电渗析脱盐在提取发酵液中谷氨酰胺的应用研究

提出了电渗析脱盐与单阴离子交换柱相耦合提取发酵液中谷氨酰胺的分离工艺。研究发现,将发酵液pH调节到谷氨酰胺等电点附近,通过电渗析将其中的无机盐脱除95％左右时,仍然能保证谷氨酰胺收率达到76％,电流效率为85％。根据谷氨酰胺和谷氨酸等电点差异,电渗析脱盐后的料液再通过单根阴离子树脂交换柱,可以去除其中的谷氨酸等杂质。该工艺大幅度地减少了树脂用量,有效地解决了谷氨酰胺在强碱和强酸环境中的转化问题,生产成本明显降低,谷氨酰胺的总提取收率达到60％左右,且产品纯度符合药典。     

Removal of hardness in fermentation broth by electrodialysis

Lysine fermentation broth was desalinated by electrodialysis to reduce hardness concentrations as a pretreatment procedure for the purification and recovery of amino acids. Electrodialysis performance was investigated in terms of the rate of reduction in conductivity in dilute solutions and electrodialysis cell resistance for different ion exchange membranes at a constant current density. Among the membranes investigated in this study, membranes with high water content showed the better performance for hardness removal. Fouling experiments revealed that organics gave rise to fouling effects on the anion exchange membrane during demineralization of the lysine fermentation broth. The pulsed electric field with the half‐wave power enhanced the electrodialysis performances by mitigating membrane fouling in desalination of the lysine fermentation broth. This study successfully demonstrated the potential use of pulse power as an effective cleaning‐in‐place (CIP) method during electrodialysis of fermentation broth. © 2002 Society of Chemical Industry     

乳酸发酵液电渗析过程中氨基酸的迁移现象

使用三室双极膜电渗析法处理乳酸发酵液时,杂质氨基酸的迁移会影响回收乳酸的纯度. 通过对乳酸发酵液电渗析过程中氨基酸迁移现象的研究,发现各种不同氨基酸的迁移速率主要受其初始浓度、pI值与料室pH值的差值、阴离子交换膜对其选择性及其自身电迁移率的影响. 根据此规律,建立了离子迁移速率计算模型,通过与实际过程比较,表明其可有效预测杂质氨基酸的迁移情况,估算特定体系达到预定收率时的纯度. 实验验证结果表明,氨基酸的迁移率为32.5%,与对照实验(82.6%)相比,降低率为60.7%. 通过调节氢渗漏控制料室pH值、提高阴膜对乳酸的专一选择性等可控制氨基酸向酸室迁移,以获取更高的乳酸纯度.     

用电渗析法从谷氨酰胺模拟发酵液中脱除谷氨酸

为改进微生物发酵法生产谷氨酰胺的流程,提出用电渗析方法来分离谷氨酰胺和谷氨酸。在对混合氨基酸溶液中离子成分进行分析的基础上,预测了此方法的可行性,并通过电渗析方法对模拟发酵液进行实验来验证此预测结果。还考察了在混合物中含有硫酸铵时的情况。通过理论预测和实验验证,可以用电渗析法直接分离谷氨酰胺和谷氨酸,且原料中少量的硫酸铵有利于分离过程的进行。     

发酵液中乳酸的电渗析法分离

采用电渗法分离发酵液中低浓度乳酸,考察了电渗析器的操作条件对极限电流密度和乳酸电年速率的影响,并分别用修正的Ｗｉｌｓｏｎ公式和乳酸电渗析速率方程描述了它们之间的关系。     

Sodium hydroxide and hydrochloric acid generation from sodium chloride and rock salt by electro-electrodialysis

An electro-electrodialysis process (EED) is used to generate HCl and NaOH from trade NaCl. The key phenomenon limiting the current efficiency of this process is proton leakage through the anion selective membrane. Two new low proton leakage membranes: the ARA and ACM were used. NaOH and HCl solutions with purity higher than 99.9% are obtained. The experimental values of the fluxes for HCl and NaOH are compared with values calculated from integration of the Nernst–Planck electrodiffusion equations. This calculation requires several experimentally determined parameters: ionic diffusion coefficients, membrane conductance and amount of sorbed electrolyte. Algerian rock salt from El Outaya is used to compare electro-electrodialysis and electrodialysis using bipolar membranes.     

