Electrodialysis Empowering Methionine Production: Application Paths and Practical Exploration

Methionine, also known as methionine, is the only non-polar α -amino acid containing sulfur. It is widely used in fields such as medical nutrition products, food additives and feed additives. At present, the global annual production capacity of methionine is approximately 1 million tons, and the annual output is about 700,000 tons. However, the traditional methionine production process has many shortcomings, such as high energy consumption, high pollution and low efficiency. To overcome these challenges, researchers have been constantly exploring new production processes, among which electrodialysis technology has attracted much attention due to its high efficiency and environmental friendliness.

I. Traditional production process of Methionine
The traditional production of methionine mainly adopts the sulfuric acid acidification method. This method consumes a large amount of sulfuric acid during the acidification process and generates a large amount of sodium sulfate as a by-product. The extraction and refinement process is lengthy, labor-intensive, costly in production, and generates a large amount of high-salt wastewater. At present, the commercial production of methionine mostly adopts the acrolein method in chemical synthesis, but this method also has problems such as high energy consumption and low conversion rate.

Ii. Introduction to Bipolar Membrane Electrodialysis Technology
Bipolar membranes are a type of ion-exchange membrane with special functions. Under the influence of an electric field, the intermediate layer undergoes water dissociation, generating H+ and OH- ions. Bipolar membrane electrodialysis technology integrates this special function into ordinary electrodialysis, enabling immediate acid/alkali production/regeneration, or acidification and/or alkalization. This technology has been applied in inorganic processes, such as the preparation of corresponding acids and bases from salt solutions or waste liquids like NaCl and Na2SO4.

Iii. Application of Bipolar Membrane Electrodialysis in Methionine Production
In recent years, researchers have applied bipolar membrane electrodialysis technology to the production process of methionine and achieved remarkable results. The specific process is as follows:

Preparation of hydrolysate: Dilute the hydrolysate of methyl thio-ethyl propionyl gland (hydantoin) 3 to 5 times to obtain an aqueous solution of sodium methionine and sodium carbonate.

Filtration treatment: The diluted hydrolyzed product is filtered through a microporous filter to remove impurities.

Electrodialysis treatment: The filtered hydrolysate is pumped into either the salt chamber or the salt/acid chamber of the bipolar membrane electrodialysis device. Inject electrolyte solutions of a certain concentration into other compartments. Connect the cathode and anode of the device to the negative and positive terminals of the DC power supply respectively, start the bipolar membrane electrodialysis device, and control the current density of the DC electric field to be 50-150mA/cm², and the temperature to be between 20 and 40℃

Product collection: In the acid chamber, high-purity methionine can be obtained, with a methionine recovery rate of over 95% and a current efficiency of approximately 70%. Meanwhile, sodium hydroxide with a concentration of 4 to 6% is obtained in the alkali chamber. In addition, carbon dioxide can also be collected to achieve carbon capture.

Iv. Advantages of Bipolar Membrane Electrodialysis Technology
Compared with the traditional methionine production process, the bipolar membrane electrodialysis technology has the following advantages:

High yield: By using bipolar membrane electrodialysis technology to prepare methionine, the yield is significantly increased, and the product quality is stable.

Pollution-free: This process does not generate a large amount of high-salt wastewater during production, reducing environmental pollution.

Less raw material usage: By optimizing process conditions, the consumption of raw materials can be reduced, and production costs can be lowered.

Carbon capture: By taking advantage of the property of amino acid salts to capture carbon dioxide and convert it into the corresponding neutral amino acids, carbon capture and reuse are achieved, which is in line with the production concept of low-carbon and environmental protection.

The application of bipolar membrane electrodialysis technology in methionine production has brought revolutionary changes to traditional processes. It not only increases the yield and quality of methionine, but also reduces production costs and environmental pollution. In the future, with the continuous advancement of technology and the continuous optimization of processes, the application prospects of bipolar membrane electrodialysis technology in methionine production will be even broader. Meanwhile, this technology can also be extended to the production fields of other amino acids, contributing to the green development of the chemical industry.