D-mannitol is a slightly sweet colorless or white crystalline powder similar to sucrose. It has a certain role in medicine, food, feed, and life science research.
The preparation method of D-mannitol:

1. D-mannitol can be extracted from kelp or seaweed, but electrolytic reduction or catalytic reduction of glucose or sucrose solution is often used. The following is a brief introduction.
(1) Method of extracting from kelp
Soak the dried kelp in an appropriate amount of water at room temperature to swell, and stir continuously to dissolve the mannitol into the water. Adjust the pH value of the washing liquid to 12 or more with caustic soda to make it precipitate more than 16H. Then use 1:1 sulfuric acid to adjust the pH value to be neutral, evaporate and concentrate to a relative density of 1.30 to 1.32 and then cool down, the supernatant liquid is evaporated and concentrated to a relative density of 1.42 to 1.45, and the concentrated solution is cooled by thermocentrifugation to remove salt. Crystallize and centrifuge to obtain crude mannitol. The crude product was recrystallized with boiling water, decolorized with activated carbon, eluted with alcohol for chloride ion, and dried to obtain pure mannitol.
(2) Electrolytic reduction method
Glucose or sucrose is used as raw material to prepare a solution of suitable concentration, and the pH value is adjusted with sodium sulfate to 7.0, and then added to the electrolytic cell for electrolysis. The electrolyte solution is decolorized by activated carbon, vacuum concentrated, ethanol desalted, crystallized by cooling and centrifuged to obtain crude mannitol. The D-mannitol manufacturer tells you that the crude mannitol is recrystallized to obtain a fine product.
(3) Catalytic reduction method
The catalytic reduction method is to hydrolyze, neutralize, and catalytically hydrogenate the sucrose solution to obtain crude sorbitol and mannitol solutions, and then filter, decolorize with activated carbon, ion exchange, concentrate, crystallize, and separate to obtain fine mannitol. .
2. Fermentation method of Aspergillus oryzae.
3. Reduction method
The D-mannitol manufacturer tells you that the glucose and fructose generated by the hydrolysis of sucrose are then reduced to a mixture of sorbitol and mannitol, and then decolorized, separated and purified to obtain mannitol.