电驱动膜过程在氨基酸发酵液处理中的研究进展

在发酵法生产氨基酸的过程中,需要后续工艺对发酵液进行分离纯化以提取目标产物.电驱动膜过程正逐渐成为该领域研究与应用的热点.本文介绍了近年来国内外普通电渗析(ED)、双极膜电渗析(BMED)、离子取代电渗析(ISED)、电复分解反应器(BMT)等常见的电驱动膜过程在氨基酸发酵液处理中的研究进展,简述了常见的膜堆构型及其工作原理、特点与应用实例.分析表明电驱动膜过程可以实现混合氨基酸分离、无机盐脱除以及氨基酸的制备,膜堆结构、操作参数的优化以及新型分离膜的研究与应用可以提高过程性能.同时也指出目前该领域的研究尚处于实验室研究阶段,研究对象以模拟发酵液为主,规模化应用的报道还不多见.但是可以预见高效、环保的电驱动膜过程将会在氨基酸发酵液处理中发挥重要作用.     

Studies on transport properties of short chain aliphatic carboxylicacids in electrodialytic separation

An electrodialysis process was employed to investigate the concentration of formic, acetic and propionic acid solutions under different experimental conditions. In this process interpolymer-type ion-exchange membranes were used due their high chemical stability and durability. The effects of concentration, electric current and time on the electrodialysis process were studied. A mathematical equation representing the water transport behavior of the electrodialysis process for concentrating acids under the influence of different current densities was developed. This equation is valid for any electrodialysis process with ion-exchange membranes used under similar operating conditions. The reliability of the water transport equation was tested through comparison with the experimental data. Results indicate that electrodialysis is an effective method for concentrating shorter chain aliphatic carboxylic acid solutions. Ionic transportation, power consumption and current efficiency data reveal the following trend of the electrodialysis process's efficiency during concentration of carboxylic acid solutions: formic acid > acetic acid > propionic acid.     

Recovery of alpha-ketoglutaric acid from model fermentation broth using electrodialysis with bipolar membrane

ABSTRACT

A bipolar (BP) membrane electrodialysis (EDBM) was used to recover the alpha-ketoglutaric acid (AKG) from the model broth. A two-chamber EDBM membrane stack consisting of an anion exchange membrane and a BP membrane was used. The effect of the initial composition, applied current density, and pH of diluate on the efficiency of EDBM processes was investigated. The obtained results showed that the used membrane stack configuration allows complete separation of AKG from glucose and ethanol and simultaneous conversion of AKG salts to the acidic form. The scale-up of the EDBM process for model fermentation broth was also carried out.     

Lactic acid production by electrodialysis Part II: Modelling

One interesting alternative to the usual end-of-pipe processes for treating waste water produced during cheese-making involves its fermentation to sodium lactate. Then, electrodialysis can be used to recover free lactic acid from the fermentation broth. The design and optimization of such a process is aided by a suitable mathematical model. This work presents a model of the performance of an electrodialysis stack to be used in such a process. Its reliability has been assessed by comparison with experimental data for free lactic acid recovery from sodium lactate solutions. A suitable procedure for estimating some process-dependent parameters is also discussed.     

电渗析在发酵法制有机酸中的应用

介绍了电渗析的基本原理及电渗析器的结构类型，综述了电渗析在有机酸提取中的应用以及有机酸发酵与电渗析分离耦合的研究进展。     

Mathematical Modeling of Electrodialysis Demineralization Using a Stochastic Model

A stochastic model is proposed to calculate efficiency indices for the treatment of liquid mixtures by electrodialysis using methods of queuing theory. Electrodialysis demineralization of an ammonium sulfate solution is experimentally studied. Comparison between the experimental and theoretical data confirms the validity of the model.__________Translated from Teoreticheskie Osnovy Khimicheskoi Tekhnologii, Vol. 39, No. 3, 2005, pp. 278–281.Original Russian Text Copyright © 2005 by Yustratov, Pavskii, Krasnova, Ivanova.     

Downstream Processing of Lactic Acid by Membrane-Based Solvent Extraction∗

Abstract

Lactic acid has extensive use in the food and chemical industry. About half the lactic acid used in the world is produced by fermentation of carbohydrates using lactic acid bacteria. The recovery of lactic acid from the fermentation broth is more difficult than the fermentation itself. In the present work a study of membrane-based solvent extraction as a separation unit for the continuous downstream processing of lactic acid from fermentation broth was carried out. The experiments were performed using simulated fermentation broths made of lactic acid in acetate buffer or distilled water as the feed solution. The effects of membrane material, organic carrier, and pH of the feed solution on membrane extraction efficiency were investigated. A separation degree of 35% was obtained by using a polyether-etherketone (PEEK-WC 14%) membrane with 5% trioctylamine as the organic carrier in n-heptane. The experimental results obtained with the simulated system encourage the use of membrane-based solvent extraction with a real fermentation broth.

