Are you looking for Sodium Carboxymethyl Cellulose Formula? Congratulations, you’ve come to the right place. I have sorted out seven production methods of sodium carboxymethyl cellulose. I hope this article is helpful to you.
Before that, you probably already know what sodium carboxymethyl cellulose is. But I have to say it again.
Sodium carboxymethyl cellulose (CMC-Na) is an organic compound with the chemical formula of [C6H7O2(OH)2OCH2COONa]n. It is a carboxymethylated derivative of cellulose and the most important ionic cellulose gum. Sodium carboxymethyl cellulose is an anionic macromolecular compound usually prepared by the reaction of natural cellulose with caustic soda and monochloroacetic acid. The molecular weight ranges from thousands to millions. CMC-Na is white fibrous or granular powder, odorless, tasteless, hygroscopic, and easy to disperse in water to form a transparent colloidal solution.
Here are seven ways to make sodium carboxymethyl cellulose. This may give you some ideas for the sodium carboxymethyl cellulose formula you are looking for. Let’s get started.
1. Carboxymethyl cellulose is produced by reacting cellulose with sodium hydroxide to produce alkali cellulose. And then carry out carboxymethylation with monochloroacetic acid. The preparation method can be divided into an aqueous medium method and a solvent method. The aqueous medium method uses water as the medium for the reaction. In the solvent method, the reaction is carried out in solvents such as isopropanol, ethanol and acetone.
2. Refined cotton, caustic soda, alcohol mixed solution and chloroacetic acid alcohol solution are added into a kneader for alkalization and etherification. Neutralizing with hydrochloric acid, washing with alcohol, drying, and pulverizing to obtain the product.
3. Refined cotton is usually used as raw material to react with sodium hydroxide to produce alkali cellulose, which is then hydroxymethylated with acetic acid.
4. Stacking with rice straw and corn husk as raw material
And that straw, the corn husk and other plant straws are store outdoors under natural conditions. It can be carried out all the year round for more than 6 months, and attention should be paid to fire prevention, moisture prevention and mildew prevention during storage.
The stored straws are washed to swell and remove impurities, dust, etc. The mass ratio of the water to the raw materials is 1:3.
The pretreated straw is cut into slices for pre-soaking and cooking. The length of the grass piece can be determined according to the size of the container, and is generally about 10 mm.
The cut grass slices are put into an iron pot or a jar for pre-soaking. The solution for preimpregnation can be the waste liquor from the previous pot of cooking at a temperature of 18 ~ 25 ℃ for about 2 H. The ratio of the waste liquid to the raw material is 1:3.
Putting the pre-soaked grass slices into a cooking pot, and cooking the grass slices with sodium hydroxide solution. The content of sodium hydroxide is 5% -10%. The cooking time is 3 ~ 5 H, the temperature is 80 ~ 100 ℃, and the ratio of alkali liquor to raw material is 1 ∶ 3.
This process is carried out in a beater, the purpose of which is to break up the fibers and turn them into cellulose.
The washed straw fiber is bleached by sodium hypochlorite (the content is 15% to 20%) or bleaching powder (the content is 30% to 33%). And then dry in an oven. The moisture content of the dried straw should be about 10%, the drying temperature should be 30 ~ 50 ℃, and the drying time should be about 1 H.
Carrying out alkalization treatment on the dried straw cellulose in a sodium hydroxide solution with the content of 17.5 to 22%. Nerating alkalized cellulose. Alkalization is carried out in a mixer for 50 to 60 minutes at a temperature of less than 40 deg C. The alkali fib is etherified by chloroacetic acid with that content of 10 to 13%. Producing crude sodium carboxymethyl cellulose. Etherification and alkalization were carried out in the same mixer, that is, etherification was carried out immediately after alkalization for 50 ~ 60 min.
The etherification time is 45 to 50 minutes and the temperature is 74 to 78 deg C. Centrifugally pumping the etherified crude sodium carboxymethyl cellulose into a washing tank by a thick slurry pump. And was with 85% alcohol and hydrochloric acid (with that content of more than 18%) for 20 to 30 minutes to obtain pure sodium carboxymethyl cellulose.
The washed sodium carboxymethyl cellulose was dried to make its water content less than 15%, the drying time was about 3 H, and the temperature was controlled at about 100 ℃. Crushing the refined sodium carboxymethyl cellulose by a hammer crusher, and finally packaging.
5. (1) Soak the degreased and bleached cotton thread in 35% concentrated alkali solution for about 30 minutes and take it out. The liquid alkali can be recycled. The soaked cotton fiber is weighed on a flat squeezer, and the alkali liquor is squeezed out under the pressure of 14MPa to obtain the alkalized cotton.
(2) Put the alkalized cotton into the etherification kettle, add 15 parts of alcohol, slowly add chloroacetic acid alcohol solution with stirring, and complete the etherification at 30 ℃ within 2 H. After the addition is finished, the etherified cotton is obtained by stirring for 3 hours at 40 deg C. 120 parts of alcohol (70%) were added into the etherified cotton and stirred for 0.5 H. Add hydrochloric acid to adjust the pH to 7. Washing with alcohol twice, filtering to remove alcohol, drying at 80 ° C, and pulverizing to obtain the final product.
The products with low degree of substitution (less than 0.4) and medium degree of substitution (0.4 to 1.2) can be produced according to different ingredient ratios.
6. Method for refining sodium carboxymethyl cellulose.
In the preparation of sodium carboxymethyl cellulose, besides the main products, a large number of by-products such as sodium chloride, sodium glycolate and a small amount of sodium carbonate are also produced. The amount of sodium carboxymethyl cellulose produced varies depending on the preparation method used. Generally between 50% and 70%. In order to obtain sodium carboxymethyl cellulose with higher purity, such as sodium carboxymethyl cellulose for food and medicine, it must be refined. \n There are two main refining methods, namely sulfuric acid method and methanol method.
6.1 Sulfuric acid method.
Impregnating the crude sodium carboxymethyl cellulose with 15% -20% sulfuric acid. The -CH2OCH2COONa in the sodium carboxymethyl cellulose is converted into -CH2OCH2COoh, namely CMC acid. It is insoluble in water, so it can be washed with large amounts of water to remove glycolic acid, NaCL, sodium sulfate and sulfuric acid. And then perform centrifugal separation and drying to obtain that pure sodium carboxymethyl cellulose.
6.2 Methanol method.
The crude sodium carboxymethylcellulose is washed several times with 65% -85% methanol aqueous solution to remove impurities such as sodium chloride, sodium glycolate, sodium carbonate and the like, thereby obtaining pure sodium carboxymethylcellulose.
Because cellulose and alkali cellulose are insoluble in water, the reaction is carried out in a heterogeneous system when water is used as the reaction medium, and the reaction process is complex. In production, in order to obtain a more uniform product, the reaction conditions are selected and controlled mainly from two aspects of increasing the diffusion rate and reducing the chemical reaction rate.
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Sodium Carboxymethyl Cellulose Formula