CS205972B1 - Method of preparation of the netted powder holocellulose - Google Patents

Description

The invention aa relates to the cross-linking of a novel starting material - wood sawdust holocellulose - for the preparation of polysaccharide ion exchangers.

There are known methods of cross-linking various polysaccharide materials: microcrystalline cellulose (US Pat. 136062), starch (Can. Pat. 960652), pectins (US Pat. 140713), amylose (B. Pfannemuller, Lu Sperlich, Makromol. Chem. 1978, p. 1965), hemicellulose (U.S. Pat. No. 161464, NSR-Offen. 1924000), and semi-cellulose (U.S. Pat. No. 1,662,333).

The starting holocellulose can be prepared by various procedures for the delignification of wood sawdust, which are accompanied only by slight degradation and atrophy of the polysaccharide components of cellulose and hemicellulose (Timell, T. B., Adv. Carbohydr. Chem. 19, 296-1964).

SUMMARY OF THE INVENTION The holocellulose of sorted wood sawdust aa after alkalinization in an emulsion of 25-30% sodium hydroxide and isopropyl alcohol at 20-25 ° C after 1 hour filtered or centrifuged to a weight of 200-250% of its initial weight. The alkaline holocellulose is transferred to a mixing and heating vessel and crosslinked by adding 0.5 to 1 mole of crosslinker, preferably epichlorohydrin, at a temperature of 50 to 60 ° C for 1 to 2 hours. After washing the crosslinked product with water until neutral and displacing the water with ethanol or acetone, it is freely dried at room temperature. A weight gain of 20 to 30% is obtained, wherein the crosslinked product has a solubility in diluted alkali of up to 5% ·

The advantage of the proposed method for the preparation of cross-linked holocellulose wood sawdust is that:

205 972

i.

205 972

- does not require pulp production, resp. microcrystalline cellulose,

- it has a corpuscular character in comparison to filamentous solids, as it retains the shape of sawdust, the size of which can and can be varied by suitable sawdust of wood sawdust,

- economically utilizes wood raw material because, in addition to the cellulosic component, hemucelluloses, which account for approximately 1/3 of the wood mass and form soluble waste in the pulp production, are cross-linked,

- sawdust of various woods or mixtures thereof may be used as raw material,

- the crosslinked product is stele within a certain pH range, allowing its use as a starting material for the preparation of ion exchangers,

- the sodium hydroxide emulsion in isopropyl alcohol can be reused for alkalization after alkalinity treatment.

Example 1 kg of air-dry holocellulose of sorted beech sawdust (particle size 0.1 to 3 mm and lignin content up to 5%). The mixture is stirred into an emulsion of 10 l of isopropyl alcohol and 1.0 l of 30% sodium hydroxide with stirring. The mixture was allowed to basify with stirring at room temperature for 1 hour. Thereafter, the alkalized holocellulose is filtered or centrifuged to a weight of 2 to 2.5 kg and transferred to a mixing and heating vessel. After addition of 0.24 L of epichlorohydrin and at 60 ° C, it is allowed to react for 1 hour. After the reaction, the product is washed with water until neutral, with ethanol or acetone and dried in the air. 1.1 kg of cross-linked holocellulose are obtained with a solubility in 5% sodium hydroxide - 5% ·

Example 2 kg of air-dry holocellulose of sorted spruce sawdust (particle size 0.1 to 3 mm and lignin content up to 5%) is mixed with stirring into an emulsion of 12 l of isopropanol and 1.2 l of 25% sodium hydroxide. The mixture was allowed to basify with stirring at room temperature for 1 hour. Thereafter, the alkalized holocellulose is filtered or centrifuged to a weight of 2 to 2.5 kg and transferred to a container with the possibility of stirring and heating. After the addition of 0.48 L of epichlorohydrin, it is allowed to react at 50 ° C for 2 hours. After the reaction, the product is washed with water until neutral, with ethanol or acetone and dried in the air. 1.3 kg of cross-linked holocellulose are obtained with a solubility in 5% sodium hydroxide - 3.5% ·

The invention has extensive application for the preparation of cation exchangers and anion exchangers based on crosslinked wood polysaccharides - holocellulose, which are applicable in analytical and preparative chromatography.

Claims (1)

PBBDMBT OF THE INVENTION A method for the preparation of cross-linked powdered holocellulose, characterized in that the sieved wood sawdust is after alkalization in an emulsion of sodium hydroxide and isopropyl alcohol using a weight ratio of: holocellulose - 25 to 30% sodium hydroxide - isopropyl alcohol, 1: 1.5 to 1.8 10 to 12, filtered at 20 to 25 ° C after 1 hour, or 20S 972 is centrifuged to 200-250% by weight of the aqueous weighing and crosslinked by adding 0.5 to 1 mole of a crosslinker, preferably epichlorohydrin, e at 50 to 60 ° C for 1 to 2 hours, then washing the fused product with water, ethanol or acetone and air dried.