     

Relation between mass transfer and operation parameters in the electrodialysis recovery of acetic acid

The recovery of acetic acid from dilute wastewater by means of bipolar membrane electrodialysis is studied in more detail. The current efficiency of the electrodialysis recovery of acetic acid from dilute wastewater is related to the current density and other operation parameters. There exists a highest value of current efficiency at optimal current density. The highest concentration of recovered acid is also related to current efficiency. The experimental data are analyzed on a theoretical basis.     

Evaluation of recovery characteristic of acidic and alkaline solutions from NaNO3 using conventional electrodialysis and electrodialysis with bipolar membranes

We compared the electrodialysis performance for HNO₃ and NaOH recovery from NaNO₃ solution by conventional electrodialysis (ED) and electrodialysis with bipolar membranes (EDBM) at constant current and constant voltage. The individual resistances of the components of the electrodialysis systems were also evaluated. The electrodialysis extent for HNO₃ and NaOH recovery from NaNO₃ solution was almost proportional to the total amount of electricity supplied to the system, regardless of the operation mode and the electrodialysis systems. For the same volume of feed solution, the energy consumption and current efficiency differed depending on the operation mode and the electrodialysis system. In both the ED and EDBM systems, the conductivity of the feed solution strongly affected the overall cell resistance after approximately 50% of the ions in the feed solution had migrated.     

扩散渗析-电渗析回收赖氨酸离子交换废液中的盐

为缓解电渗析膜污染,提高电渗析性能,采用阴膜扩散渗析对待脱盐的赖氨酸离子交换废液进行净化处理,对扩散渗析回收的(NH4)2SO4溶液进行电渗析脱盐浓缩。结果表明,当扩散渗析流量为5.6 L/h时,扩散渗析的扩散系数达2.24?10?7 cm2/s,离子交换废液中(NH4)2SO4透过率约为30%,可截留90.1% Mg2+和94.5%有机氮、80.3%蛋白、86.0%总糖、79.3%化学需氧量(COD);与直接电渗析赖氨酸离子交换废液相比,对扩散渗析回收的(NH4)2SO4溶液进行电渗析脱盐浓缩,SO42?膜通量、电流效率分别提高了55.7%和18.3%,操作时间、单位膜通量能耗分别降低了26.1%和42.3%。用扩散渗析净化赖氨酸离子交换废液可有效缓解后续电渗析的膜污染,提高电渗析性能。     

1,3 丙二醇发酵液电渗析法脱盐

对1,3 丙二醇发酵液电渗析法脱盐的工艺进行了初步研究,主要就发酵液电导率与温度的关系、膜对电压、发酵液过滤与絮凝预处理、发酵液初始pH对脱盐效果的影响及膜的重复使用性进行了研究. 结果表明,发酵液电导率与温度呈线性关系,电导率温度校正系数为0.0217;膜对电压1.3~1.5 V为较适操作电压;脱盐过程耗时越长,1,3 丙二醇的损失越大;发酵液通过壳聚糖絮凝预处理后可以明显改善脱盐效果;发酵液pH对脱盐有明显影响,pH越低脱盐速率越快,膜连续重复使用15批次后性能下降明显,需要用NaOH和NaCl溶液进行清洗.     

模拟移动床连续离子交换法提取L-谷氨酰胺的工艺研究

L-谷氨酰胺是人体必需氨基酸之一，在医药食品等领域有着广泛的应用。目前，发酵法生产L-谷氨酰胺的提取工艺采用的离子交换方法树脂利用率低，生产周期长，酸碱用量大。模拟移动床（Simulated Moving Bed）连续离子交换技术是一种先进高效的分离方法，采用此方法分离提纯谷氨酰胺发酵液将产生极大的经济效益和社会效益。     

Lactic acid production by electrodialysis Part I: Experimental tests

Lactic acid, the production of which from cheap raw materials is attractive due to its great potential in the production of biodegradable polymers, can be obtained from fermentation broths using electrodialysis. This work discusses the feasibility of this process using commercial membranes, together with the influence of several operating parameters on the electrodialysis stack performance. It was found that it is possible to operate with high current efficiency values, while the overall recovery of sodium lactate depends on the current density. Electroosmotic water transport limits the maximum concentration value achievable using this technique.