, and there is the quite high selectivity of Li+ in the solution containing K+, Na+, Mg2+ and Ca²⁺. Therefore, this material presents excellent properties and is promising in the lithium extraction from extremely dilute solution.更多还原