【作者】 郑春明；

【导师】 关乃佳；

【作者基本信息】 南开大学 ， 材料物理与化学， 2009， 博士

【摘要】 随着当今表面科学与复合材料研究的深入,多孔无机/聚合物复合材料由于其独特的性能越来越引起学界的关注,它部分克服了单一材料和传统复合材料性能上的缺陷,使材料既具有无机材料的优点（如刚性和高热稳定性等）,又具有聚合物材料的优点（如弹性、介电性、延展性和可加工性等）,特别是多孔无机物在聚合物基体中均匀分布,材料表面易于功能化、无机材料孔径可控、无机-有机组成调节范围大等特性,赋予了这类复合材料在生物学、环境和化工等方面的附加性能。本文以硫酸铝、多孔硅胶、水玻璃为前驱体制备无机多孔材料,在无机物制备过程中加入海藻酸钠、壳聚糖等有机物,采用直接混合、无机粒子表面改性、原位生成法制备了多种多孔无机/聚合物复合材料,并用于酵母固定化生物催化生产燃料乙醇和脱色净化生产高品质白砂糖产业生产过程。主要开展了以下几个方面的研究工作:（1）以硫酸铝为拟薄水铝石前驱体,通过原位生成过程制备拟薄水铝石/海藻酸复合材料。详细研究了复合材料孔道,表面结构和机械性能,并采用吸附与包埋耦合方法在复合材料制备过程中加入酵母细胞,制备拟薄水铝石/海藻酸复合固定化酵母,研究了以甘蔗废糖蜜生产燃料乙醇的酵母固定化发酵性能。通过复合材料固定化酵母增殖机理及SEM、TEM等表征发现固定化酵母细胞密度高,达4.1×10⁹ mL^-1,甘蔗废糖蜜批式发酵初始糖浓度165 g·L^-1,14 h内乙醇浓度可达77.4 g·L^-1,总糖利用率90.5%,糖醇转化率98.3%,显示了良好的发酵性能。（2）采用无机颗粒表面接枝改性的方法制备表面带有伯氨基反应性功能团的HY、MCM-41等多种分子筛与有机物包埋相结合,借助吸附和包埋耦合方法固定化酵母,制备了多种改性分子筛/海藻酸复合材料。发现介孔MCM-41分子筛对海藻酸改性复合材料（H₂NMCM-41/ALG）在上述分子筛复合材料中具有最高的酵母包埋活性,研究了H₂NMCM-41/ALG复合固定化酵母以甘蔗废糖蜜生产燃料乙醇的发酵性能及复合材料固定化酵母增殖机理,固定化酵母浓度达4.8×10⁹ mL^-1,甘蔗废糖蜜批式发酵初始糖浓度170 g·L^-1,12 h内乙醇浓度可达78.6 g·L^-1,总糖利用率89.2%,糖醇转化率96.3%,乙醇发酵过程彻底、速率快、残糖水平低,原料利用率和发酵醪乙醇浓度均超过传统工艺。3)在得出拟薄水铝石/海藻酸复合材料具有较好的酵母固定化性能和发酵性能以后,本文使用吸附-包埋耦合的方法以拟薄水铝石/海藻酸复合材料对酿酒酵母进行固定化,并进行了30 L×2和10 M³×2两种规模的中试连续发酵试验,系统研究了稀释率、温度、pH、填充率、初始糖浓度对拟薄水铝石/海藻酸复合固定化酵母发酵性能的影响。结果表明,甘蔗废糖蜜连续发酵初始糖浓度169g·L^-1,填充率15%条件下,9.2 h内乙醇浓度可达76.1 g·L^-1,总糖利用率87.2%,糖醇转化率96.3%。燃料乙醇发酵工艺与传统工艺相比,单位生产成本降低4.85%,同等规模发酵速率提高4.96倍,发酵周期缩短78.1%,设备容积减少76.2%,投资总额减少70.4%。工艺流程短,降低了原料生产成本,适合于糖业界快速改造大规模生产乙醇,可达到投资省,产率高,性能稳定的目的。（4）针对于现今白砂糖生产二氧化硫残留量高,生产产品品质波动大的特点,本文以多孔硅胶、水玻璃为硅源前驱体,通过直接混合,无机粒子表面改性和原位生成法制备了多种二氧化硅/壳聚糖复合材料用于赤砂糖回溶糖浆脱色净化实验。发现原位二氧化硅/壳聚糖复合材料具有最佳的脱色净化性能,在脱色温度75℃,体积空速3.0 h^-1,赤砂糖回溶糖汁浓度30°Bx条件下,脱色率94.2%,简纯度差11.20,脱色容积可达35 BV。通过SEM、TEM等表征发现材料有机-无机相结合紧密,并在吸附有色分子、对压榨蔗汁脱色方面具有优异的性能。（5）选取原位生成二氧化硅/壳聚糖复合材料,详细研究了复合材料对甘蔗压榨糖汁和糖浆脱色净化原料、色值,空速等影响条件和寿命、重复再生性能等。与制糖企业合作,进行了12 L规模小试试验,其中以混合汁生产的白砂糖在原料及生产正常情况下可不使用二氧化硫,以澄清汁生产的白砂糖除SO₂含量为优级外,其余指标已达到国家GB317-2006精糖标准。改变了壳聚糖单独使用价格高,生成凝聚物分离困难,恰当的壳聚糖投入量不易掌握的缺点,解决了传统亚硫酸法蔗糖二氧化硫残留含量高,食品安全性低的问题,减少环境污染,吨糖成本预计仅为22.2元。操作工艺和成本分析表明,原位生成二氧化硅/壳聚糖对甘蔗压榨糖汁和糖浆脱色净化生产高品质白砂糖是经济可行的。文通过调节多孔无机/聚合物复合材料无机-有机组成范围及工艺过程的研究,采用耦合固定化、原位生成等方法设计固定化酵母多孔无机/聚合物复合材料和脱色净化多孔无机/聚合物复合材料。并以此为基础,开展以甘蔗废糖蜜和甘蔗压榨糖汁和糖浆为原料的中试试验。利用中试结果进行技术经济成本研究,进一步分析制糖企业提高生产效率,降低成本的关键工艺和生产环节,为制糖企业生产可再生能源和提高食品生产质量,降低最终产品制造成本,优化燃料乙醇及高品质白砂糖生产工艺提供理论依据,为实现糖业中燃料乙醇及高品质白砂糖的绿色高效生产新工艺提供技术支持。更多还原

