RU2400357C2 - Method for processing of conifer bark - Google Patents

Abstract

FIELD: wood working industry.

SUBSTANCE: invention relates to method for processing of conifer bark. Method for processing of conifer bark includes bark grinding, serial extraction with hydrocarbon dissolvent and water, concentration of extract and extraction of target fractions of lipids and polyphenol. After extraction of lipids and polyphenols, remaining bark is exposed to hydrolysis-extraction with acidified water at the temperature of 70-75°C, hydraulic modile 1:(2.0-2.5), for 6-7 hours, with further concentration of extract by method of ultrafiltration at the temperature of 40-47.5°C and pressure of 0.4-0.45 MPa, depositing fraction of pectine substances by aliphatic alcohol, separation of pectines deposit by centrifugation and spray-drying at the temperature of 40-40.9°C and pressure of 0.3-0.38 MPa. Remained extracted bark is used to produce bark compost fertilisers.

EFFECT: suggested method makes it possible to extract biologically active substances from bark to the maximum.

2 tbl, 1 ex

Description

The invention relates to a method for processing bark of coniferous trees and can be used in the pulp and paper industry and in enterprises engaged in woodworking. The proposed method involves the selection contained in the bark of valuable biologically active substances, increasing the use of biomass of coniferous trees and the qualified use of spent bark.

At large pulp and paper and wood processing enterprises as a result of tree debarking, a large mass of bark accumulates annually - 7-15% of the volume of processed wood. Currently, almost all of the resulting bark is sent to the dump, accumulates, polluting the air and water basins of the adjacent region, while the bark, unlike wood, except for the main components (cellulose, lignin) contains a significant proportion (up to 20%) of biologically active substances, primarily lipids, polyphenols, pectin substances. Due to their unique properties, all these products are widely used in various industries.

Known methods of processing bark in order to isolate certain biologically active substances of the bark: lipids, polyphenols, pectins.

The known method [1] (RF Patent No. 2086616 of 05/28/1996, "Method for the production of lipids and wax from the bark of coniferous trees") processing the bark of coniferous trees in order to isolate lipids, which consists in extracting plant materials with a non-polar hydrocarbon solvent, concentration extract to a solids content of 6-10%, cooling the concentrate to 15-20 ° C, separating the wax separated together with lipids, washing with a non-polar hydrocarbon solvent and obtaining lipids after distillation of the solvent and volatile impurities with water vapor. The yield of lipids is 2.6% of A. with. bark, the recovery rate of 96.6%. The resulting lipids have high performance, allowing them to be used to obtain intermediates in the cosmetic industry.

The disadvantage of this method is the incomplete use of plant materials, the release of only about 3% of biologically active substances of the bark of coniferous trees. The method of disposal of the bark remaining after the extraction of lipids, the authors have not proposed.

The known method [2] (AS USSR No. 563154 from 08.01.74, "Method for the production of pectin from plant materials") processing of bark of pine, larch, spruce for the extraction of pectin substances is as follows:

- mechanical cleaning of the bark from contamination; crushing to particles with a size of 1-2 mm;

- removal of water-soluble substances at a temperature of 60 ° C;

- extraction of pectin from the bark with a 0.5% aqueous solution of ammonium oxalate at 100 ° C, the ratio of raw material to extractant 1:30;

- clarification of the extract with activated carbon;

- concentration of the extract in vacuum evaporators;

- isolation of pectin with 96% ethyl alcohol for 10 hours;

- drying wet pectin and grinding dry pectin on a grinder.

The disadvantages of this method of processing bark are: the allocation of only one biologically active product - pectin; extraction of water-soluble substances at a temperature of 60 ° C does not ensure their complete extraction, because water-soluble substances are non-hydrolyzable tannids, which are known to be extracted from the bark of coniferous trees only at a temperature of 70-90 ° C; the extractant selected for the isolation of pectin - oxalic ammonium - is not selective and, in addition, interacts with the pectin molecule to form partially ammidated pectin; the subsequent additional stage of clarification of the extract containing tannins with activated carbon is not effective, because activated carbon is not an adsorbent for tannids; high temperature extraction of pectins will lead to additional extraction of tannins; a high hydraulic module of the extraction process leads to an increase in the duration of the process, increasing energy costs for production; inclusion of an additional stage of the process - grinding of the finished product. The combination of these disadvantages does not allow to obtain high quality pectin, which significantly limits the direction of its use. The authors do not indicate the yield of pectin and its qualitative characteristics, only noting that coniferous pectin is suitable for the production of marmalade and canned products on its basis.

The known method [3] (RF Patent No. 2122033 from 11/20/98, “Method for producing tannic extract from larch bark”) processing larch bark in order to obtain polyphenols used as tanning agents in the leather industry, involves crushing the bark and extracting it with water alcohol and aqueous solutions of sodium hydroxide for 5-5.5 hours at a temperature of 65-75 ° C; subsequent extraction of the residue with hot water at 90-95 ° C; combining the obtained extracts; neutralization with acetic acid to a pH of 6.8-7.2. After neutralization, the extract is treated with formaldehyde and sodium sulfite to refine alkaline extracts. Extraction of substances of phenolic nature is up to 50% of the mass of a.s.v., good quality is not lower than 62%.

