The method of microcrystalline cellulose

 

The invention concerns of microcrystalline cellulose and can be used, for example, in farmatsevticheskii, food, perfume and other branches of industry. Wood waste in the form of sawdust is treated with a mixture of 35% hydrogen peroxide and 30% acetic acid in the presence of sulfuric acid. Then carry out the solvolysis of the fibrous product. Wood waste is treated at a water ratio of 10-15:1, a temperature of 120-140oAnd duration 1-3 hours Technical result of the proposed method is an extension of the resource base, simplify the process, improve the quality of the target product, reducing its cost and improving the environmental friendliness of the process. 6 C.p. f-crystals, 2 tab.

The invention relates to the chemical processing of cellulose-containing raw material, particularly to a method of microcrystalline cellulose (MCC), which is widely used as filler in pharmaceutical, food and perfume industry, stabilizer, water and latex paints and emulsions, sorbents for chromatography. MCC can be used in medicine as a physiologically active substance, which improves the metabolic processes in the body.

what olaney, sulfuric, nitric and other) high-quality raw materials with low lignin content (cotton, Linter, cotton wool, cellulose, cotton waste and textile production). Low-grade raw materials (wood waste, sawdust) used only to obtain cellulose powder having a low quality due to high polymerization degree and a high content of residual lignin.

Thus, the known method for producing powder of cellulose, which consists in processing wood sawdust by boiling in hydrochloric or sulfuric acids in a mixture with an aqueous solution of nitrate salts of Na, K, NH4, Ni, Cu(II) or Cd at a volume ratio of solutions of acids and salts of 2.5-3.5:1, for 6-8 hours and the water ratio 20-30 (SU 1699142, 20.07.1989).

The disadvantages of this method are: ecologicall process that is caused by prolonged boiling of sawdust in such poisonous substances as hydrochloric or sulfuric acid, in the presence of alkaline salts and heavy metals, which are carcinogens; low quality product because of the high content of residual lignin (1.7 to 7.9%) and high average degree of polymerization (295-630); significant consumption of chemicals, which creates certain difficulties in the treatment of rinsing water from salts thee the vine, in which lignocellulosic material (wood chips) crushed explosive autohydrolysis followed by repeated extraction of lignin with water and solvent (0,41% NaOH, acetone, dioxane, ethanol and others). Next, the selected pulp is bleached with a solution of complex composition, followed by acid hydrolysis (SU 1792942, 07.02.1993).

The disadvantages of this method are its complexity and multi-stage, due to the requirement of special equipment for explosive autohydrolysis (operation is used for grinding lignocellulosic material), repeated and prolonged (24-hour) extraction, use of toxic solvents (acetone, dioxane). In addition, the disadvantage of this method is the application of bleach solution of complex composition, as well as the low quality of the resulting product.

Closest to the proposed method according to the physical entity and the final result is a method of microcrystalline cellulose by treatment of fibrous waste cotton and textile industry with a mixture of 3.5% hcl and 0.6% nitric acid in the presence of a catalyst 10% phosphorus molybdenum acid when heated to 80oC for 1 h quality raw materials with low lignin content (fibrous waste cotton and textile industry), low quality ICC because of the wide range of degree polimerizacii (150-400). The process can be complicated and environmentally unfriendly due to the use of environmentally hazardous mineral acids (hydrochloric, nitric, phosphoric and molybdenum); additional costs are required for their removal.

The invention aims: - the expansion of raw materials receiving MCC through the use of waste wood (sawdust); - simplification of the process of obtaining MCC; - improving the quality of the target product; - the reduction of its cost due to the use of wood waste and simplify the process; - improving the environmental friendliness of the process.

