Application Research of Electrodialysis Technology in Amino Acid Purification and Desalination

Amino acids, as important bioactive substances, are widely used in pharmaceutical, food, feed and other fields. However, in the amino acid production process, salts are often introduced, leading to high salt content in the product, which affects its purity and application effect. As an efficient membrane separation technology, electrodialysis technology has shown unique advantages in amino acid purification and desalination. This paper introduces the principle of electrodialysis technology, its application status, advantages and challenges in amino acid purification and desalination, and prospects for future development directions.

1. Introduction

Amino acids are the basic units of proteins and have important physiological functions. In the production of amino acids, such as fermentation and hydrolysis methods, salts are often introduced, resulting in high salt content in the product. Amino acids with high salt content not only affect their physical and chemical properties such as solubility and stability, but also reduce their application effects in pharmaceutical, food and other fields. Therefore, purification and desalination of amino acids are key links to improve their quality.
Traditional amino acid desalination methods include ion exchange, solvent extraction, dialysis, etc., but these methods have problems such as high cost, low efficiency and environmental pollution. As a new type of membrane separation technology, electrodialysis technology has the advantages of low energy consumption, high efficiency and environmental protection, and has broad application prospects in amino acid purification and desalination.

2. Principle of Electrodialysis Technology

Electrodialysis technology uses the selective permeability of ion exchange membranes to move anions and cations in the solution toward the cathode and anode respectively under the action of a direct current electric field, so as to achieve ion separation and purification. In an electrodialysis device, multiple pairs of cation exchange membranes and anion exchange membranes are generally arranged alternately to form a set of freshwater chambers and concentrated water chambers. When a solution containing ions enters the freshwater chamber, under the action of an electric field, cations pass through the cation exchange membrane into the concentrated water chamber, and anions pass through the anion exchange membrane into the concentrated water chamber, thereby reducing the salt concentration in the freshwater chamber to achieve desalination; the concentrated water chamber discharges the aggregated ions.

3. Application Status of Electrodialysis in Amino Acid Purification and Desalination

3.1 Desalination of Single Amino Acids

Electrodialysis technology has achieved good results in the desalination of single amino acid solutions. For example, in the desalination of glutamic acid, electrodialysis technology can separate glutamic acid from ammonium chloride in the fermentation broth at the isoelectric point of pH=3.22 to achieve desalination. By optimizing the electrodialysis process conditions, such as electric field strength, membrane stack configuration, operation time and other parameters, high desalination rate and amino acid recovery rate can be achieved.

3.2 Desalination of Amino Acid Mother Liquor

High-salt mother liquor is produced in the amino acid production process, and traditional treatment processes have problems such as large consumption of acid and alkali, large resin loss, high production cost and environmental pollution. Electrodialysis technology can effectively solve these problems. For example, using electrodialysis technology to desalt amino acid mother liquor not only has low energy consumption, but also reduces the use and discharge of acid and alkali, and reduces environmental pollution. At the same time, electrodialysis technology can be perfectly combined with other processes such as ion exchange to further improve the desalination effect and product quality.

3.3 Separation and Purification of Pharmaceutical Amino Acid Compounds

Electrodialysis technology also plays an important role in the separation and purification of pharmaceutical amino acid compounds. For example, aiming at the problems of high energy consumption and large reagent consumption in the traditional separation process of stachydrine, a two-stage electrodialysis method is proposed to purify stachydrine from the brine eluate and recover NaCl; aiming at the long preparation process and tedious operation of potassium aspartate, an ion displacement reaction coupled with electrodialysis process is proposed to efficiently prepare potassium aspartate from ammonium aspartate in one step; aiming at the large consumption of ammonia water in the traditional preparation process of L-ornithine, a bipolar membrane water dissociation coupled with electrodialysis process is proposed to directly convert L-ornithine·HCl into L-ornithine. These applications show that electrodialysis technology has the advantages of high efficiency, low energy consumption and clean production in the separation and purification of pharmaceutical amino acid compounds.

4. Advantages of Electrodialysis in Amino Acid Purification and Desalination

4.1 High-efficiency Desalination

Electrodialysis technology can quickly and effectively remove salts from amino acid solutions and improve product purity. By optimizing the electrodialysis process conditions, high desalination rate and amino acid recovery rate can be achieved. For example, in the pilot and medium-scale tests of electrodialysis desalination of compound amino acids, the operating conditions of the medium-scale desalination process were successfully determined, and the effective separation of amino acids and salts was realized.

4.2 Environmental Protection and Energy Saving

Electrodialysis technology is a physical separation method that does not require the addition of chemical reagents and causes no pollution to the environment. At the same time, its energy consumption is relatively low. Compared with traditional evaporation and reverse osmosis technologies, electrodialysis has obvious energy consumption advantages. For example, using electrodialysis technology to desalt amino acid mother liquor can save more than 30% of energy consumption.

4.3 Continuous Production

Electrodialysis equipment can operate continuously. By controlling parameters such as feed flow rate and electric field strength, continuous desalination treatment of amino acid solutions can be realized, which helps to improve production efficiency and capacity to meet the needs of large-scale industrial production.

4.4 Simple Operation

Electrodialysis technology is relatively simple to operate, and the equipment maintenance cost is low. Compared with the ion exchange resin method, electrodialysis technology does not require frequent resin regeneration operations, reducing operation steps and labor costs.

5. Challenges Faced by Electrodialysis in Amino Acid Purification and Desalination

5.1 Membrane Fouling and Service Life

The complex components in the amino acid solution may cause pollution of the ion exchange membrane, affecting the efficiency of electrodialysis and the service life of the membrane. For example, macromolecules such as proteins and polypeptides may adsorb on the membrane surface, block the membrane pores, and reduce the permeability of the membrane. To alleviate this problem, it is necessary to optimize the membrane cleaning process and the selection of membrane materials, regularly clean the ion exchange membrane to remove pollutants on the membrane surface, and select membrane materials with good anti-fouling performance.

5.2 Co-ion Migration

In the electrodialysis process, in addition to the migration of target ions, co-ion migration may also occur, which reduces the desalination efficiency and affects the product quality. For example, in the amino acid desalination process, some ions with the same charge as amino acids may migrate together with amino acids, resulting in incomplete desalination. To reduce co-ion migration, it is necessary to optimize the electrodialysis process conditions, such as selecting appropriate membrane types and adjusting the electric field strength.

5.3 Cost Issues

Although electrodialysis technology has the advantages of low energy consumption and environmental protection, the equipment investment cost is relatively high. For some small enterprises, they may face financial pressure. In addition, the cost of membrane materials is also an important factor affecting the application of electrodialysis technology. To reduce costs, it is necessary to further develop high-performance and low-cost membrane materials and optimize the electrodialysis process to improve the operation efficiency of the equipment.

6. Conclusion and Prospect

Electrodialysis technology has the advantages of high efficiency, environmental protection, energy saving and simple operation in amino acid purification and desalination, and has achieved remarkable application results in desalination of single amino acids, desalination of amino acid mother liquor and separation and purification of pharmaceutical amino acid compounds. However, electrodialysis technology still faces problems such as membrane fouling and service life, co-ion migration and cost in amino acid purification and desalination.

 

In the future, with the continuous development of membrane material science and electrodialysis technology, these problems are expected to be solved. For example, developing ion exchange membranes with higher selectivity and better anti-fouling properties, optimizing electrodialysis process conditions, and improving desalination efficiency and membrane service life. At the same time, further reducing equipment investment and operation costs will help the wider application of electrodialysis technology in the field of amino acid purification and desalination, and promote the high-quality development of the amino acid industry.