The known method [4] (System technology for processing wood bark with the allocation of tanning agent and recycling odubina - Chemistry and use of extractive substances of the tree: Sat. dokl. Scientific. Conf., 1990), offering a system technology for processing wood bark with the extraction of tanning agent and recycling Odebins - bark obtained after extraction. The process is carried out in several stages:

- extraction of tannins with a water-alcohol solution of alkali, in which the polyphenols are extracted almost completely from the bark, which makes it possible to classify the spent bark - odubin - as raw material suitable for hydrolytic processing;

- hydrolysis of the odubin with sulfuric acid in order to obtain monosugars with a mass fraction of glucose up to 80% of the total sugar. The hydrolyzate (feed sugar) obtained after neutralization can be used as a carbohydrate supplement in feed for farm animals;

- oxidative destruction of the solid residue after hydrolysis (technical lignin) in order to obtain carboxylic acids that can be utilized by microorganisms. The product of this processing is protein feed yeast.

The proposed methods have the following disadvantages:

- low degree of utilization of biomass of bark: only one biologically active substance, polyphenols, used as tanning agents in the leather industry, is to be extracted;

- the absence of a stage of lipid extraction, which, when used in the extraction of polyphenols with hydroalcoholic alkali, leads to the extraction of the extractive substances accompanying them - saponified lipids and phenols and requires an additional stage of purification of the extracts;

- alkaline extraction of the release of polyphenols (tannins) reduces the yield of native products due to their partial oxidation, which makes it possible to use them only as tannins in the leather industry, thereby limiting the scope;

- there is no stage of extraction of pectin substances from the bark, which does not allow to obtain a valuable natural product, which is of great importance for the production of medical, veterinary drugs, medical food products.

None of the above known methods for producing biologically active substances provides for the integrated use of valuable plant materials - the bark of coniferous trees, does not fully extract all the valuable components - biologically active substances contained in the bark. According to known methods, about 90-97% of the organic substances of the cortex pass into the waste, which can be extracted and find highly qualified use.

Closest to the proposed method is a known method for producing tannins from the crushed larch bark [5] (RF Patent 2004592 dated December 15, 1993, “A method for producing tannins from the crushed larch bark”), which is selected as the prototype.

The essence of the method is as follows: larch bark, crushed to particle sizes of 2-10 mm, is subjected to extraction with Nefras A 65/75 gasoline to separate lipids at a temperature of 60-65 ° C (water module 1: 15-20) for 4 hours. The residue is extracted with hot water or aqueous ethanol at a temperature of 90-95 ° C or 72-75 ° C, respectively, with a hydraulic module of 1: 20-30, for 6 hours.

Preliminary extraction of hydrophobic lipids facilitates the access of hydrophilic extractants to tightly bound tannides and ensures their high yield from the extracted material.

The specified method has the following disadvantages:

- incomplete use of the biologically active mass of bark of coniferous trees - only by 10-13%;

- the bark remaining after extraction, lipids and polyphenols contains valuable biologically active substances - pectins, however, this method does not provide for their isolation;

- the lack of additional purification of the isolated fractions of polyphenols does not allow their use as therapeutic veterinary drugs used in the disease of calves and poultry;

- not provided a method of disposal of the bark remaining after extraction.

The aim of the present invention is the technology of complex processing of bark of coniferous trees with the maximum release of biologically active substances, improving the quality of selected products in order to expand their areas of application and the complete rational utilization of raw materials, which is a waste product.

This goal is achieved by the fact that the bark of coniferous trees (larch, spruce, pine) are crushed to particle sizes of 2-10 mm and subjected to sequential extraction with solvents of increasing polarity. To extract a fraction of hydrophobic substances - lipids - the bark is extracted with a non-polar hydrocarbon solvent - gasoline - at a temperature of 60-65 ° C, a hydraulic module of 1: 15-20 for 4 hours. Then, to extract hydrophilic substances - the fraction of polyphenols - the bark is extracted with a polar solvent - hot water - at a temperature of 90-95 ° C, a hydraulic module of 1: 20-30 for 6 hours. After that, the bark is subjected to hydrolysis extraction with acidified water at a temperature of 70-75 ° C, a water module of 1: 2.0-2.5, a duration of 6-7 hours. In this case, pectin substances located in the cortex in the form of protopectin pass into a water-soluble state, which contributes to their most complete extraction from the bark.

The concentration of extracts of polyphenols and pectin substances is carried out by ultrafiltration at a temperature of 40-45 ° C and a pressure of 0.4-0.45 MPa.

Precipitation of pectin substances from the concentrate is carried out with aliphatic alcohol (ethyl or isopropyl alcohol), followed by separation of the suspension by molecular weight using the centrifugation method.

The drying of polyphenols and pectin substances is carried out in a spray-type dryer, excluding the stage of grinding of the finished product.

The extracted bark with a humidity of 50%, remaining after the extraction of biologically active substances from it, is dried and used as the basis for bark compost fertilizers.