This objective is achieved in that in the method of microcrystalline cellulose by acid treatment of the cellulose-containing raw material according to the invention, is used as raw material wood waste (sawdust), which is treated with a mixture of 35% hydrogen peroxide and 30% acetic acid, taken in a molar ratio of 0.3-0.5, in the presence of sulfuric acid in the amount of 1.5-2.0% by weight of absolutely dry wood at a water ratio of 10-15: 1; the temperature of 120-140oWith and duration of 1-3 hours, followed by solvolysis of the fibrous product. The solvolysis is carried out in solution similar telesfora at a temperature of 110-130oWith the water ratio of 10-15: 1 and duration of 1-2 hours. As wood waste use sawdust birch, fir, larch.

Comparative analysis of the proposed method with the prototype shows that the invention allows to significantly expand the resource base of the receipt of the ICC, and therefore, to dispose of huge reserves of wood waste lesopererabatyvayuscij industry.

The use of delignification processes (treatment with hydrogen peroxide and acetic acid in the presence of sulfuric acid as catalyst and subsequent solvolysis allows to obtain microcrystalline cellulose of higher quality: Kr=0,66-0,74, SP=100-248 (in the prototype 150-400). The proposed method allows to reduce the cost of the obtained MCC through the use of cheap raw materials. Replacement of environmentally harmful mineral acids (in the prototype) on hydrogen peroxide and acetic acid makes the process more environmentally friendly.

The proposed method is confirmed by specific examples.

Example 1. 10 g of sawdust aspen faction 2 mm<d<5 mm with lignin 21,8%, dried at a temperature of 105oC to constant weight, placed in a reactor, add 27 ml of hydrogen peroxide, 123 ml in the s (2 wt.% from the absolutely dry wood). The water ratio is 15:1. The reactor is placed in a heat chamber and maintained at a temperature of 120oC for 2 hours. After which the mixture is cooled, filtered, separating the solution from the fibrous product and washed with water until neutral. The washed product is subjected to solvolysis in water ratio of 15:1 in a mixed solution containing hydrogen peroxide and an aqueous solution of acetic acid (the molar ratio of N2O2/CH3COOH=0.5), and the temperature of the 120oC and a duration of 1 hour. Then the obtained product is separated from the solution by filtration, washed with water until neutral and dried at a temperature of 105oC to constant weight. The output ICC 3,05 g (30.5% of the mass of absolutely dry wood or 90,9% of the mass of absolutely dry fibrous product). The degree of polymerization (SP) 217.

Examples 2-17. Perform analogously to example 1, but varying the composition of the working solutions.

The main characteristics of microcrystalline cellulose obtained from wood waste are shown in table 2. Indicators of quality of MCC are the degree of polymerization (SP), the crystallinity index (CI), the crystallite size along the normal to the plane (002).

Thus, the proposed method for microcrystallite isit quality of the target product; to simplify the process of obtaining MCC; - to reduce its cost due to the use of wood waste and simplify the process;
- to improve the sustainability of the process.


Claims

1. The method of microcrystalline cellulose by acid treatment of the cellulose-containing raw material, characterized in that is used as raw material wood waste, which is treated with a mixture of 35% hydrogen peroxide and 30% acetic acid in the presence of sulfuric acid with subsequent solvolysis of the fibrous product.

2. The method according to p. 1, characterized in that the wood waste is treated at a molar ratio of hydrogen peroxide and acetic acid 0.3 to 0.5.

3. The method according to p. 1, characterized in that the wood waste is treated in the presence of sulfuric acid in the amount of 1.5-2.0% by weight of absolutely dry wood.

4. The method according to p. 1, characterized in that the wood waste is treated at a water ratio of 10-15: 1, a temperature of 120-140oAnd duration 1-3 hours

5. The method according to p. 1, characterized in that the solvolysis of the fibrous product is carried out in a mixture of 35% hydrogen peroxide and 30% acetic acid at a molar ratio of 0.3-0.5.

6. The method according to p. 1, autocatalytically 1-2 hours

7. The method according to p. 1, characterized in that as wood waste use sawdust birch, fir, larch.

 

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