双极膜电渗析应用于有机酸的生产

发布时间：2018-05-19 20:14

本文选题：有机酸 + 双极膜电渗析(BMED)　；参考：《合肥工业大学》2017年硕士论文

【摘要】：有机酸是工业生产过程中重要的工业原料,广泛的应用于制药、食品、日化等行业。传统的生产方法有发酵法和化学合成法。发酵法是一种较为温和的生产方式,使用的是可再生原料且来源充足。相比之下,化学合成法目的性强,生产条件较为严苛,且一些有机酸的生产利用化学合成法比较困难。不论是发酵法或化学合成法,生产过程中都会涉及到产品的分离、纯化,常需要提取、结晶、蒸馏等传统的化工单元操作,在分离和纯化过程中不可避免的会产生大量的污染物,需要较高的能量损耗,难以满足当今社会提出的“绿色生产”的要求。将新型的膜分离技术,特别是电渗析技术应用于甲酸、乙酸、柠檬酸等小分子有机酸生产的实例已有大量的报道,但当有机酸分子量比较大的时候,利用膜技术进行生产的效率将会大大降低,因其透过膜迁移的阻力比较大,而难以实现较高的产率,因此我们提出制备合适孔径的离子交换膜以提高有机酸的产率,降低过程的能耗。此外,氨基酸作为一种特殊的有机酸,在医药、食品、动物饲料等领域中有广泛的应用。氨基酸分子中兼含羧基和氨基,其传统分离方法如结晶法、离子交换法、特殊沉淀法等过程较为复杂,结晶过程中的蒸发耗能很大,树脂需要再生耗费较多的化学试剂,特殊沉淀法过程中的沉淀剂难以有效回收,造成大量废液排放。本文以苏氨酸为例,发酵法生产苏氨酸过程中产生的发酵母液会含有一定量的苏氨酸、谷氨酸以及其他杂质成分,双极膜电渗析可以利用氨基酸的等电点的不同而将它们进行分离。本论文共分为四章,内容分别如下:第一章为本论文的绪论部分,主要阐述了传统的有机酸的生产过程中存在的问题,接着对电渗析技术的基本原理,特别是作为整个电渗析技术核心的离子交换膜进行了较为详细介绍。最后对本论文的选题来源、意义及主要内容进行了简要的介绍;第二章首先通过相转化法制备出多孔的聚酰亚胺基膜,然后对该基膜进行化学改性,包括氨化、季铵化等,使膜接枝上正电基团,并通过场发射扫描电镜(SEM),傅里叶红外光谱分析(FTIR)表征确认其微观形态和组成。该膜的面电阻为0.6-1.8Ω·cm2,离子交换容量(IEC)值为0.6-0.9mmol/g,含水率为100-160%。不同条件下制备的膜的微观结构有所差异,在异丙醇中进行相转化得到的膜内部呈现出均匀的海绵状孔,而在水中进行相转化的膜内部出现了一些不规则的大孔,但总体上通过相转化法制得的膜具备有多孔的结构。将其应用于双极膜电渗析(BMED)过程处理乳糖酸钠料液以生产乳糖酸和氢氧化钠,与商业膜相比,产品纯度类似,能耗较低,产率更高,几乎达到了商业致密膜的两倍。第三章将BMED过程应用于苏氨酸和谷氨酸混合物的分离,首先,设计出三种不同的膜堆构型以优选出最佳的膜堆构型。然后在最佳的膜堆构型下,综合考虑混合氨基酸的分离效果、能耗、电流效率等因素,选取50V为最佳的外加操作电压。在优化的膜堆、电压条件下(电压为50V、膜堆构型为BP-A-BP),运行4 h后可以使料液室中的谷氨酸基本上迁移进入回收室,苏氨酸则停留在料液室中,其纯度达到了 97.5%。过程的能耗为11.04 kWh/kg,电流效率为82.6%。此外,还对实验过程的阴膜的污染进行了考察,发现有部分谷氨酸附着在阴膜上造成膜污染,导致了小部分的谷氨酸的损失,并使BMED的总体效能有所下降。总的来说,利用BMED过程进行苏氨酸与谷氨酸的分离提纯可以达到很好的分离效果。第四章为全文的总结部分,通过以上章节中所介绍的实验结果可以看出,利用BMED进行有机酸的生产,具有很好的潜力。
[Abstract]:Organic acid is an important industrial raw material in the process of industrial production. It is widely used in the industries of pharmaceutical, food and daily chemical production. The traditional methods of production include fermentation and chemical synthesis. The fermentation is a relatively mild way of production, which is used as renewable raw materials and sufficient sources. In contrast, chemical synthesis is of strong purpose and production conditions. The production and utilization of some organic acids is more difficult. Whether it is fermenting or chemical synthesis, the production process involves the separation and purification of the products, and often requires extraction, crystallization, distillation and other traditional chemical unit operations, which inevitably produce a large amount of pollutants in the process of separation and purification. High energy loss is difficult to meet the requirements of "green production" proposed by today's society. The new membrane separation technology, especially the electrodialysis technology, has been widely used in the production of small molecular organic acids, such as formic acid, acetic acid, citric acid, etc., but when the molecular weight of organic acids is large, the membrane technology is used for production. The efficiency will be greatly reduced because the resistance to membrane migration is large and it is difficult to achieve a higher yield. Therefore, we have proposed the preparation of a suitable pore size ion exchange membrane to improve the yield of organic acids and reduce the energy consumption of the process. In addition, amino acids are a special kind of organic acid, in the fields of medicine, food, animal feed and so on. The amino acid molecules also contain carboxyl and amino groups. The traditional separation methods, such as crystallization, ion exchange and special precipitation, are more complex. The evaporation energy in