Vitamin C, also known as ascorbic acid, is a substance that cannot be synthesized by the human body but is necessary, and is closely related to human health. my country is a big producer of vitamin C. Among the 80,000 t/a vitamin C needed in the world, my country's supply reaches more than 50%. Vitamin C is a high-energy-consuming product. With the sharp drop in the price of vitamin C in the international market, the energy consumption in the production of vitamin C (especially the energy consumption in the purification and refining process of vitamin C, which accounts for 10% of the energy consumption in the entire production of vitamin C) should be reduced. More than 30%) has become the key to the survival of production enterprises.
Analysis of conventional vitamin C production and refining process
The current common methods for producing vitamin C are sulfuric acid acidification and ion exchange, among which sulfuric acid acidification has been basically eliminated, and ion exchange has become the main production process at present. Usually, the ion exchange process is to dissolve vitamin C sodium in water, and the solution passes through a cation exchange resin to remove sodium ions to form a vitamin C solution, which is concentrated under reduced pressure, cooled and crystallized, centrifuged to obtain crude vitamin C, and then refined and crystallized to obtain the finished vitamin Co cation The use of exchange resin will consume a large amount of tap water and discharge a large amount of waste acid and alkali, which will seriously pollute the environment and do not meet the requirements of clean production. At the same time, the concentration of vitamin C solution obtained by this separation method is low ( 15-20%), it needs a lot of evaporation and concentration to produce crude vitamin C, which makes the whole process cycle long, the product is easy to deteriorate, the crude vitamin C has poor quality, low yield, high energy consumption, large investment in equipment, and high cost .
Crystallization Filtration Washing Drying Four-in-one Refining and Purifying Vitamin C Process Design
The four-in-one process of crystallization, filtration, washing and drying for refining and purifying vitamin C is a new method for preparing high-purity vitamin C by using vitamin C sodium as raw material and using a fully automatic multi-functional filtering, washing and drying machine to overcome the shortcomings of the existing technology.
The specific process steps are:
(1) Acidification reaction step: According to the weight ratio of sodium vitamin C and water of 1:0.341 to 0.894, an aqueous solution of sodium vitamin C is made, and the aqueous solution of sodium vitamin C is added with hydrochloric acid or HCl gas under stirring, wherein VcNa:HCl is The pure weight ratio is 1:0.175~0.215, so that it can fully react to obtain an acid solution; add activated carbon to the obtained acid solution, the addition ratio is 1L of acid solution, add 2~10g of activated carbon, and then heat up to 65~70°C for decolorization and then keep warm Filtration produces a purified acid solution.
(2) Crystallization and separation step: cool down the acid solution after the acidification reaction while stirring, cool the acid solution to -5~5°C, and keep it for 1~3 hours to precipitate vitamin C from the acid solution, and filter to obtain crude vitamin C And the acid solution after vitamin C is precipitated;
(3) Desalting and filtering step: take the acid solution after crystallization and separation of crude vitamin C, concentrate under reduced pressure until the content of vitamin C is 50-60%, make vitamin C in a nearly saturated state at a temperature of 65-70°C, and control the temperature Insulate and filter at 65-70°C to remove sodium chloride to obtain a filtrate;
(4) Crude product crystallization and filtration step: wash the filtrate described in step 3 with ice water and ice methanol, then cool down to -5-5°C, and keep it for 2-10 hours, crystallize and filter to obtain the recovered crude product vitamin C; Vacuum suction filtration, the obtained crude product vitamin C and recovered product vitamin C.
(5) High-purity vitamin C refining steps: add crude vitamin C and recovered vitamin C to anhydrous salt water to dissolve, decolorize and filter, cool down, crystallize, separate, and dry to obtain finished vitamin C.
The high-purity vitamin C content is 99.8%, optical rotation = +21°, extinction value is 0.038, and other indicators are in line with the second standard of the Chinese Pharmacopoeia 2000 edition.
The process of crystallization, filtration, washing and drying four-in-one refining and purifying vitamin C utilizes the difference in the solubility of sodium chloride and vitamin C with temperature, acidifies sodium vitamin C directly with hydrochloric acid to generate an aqueous solution of vitamin C and sodium chloride, and uses hot filtration, cooling, Concentration method achieves gradual separation of vitamin C and sodium chloride, prepares crude vitamin C and by-product sodium chloride, and then refines and recrystallizes crude vitamin C to obtain finished vitamin C. All indicators of the finished product vitamin C are in line with the second standard of the Chinese Pharmacopoeia 2000 edition after inspection.
The new production process can greatly reduce water, acid and alkali, reduce energy consumption, solve environmental pollution, shorten production cycle, reduce production cost, improve product yield and product quality, and is an economical and effective vitamin C preparation method.