【作者】 黄茂辉；

【导师】 陈汝芬； 葛小鹏；

【作者基本信息】 河北师范大学 ， 无机化学， 2010， 硕士

【摘要】 Al₁₃是Al3+在强制水解过程中形成的具有Keggin结构的铝的形态,其化学式为Al₁₃O₄（OH）₂₄（H₂O）₁₂⁷⁺,由于其高电荷性质,有利于对水体中颗粒物进行吸附电中和,使颗粒物脱稳、聚集、沉降,从而达到水质净化的目的。人们通常用Al₁₃的含量来评价无机高分子絮凝剂PAC的质量。本文通过微量滴碱法,制备了不同碱化度的PAC,并通过SO₄^2-/Ba²⁺沉淀置换法提纯了Al₁₃,通过高岭土模拟废水验证了不同碱化度PAC及Al₁₃的混凝性能;通过St（o|¨）ber方法制备了亚微米级的粒度分布均匀的SiO₂球形颗粒;并以此SiO₂作为载体,通过静电自组装的方法制备了SiO₂@Al₁₃核壳结构复合材料,讨论了不同条件对复合材料制备的影响,并通过混凝实验对其性能进行了验证,以期充分发挥颗粒粒度效应,而提高其混凝效果,增加其应用性。。研究内容主要包括:（1） PAC及Al₁₃的制备及其混凝特性通过微量滴碱法制备了PAC,并通过SO42-/Ba2+沉淀置换法提纯了Al₁₃,研究了碱化度对Al形态分布的影响。研究表明:对于PAC,在碱化度B=0.5¹.5时,Alb的含量较低,不到50%;随着碱化度的升高,在B=2.0².5时,Alb的含量达到了60%以上。经过提纯后的Al₁₃中,Alb的含量达到了90%以上,并且随着碱化度的增加,形成了不同聚集度的Al₁₃聚集体,其Ferron活性降低了,Alb的含量也降低到了60%左右。混凝实验表明,高碱化度的PAC电中和能力较强,其浊度去除效果较好;而对于Al₁₃来说,随着碱化度的增加,Al₁₃聚集体的电中和能力及混凝特性都相对的降低了。（2）单分散二氧化硅的制备和表征采用St（o|¨）ber方法制备了粒径分布均匀的亚微米级二氧化硅。研究表明:随着加水浓度的增加,二氧化硅的平均粒径从170nm增加到了200nm,这主要受到反应初期不稳定晶核数量的影响造成的;随着氨水浓度的增加,二氧化硅的平均粒径也增加了,这主要是受到水解反应速率的影响;由于TEOS浓度的增加,三维网络链的数量增加了,从而也促进了二氧化硅平均粒径的增加。通过优化调控各种因素,可以制备出所需粒度的均匀的SiO₂球形颗粒。所制备的二氧化硅表面孔多为介孔分布,在pH=4⁹时,二氧化硅表面呈负电性。（3） SiO₂@Al₁₃核壳结构材料的制备及混凝特性通过静电自组装的方法制备了SiO₂@Al₁₃核壳结构材料。研究表明:随着Al/Si的增加,Al₁₃在二氧化硅表面的负载量不断增加,当Al/Si>1:1时,Al₁₃在二氧化硅表面包覆量的增加变化不大;随着反应温度的升高,Al的负载量不断减小,高温不利于Al₁₃在二氧化硅表面的负载;随着碱化度的增加,Al₁₃通过OH-连接成Al₁₃的聚集体,增加了空间位阻效应,同样不利于负载。通过分析表明,Al₁₃在二氧化硅表面的作用属于物理作用。混凝实验表明,复合材料相对于Al₁₃来说,由于颗粒粒度效应,其所形成的颗粒较大,浊度去除效果较好。更多还原

【Abstract】 Al₁₃(Al₁₃O₄（OH）₂₄（H₂O）₁₂⁷⁺) with a Keggin structure is the formation of aluminum in the process of forced hydrolysis of Al3+. Due to the highly charge, it is beneficial for adsorpting and charge neutralizatiing of particles in water. And then, the particles off-steadied, aggregated, settled, so as to achieve the purpose of water purification. The quality of inorganic polymer flocculants polyaluminum chloride（PAC） is used to be evaluated by the content of Al₁₃.In this paper, we prepare different basic PAC through micro-drops of alkali method and purify Al₁₃ by SO₄^2-/Ba²⁺ precipitation replacement method. Meantime, we verify coagulation performances of PAC and Al₁₃ in the kaolin wastewater. Uniform SiO₂ spherical particles distributing in sub-micron particle sizes are prepared by St（o|¨）ber method. Then, SiO₂@Al₁₃ core-shell structure composite material is prepared by electrostatic self-assembly. We discuss the different reacted conditions exerting the effect on the preparation of composite material. Its coagulation performances is tested for playing particle size effect to increase its applicability.The study includes the following parts.（1） Preparation and coagulation performances of PAC and Al₁₃PAC of different basic are prepared by the micro-drops of alkali method and Al₁₃ are purified by SO42-/Ba2+ precipitation replacement method. We discuss different basicity producing effect on the Al morphology distribution. Studies have shown that, for PAC, the content of Alb are less than 50% when the basic（B） in ranging from 0.5 to 1.5;as with the increasing of basic up to rang from 2.0 to 2.5,the content of Alb reaches more than 60%. Alb levels reached more than 90% in purified Al₁₃.Because of the formation of Al₁₃-aggregates which reduce the Ferron activity,the content Alb reduced to 60%. Coagulation tests show that, highly basic PAC have the stronger capacity of electric-natrual, so it show up better turbidity removal efficiency.While for Al₁₃ with the increase in basic, the capacity of electric-natrual of Al₁₃-aggregates are relatively reducing.（2） Preparation and Characterization of mono-dispersed silica dioxide Uniform size distribution of sub-micron silicon dioxide is prepared with St（o|¨）ber method. Research shows that, with the increasing concentration of water, average particle sizes of silicon dioxide range from 170nm to 200nm mainly effected by the number of unstable nuclei during the initial reaction; average particle sizes also similarly increase with the increasing concentration of ammonia mainly effected by the hydrolysis reaction rate; because of increasing TEOS concentration, the number of three-dimensional network of chains also contributes to the increase in average particles size of silica dioxide. Optimizing the variety of factors, we can prepare the required size of uniform SiO₂ spherical particles. Mesoporous distributes on the spherical surface and the surface possesses negative charge in pH=4⁹.（3） Preparation and coagulation properties of SiO₂@Al₁₃ core-shell structure materialSiO₂@Al₁₃ core-shell structure materials are prepared through electrostatic self-assembly method. Researches show that, with the ratio of Al/Si increasing, the content of Al₁₃ loading on silica surface increase; when the ratio up to more than 1:1,Al₁₃ coating on the surface have little change. With reaction temperature increasing, the amount of Al decreases, so high temperature have a negative effect on the coating of Al₁₃ on the spherical surface. The increasing basic, because of the information of Al₁₃-aggregates connecting by OH-, the steric effect is not beneficial for the loading. The analysis show that, the roles on the silica surface are physical effects. Coagulation experiments show that, relativing to the pure Al₁₃, SiO₂@Al₁₃ composite materials form large particle size and the turbidity removal effect is better for the particle size effect.更多还原