the crystallization process is very high. The resin needs more chemical reagents, and the precipitant in the special precipitation process is difficult to be recovered effectively, resulting in a large amount of waste liquid. Taking threonine as an example, the fermented mother liquid produced by the fermentation process of threonine contains a certain amount of threonine, glutamic acid and other impurities, and the bipolar membrane electrodialysis can be separated by the difference of the isoelectric points of amino acids. This paper is divided into four chapters, the contents are as follows: the first chapter is the thesis The introduction part mainly expounds the existing problems in the traditional organic acid production process, and then introduces the basic principles of electrodialysis technology, especially the ion exchange membrane, which is the core of the whole electrodialysis technology. Finally, the origin, significance and main contents of this paper are briefly introduced; second In this chapter, the porous polyimide basement membrane was prepared by phase transformation method. Then the membrane was chemically modified, including ammoniation, quaternification and so on. The membrane was grafted with positive group. The microstructure and composition of the membrane were identified by field emission scanning electron microscopy (SEM) and Fu Liye infrared spectroscopy (FTIR). The surface resistance of the film was 0.6-1.8 Omega cm2, The ion exchange capacity (IEC) value is 0.6-0.9mmol/g, and the microstructure of the membrane prepared under the water content is 100-160%. is different. The inner membrane of the isopropanol is transformed into a homogeneous sponge like hole, while some irregular large pores appear in the membrane of the phase transformation in the water, but in general the phase transformation is made by phase transformation. The prepared membrane has a porous structure. It is used in bipolar membrane electrodialysis (BMED) process to treat lactose acid and sodium hydroxide to produce lactose acid and sodium hydroxide. Compared with commercial membranes, the product has similar purity, low energy consumption, higher yield, almost two times the commercial density membrane. The third chapter applies the BMED process to threonine and glutamic acid. First, three different membrane heap configurations are designed to select the best membrane heap configurations. Then, under the optimum membrane configuration, the optimum external voltage is selected by considering the separation effect, energy consumption and current efficiency of the mixed amino acids. In the optimized membrane reactor, voltage condition (voltage is 50V, membrane structure). Type BP-A-BP), after running 4 h, the glutamic acid in the liquid chamber can be moved into the recovery room basically, and threonine stays in the liquid chamber. The energy consumption of the 97.5%. process is 11.04 kWh/kg and the current efficiency is 82.6%.. The membrane fouling caused the loss of a small portion of the glutamic acid and reduced the overall efficiency of BMED. In general, the separation and purification of threonine and glutamic acid by the BMED process can achieve a good separation effect. The fourth chapter is a summary of the full text, which can be seen through the experimental results introduced in the above chapters. The use of BMED for organic acid production has great potential.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ216;TQ028.8

【参考文献】