CS244591B1 - Xylanes preparation method from one year's plants - Google Patents

Abstract

The solution concerns the preparation of xylans of annual plants. The essence of the preparation lies in the fact that the lining material extracts 1 to 10% by weight. aqueous sodium hydroxide solution; \ tor. \ t 3 to 24 wt. aqueous hydroxide solution of potassium with an oxidizing additive reagents in an amount equivalent to 30% wt. active chlorine, related to vegetable material, at 25 to 80 ° C after for 1 to 6 hours and from an alkaline extract the xylans are isolated by precipitation in two to three times volume of alcohol; \ tand. \ t purify by washing with 70-85% vol. aqueous alcohol. As oxidative the reagent is an aqueous hypochlorite solution sodium or aqueous calcium hypochlorite solution. The solution is used in the pulp and paper industry, chemical, food, pharmaceutical and textile.

Description

(54) Method for preparing xylans from annual plants

2

The solution concerns how to prepare xylans from annual plants.

The essence of the preparation consists in extracting the overlay material from 1 to 10% by weight. % aqueous sodium hydroxide solution or 3 to 24 wt. aqueous potassium hydroxide solution with oxidizing agent added in an amount equivalent to 30% w / w. of active chlorine, based on plant material, at 25 to 80 ° C for 1 to 6 hours and from the alkaline extract, xylanes are isolated by precipitation in two to three times the volume of alcohol and purified by washing with 70 to 85% v / v. aqueous alcohol solution. As the oxidizing agent, an aqueous sodium hypochlorite solution or an aqueous calcium hypochlorite solution is used.

The solution is used in the pulp, paper, chemical, food, pharmaceutical and textile industries.

The invention relates to a process for preparing xylans from annual plants.

D-xylan-type heimicelluloses with varying levels of L-arabinose and uronic acids are present in the fiber parts of annual plants in an amount of 15 to 35%. These xylan sources are predominantly wastes arising from the processing of various cereals and other agricultural plants (straw, bran, maize grain husks, corn spindles, husks, sticks, etc.). The isolation of hemicelluloses from annual plants is dealt with by a variety of procedures involving a complex complex of operations such as treatment by extraction, enzyme treatment, delignification, multi-stage extraction and purification of isolated hemicelluloses [K. Wilkie C. B.: Adv. Carbohydrate Chem. Biochem. 36, 215 (1979J; US Pat No. 4181796; US Pat. 4,038,481; US Pat. No. 4,017,642],

The isolation of xylans by these processes is demanding not only for chemicals, but also for energy and technical equipment (freezing, electrodialysis, pressure swelling at high temperatures), which adversely affects the economics of the production process.

The above-mentioned disadvantages are substantially eliminated by the process of preparing xylans from the annual plants according to the invention, which consists in extracting the plant material from 1 to 10% by weight. % aqueous sodium hydroxide solution, or 3 to 24 wt. % aqueous potassium hydroxide solution with an oxidizing agent added in an amount equivalent to 0 to 30 wt. active chlorine, based on plant material. An aqueous sodium hypochlorite solution or an aqueous calcium hypochlorite solution at 25 to 80 ° C for 1 to 6 hours is used as the oxidizing agent. From the alkaline extract, xylanes are isolated by precipitation in two to three times the volume of alcohol and purified by washing with 70 to 85% v / v. aqueous alcohol solution.

The advantage of the proposed process for the preparation of xylans from annual plants over the known processes is that the present process is more economically efficient since high purity D-xylanes are isolated in one extraction stage in yields of 50 to 90% of the hemicelluloses present in the flood. The process is also less demanding on the chemicals used, time, energy and equipment. The extraction residue is a cellulosic material suitable for feeding or preparing feed biomass.

Example 1

A suspension of 1.1 kg of air-dried pulp of corn spindles in 7.5 l of 5 wt. of aqueous sodium hydroxide solution is stirred and heated to 40 ° C with stirring for 2 h. The extract is then filtered through a glass cloth and 7.5% of 5% by weight is added to the extract residue for washing. aqueous sodium hydroxide solution. The combined extracts precipitated to 30% by volume. ethanol. The rapidly sedimenting precipitate was recovered at 70% v / v after the second decantation. neutralized with a dilute acetic or sulfuric acid solution and further washed with 70 to 85 vol. recovered with ethyl alcohol until a colorless filtrate. After draining the xylan precipitate, 96% by volume. with ethyl alcohol, xylan was obtained in a yield of 30% (based on plant material) containing 93% by weight. xylose and arabinose at a molar ratio of 1: 0.1.

Example 2

The procedure is as in Example 1 except that 10 l of a 1% aqueous sodium hydroxide solution is added with the addition of 700 ml of a 15% aqueous sodium hypochlorite solution at 80 ° C for 1 h. 19% xylan is obtained with a content of 91% by weight. xylose and larabinose at a molar ratio of 1: 0.15.

Example 3

The procedure was as in Example 2 except that a 3% aqueous potassium hydroxide solution and 1.2 L of a 10 wt. aqueous calcium hypochlorite solution. The xylanes are precipitated in three times the volume of ethyl alcohol and washed with 85% by volume. ethanol. 16% xylan with 89% wt. xylose and arabinose at a molar ratio of 1: 0.2.

attaches

The procedure was as in Example 1 except that 15 l of a 24% by weight aqueous potassium hydroxide solution was used at 25 ° C for 6 h. This yields 26.5% xylan containing 90% xylose and arabinose in a molar ratio of 1: 0.2.

Example 1 and d 5

The procedure was as in Example 2 except that wheat straw and 15 l of 10% by weight were used. aqueous sodium hydroxide solution with the addition of 4.2 L of a 15% aqueous sodium hypochlorite solution at 40 ° C for 2 h. 30% xylan with 92% wt. xylose and arabinose at a molar ratio of 1: 0.19.

Xylanes are a type of plant polysadharides that are increasingly used in various areas of social practice. These polymers can be used in papermaking, in the food industry as neutral fillers in the preparation of low-calorie foods, in the chemical industry as raw materials for the production of D-xylose and xylite. Furthermore, xylanes and derivatives thereof are used as pharmaceuticals, detergents, flocculants and the like.

Claims (2)

SUBJECT Process for preparing xylans from annual plants, characterized in that the plant material is extracted with 1 to 10% by weight. % aqueous sodium hydroxide solution or 3 to 24 wt. % aqueous potassium hydroxide solution with an oxidizing agent added in an amount equivalent to 30 wt. of active chlorine, based on the plant material, at a temperature of 25 to 80 ° C OF THE INVENTION for 1 to 6 hours and from the alkaline extract, the xylanes are isolated by precipitation in two to three times the volume of alcohol and purified by washing with 70 to 85% v / v. aqueous alcohol solution. 2. The method of claim 1, wherein an aqueous sodium hypochlorite solution or an aqueous calcium hypochlorite solution is used as the oxidizing agent.