【Abstract】 With the development of the surface science and research of the composite materials, porous inorganic/polymer composite obtained more and more concerns of the academic because its unique properties. It has overcome some defects of the homogeneous materials and traditional composite materials. The composite not only has the advantages of inorganic material （such as stiffness and heat stability）, but also has the advantages of polymer material （such as flexibility, dielectric properties, ductility and machinability）. The inorganic porous particles in polymer matrix distributed uniformly, modified easily in the polymer matrix, controlled easily of the particle size, all these features give this kind of composite good performance in biology, environmental and chemical aspects.In this paper, aluminum sulfate, porous silica and water glass were used as the precursors of inorganic porous materials. In the preparation process of inorganic porous materials, organic materials, such as sodium alginate and chitosan, were added into inorganic porous materials with the in-situ generation method, and the porous inorganic/polymer composite was obtained at last. The composite was used to immobilize yeast cells as biocatalyst to produce fuel ethanol and to decolorize and purify sugarcane syrup in the process of high quality white sugar production. The research work mainly carried out in the following fields:1. Aluminum sulfate was used as the precursor of the pseudo-boehmite, and the pseudo-boehmite/alginate composite was prepared with the in-situ synthetic method. A detailed research of pore size, surface structure and mechanical properties of the pseudo-boehmite/alginate composite was studied. Then the composite was used to immobilize yeast cells with the coupling immobilization method of adsorption and embedment. The ethanol fermentation performance of the pseudo-boehmite/alginate immobilized yeast was studied using sugarcane molasses. With the research of proliferation mechanism, SEM, TEM characterization, pseudo-boehmite/alginate immobilized yeast showed yeast cell immobilized density at 4.1×10⁹ mL^-1, and good fermentation performance.2. Through the combining method of inorganic surface modification with a primary amino-reactive functional groups and organic embedding, a variety of modified zeolite/alginate composites were prepared by the coupling immobilization of physical adsorption and embedding. It was found that mesoporous molecular sieve MCM-41/alginate composite showed the highest fermentation activity of the yeast in the production of fuel ethanol with sugar cane molasses as raw stuff. The proliferation mechanism of the MCM-41/alginate immobilized yeast and the SEM of the carriers revealed the composite carrier is porous, which facilitates the transmission of substrates and products between carriers and medium. The experiments show that the composite carrier of MCM-41/alginate immobilized yeast has higher carrier ethanol productivity, lower residual sugar concentration than traditional technology, and can get higher conversion ratio of material and ethanol concentration.3. For the pseudo-boehmite/alginate immobilized yeast has the good immobilization and fermentation performance, pseudo-boehmite/alginate immobilized yeast was used in pilot-scale continuous fermentation experiments of 30 L×2 and 10 m³×2. The experiments showed that the immobilized yeast of pseudo-boehmite/alginate has higher ethanol fermentation rate, lower residual sugar concentration than traditional technology, and can get higher conversion ratio of material and ethanol concentration. The new kind of fermentation process can reduce the production costs of raw materials. It is suitable for the sugar industry to produce the fuel ethanol in the large-scale.4. In the current sugar production, the residual sulfur dioxide concentration remains high, and the characteristics of the white sugar product is unsteady. All of these defeats are harmful to human health. In this article, porous silica and water glass was used as the precursor of silica source, with the methods of surface modification of inorganic particles and in-situ synthetic, several types of silica/chitosan composites was prepared and used in the decolorization and purification process of sugarcane juice and syrup. The in-situ synthetic silica/chitosan composites has the best performance in the detreated purification. Through SEM, TEM characterization, the interface of inorganic-organic of the composites was compact, and the in-situ synthetic silica/chitosan composite has excellent performance in the absorption of non-ferrous elements and sugarcane juice and syrup.5. In-situ synthetic silica/chitosan composites was studied with detail, such as effect of temperature, LHSV, and duplicate renewable abilities in the red sugar remelting juice. With the help of Yunnan sugar factory, 12 L pilot-scale experiments of in-situ synthetic silica/chitosan composites were carried out, the decolorization ratio of syrup was higher than 80% with easy operation method and low cost, which played an important role in upgrading sugar products and environmental protection.更多还原