Malic acid is an important organic acid, which is widely used in food, medicine, chemical industry and other fields. In the field of chemical production raw materials, malic acid manufacturing methods are mainly chemical synthesis and biological fermentation method. This article will introduce the specific steps, advantages and disadvantages and scope of application of these two manufacturing methods.
I. Chemical synthesis method
1. Lime method
Lime method is a commonly used malic acid manufacturing method, the principle is to use lime milk and sulfuric acid reaction to generate calcium sulfate and calcium bisulfate, and then add sodium carbonate or sodium bicarbonate to generate malic acid. The specific steps are as follows:
(1) Add the milk of lime to the sulfuric acid, control the pH between 2.5-3.5, and react to generate calcium sulfate and calcium hydrogen sulfate.
(2) Add sodium carbonate or sodium bicarbonate to the reaction solution to react with calcium bisulfate to form malic acid and sodium sulfate.
(3) Pure malic acid is obtained by centrifugal separation and crystallization steps.
The advantage of this method is that the process is simple and inexpensive, but the disadvantage is that a large amount of waste residue and waste water will be produced, which will cause pollution to the environment. Therefore, the method is gradually reduced in use in actual production.
2. Allyl Alcohol Method
Allyl Alcohol Method is a more advanced method of manufacturing malic acid, the principle is to use allyl alcohol with carbon monoxide, water and oxygen to carry out a gas-phase oxidation reaction to generate malic acid. The specific steps are as follows:
(1) Mix allyl alcohol, carbon monoxide, water and oxygen, and pass them into the reactor to carry out the gas phase oxidation reaction.
(2) The reaction product is cooled, absorbed and centrifuged to obtain malic acid solution.
(3) Pure malic acid is obtained by steps such as crystallization and drying.
The advantages of this method are higher yield and better product quality, while it does not produce a large amount of slag and wastewater. However, the method requires the use of precious metal catalysts, and the cost is high.
II. Bio-fermentation method
Bio-fermentation method is a method of producing malic acid using microbial fermentation. The specific steps are as follows:
(1) Add glucose, corn syrup and other nutrients into the fermenter and inoculate malic acid production strains.
(2) Under suitable temperature, pH and aeration conditions, the strains undergo a fermentation reaction to produce malic acid.
(3) Through centrifugal separation and filtration, malic acid solution is obtained.
(4) Through steps such as crystallization and drying, pure malic acid is obtained.
The advantage of this method is that the production process is more environmentally friendly and does not produce a large amount of waste residue and waste water. Meanwhile, the bio-fermentation method can utilize waste and agricultural by-products, etc. as raw materials and reduce the production cost. However, the production cycle of this method is long, and the fermentation conditions need to be controlled to improve the yield and purity of malic acid.
In summary, chemical synthesis method and biological fermentation method have their own advantages and disadvantages and scope of application. In actual production, the appropriate manufacturing method should be selected according to the specific situation in order to improve the yield and quality of malic acid, reduce the production cost, and protect the environment and human health at the same time.