The invention is illustrated by the following examples.

Example 1. For extraction using crushed (2-10 mm) larch bark.

The bark is fed into the extractor. At the same time, to extract lipids, a hydrocarbon solvent (gasoline) heated up to a temperature of 65 ° C, a hydromodule 1:15, an extraction time of 4 hours are fed into the extractor. The resulting lipid extract is concentrated in a rotary film evaporator. The solvent is distilled off at a temperature of 25 ° C and a residual pressure of 60 mm Hg, a lipid concentrate is collected as a finished product. The lipid yield is 2.9% of a.s. bark, the recovery rate of 96.6%.

After the lipids are separated, water is fed into the extractor to extract the polyphenols. The temperature of the extraction process is 90 ° C, the hydraulic module is 1:25, and the contact time is 6 hours. The obtained polyphenol extract is concentrated by ultrafiltration at a temperature of 40 ° C and a pressure of 0.4 MPa, where the monosugars and polyphenols obtained during water extraction are also separated and the extract is concentrated. Next, the polyphenol concentrate is dried in a spray dryer at a temperature of 40 ° C and a pressure of 0.4 MPa. The yield of polyphenols is 17.6% of A. with. cortex, the recovery rate of polyphenols 98.7%.

After the isolation of lipids and polyphenols, the cortex is then sent to an extractor, where at a temperature of 70 ° C, a water module of 1: 2.0 and a duration of 6 hours, hydrolysis is carried out by extraction of protopectins with acidified water.

The concentration of the extract of pectin substances is carried out by ultrafiltration at a temperature of 45 ° C and a pressure of 0.4 MPa. Then the fraction of pectin substances is precipitated from the concentrate with aliphatic alcohol (ethanol), separating the precipitate of pectin in a centrifuge under normal conditions. The drying of pectin sediment is carried out in a spray dryer at a temperature of 40 ° C, a pressure of 0.3 MPa. The output of pectin substances is 2.7% of A. with. cortex, the recovery ratio of pectins 98.5%.

Extracted bark with a moisture content of 50% is discharged from the extractor, dried.

From 1 ton of larch bark, 26.2 kg of lipids, 158.4 kg of polyphenols, 24.3 kg of pectin substances, 870 kg of extracted bark (50% moisture) are obtained.

Tree bark contains almost all the basic nutrients that, in the process of its mineralization, become available to plants. It has good humus-forming potential, carbon dioxide emitted during its mineralization improves the carbon nutrition of plants. When nitrogen is introduced into its composition, the extracted bark is an effective organo-mineral fertilizer. When using composts based on extracted bark, grain yield increases by 20-25%. From 870 kg of extracted bark, 875-910 kg of bark compost fertilizers are obtained.

To obtain comparative data on extraction, experiments were carried out with various types of bark, the conditions for the isolation of biologically active substances (pectin substances) were changed. The results are summarized in table 1.

Quality indicators of products obtained from various types of bark are shown in table 2.

As can be seen from the data shown in tables 1, 2, according to the proposed method, the coefficient of extraction of biologically active substances from the bark of coniferous trees is increased, the performance of polyphenols is increased, the mass fraction of pectin in the fraction of pectin substances extracted by this method allows us to use them not only in traditional applications (food, confectionery), but also as medical products for animals and people.

Using the proposed method for complex processing of bark of coniferous trees provides the following advantages compared to existing methods:

- full, rational use of bark of coniferous trees, which is a waste of pulp and paper and woodworking production;

- 100% use of tree biomass; an increase in the release of biologically active substances by 15-20%;

- the selected sequence of extractants (gasoline, water, acidified water), the application of the stage of concentration of extracts by ultrafiltration, mild conditions for the isolation of biologically active substances from extracts can preserve the nativeness of the products obtained, maximize their yield, improve performance and expand their scope: lipids in production cosmetic products; polyphenols in veterinary medicine, wine and juice production; pectin substances in veterinary medicine or as a biologically active food supplement to reduce radionuclides in the prevention and treatment of radiation sickness;

- the entire process of bark processing is carried out continuously;

- contribution to improving the environmental situation in the region, solving the problem of utilizing the bark formed at pulp and paper mills and woodworking enterprises, reducing the area of dumps, and reducing the company's environmental costs.

Claims (1)

A method of processing the bark of coniferous trees, including crushing the bark, sequential extraction with a hydrocarbon solvent and water, concentrating the extract and isolating the desired fractions of lipids and polyphenols, characterized in that after the isolation of lipids and polyphenols, the bark residue is subjected to hydrolysis extraction with acidified water at a temperature of 70-75 ° C, hydromodule 1: (2.0-2.5), for 6-7 hours, followed by concentration of the extract by ultrafiltration at a temperature of 40-47.5 ° C and a pressure of 0.4-0.45 MPa, precipitation fractions of pecti of new substances with aliphatic alcohol, separation of the precipitate of pectins by centrifugation and spray drying at a temperature of 40-40.9 ° C and a pressure of 0.3-0.38 MPa, the remaining extracted cortex is used for the production of crust fertilizers.