RU2400511C2 - Method of processing pine tree bark - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method of processing pine tree bark involves extraction of the bark using a non-polar solvent with extraction of coniferous wax, subsequent extraction of pectin from the bark and treatment of the bark residue in activated carbon. After extraction of coniferous wax, the bark residue is extracted with 15% aqueous ethanol at boiling temperature for 0.5 hours. The extract is then filtered off, concentrated, saturated with sodium chloride and the obtained precipitate is separated. The filtrate is extracted with acetylacetate three times, concentrated to 1/8 of the initial volume and proanthocyanidins are settled with chloroform. The extraction agent used to extract pectin is 1% aqueous solution of hydrochloric acid.

EFFECT: method enables virtually complete utilisation of pine tree bark to obtain coniferous wax, proanthocyanidins, pectin and activated carbon.

1 dwg, 1 ex

Description

The invention relates to chemical processing of wood and can be used at woodworking enterprises and in the pulp and paper industry for processing pine bark to produce coniferous wax, proanthocyanidins, pectin and activated carbon.

Coniferous wax has biocidal and hydrophobic properties and is used to create protective coatings that are resistant to moisture, bacteria and fungi. The components of coniferous wax have a wide range of biological activity, on their basis a lot of medicines and cosmetics have been patented.

Proanthocyanidins are polyphenolic compounds and are one of the most widely used plant antioxidants [Bagchi, Bagchi et al. "Free radicals and grape seed proanthocyanidin extract: importance in human health and disease prevention." Toxicology "- 2000, 148 (2-3): p.187-97]. Proanthocyanidins are also used as biologically active food additives [RU 2199249 from 02/27/2003].

Pectins have anti-inflammatory, enveloping properties, exhibit a detoxifying effect, adsorbing toxins of microorganisms, heavy metal ions, including radionuclides, glycosides, alkaloids, phenol and other harmful substances. Pectins can be used in veterinary medicine for the prevention and treatment of gastrointestinal diseases of farm animals.

A known method of obtaining a complex of oligomeric proanthocyanidins (OPC) from the bark of a pine of the seaside (Pinus maritima). The method includes the following operations: extraction of crushed pine bark with boiling water, separation of the extract by filtration, its saturation with sodium chloride, separation of the precipitate formed by filtration, extraction of the filtrate with ethyl acetate, its concentration to 1/5 of the initial volume and dilution with three volumes of chloroform, followed by isolation of proanthocyanidins by filtration [US 4698360 dated 10/06/1987].

The disadvantage of this method is that the OPC complex is obtained from exotic raw materials - pine (Pinus maritima), which grows only in northern Canada and is difficult to breed, as well as the irrational use of raw materials, which leads to the formation of a significant amount of waste extracted bark.

A known method of producing pectin from pine bark by extraction with a 1% solution of ammonium oxalate (SU 563154, 06/30/1977).

The disadvantage of this method is the low range obtained from pine bark products.

The closest in technical essence and the achieved result is a method of processing spruce bark into coniferous wax, anthocyanidin dye, pectin and activated carbon. The method consists in extracting the cortex with a non-polar solvent (for example, hexane) with the extraction of coniferous wax, subsequent isolation of the anthocyanidin dye from the cortex by treatment with ethyl alcohol containing 2-5% hydrochloric acid, extraction of the cortex with a 0.5% aqueous solution of ammonium oxalate. at a temperature of 95-100 ° C with the release of pectin. The solid residue of the crust under conditions of oxidative carbonization is converted into activated carbons (RU 2332438, publ. 08.28.2008).

This method is intended for processing spruce bark. The disadvantage of this method is that a very valuable class of biologically active compounds, proanthocyanidins, is not extracted from the cortex. In addition, the disadvantages include the fact that the isolation of pectin is carried out with a 0.5% aqueous solution of ammonium oxalate, which leads to the contamination of pectin with ammonium oxalate.

The technical result of the invention is the expansion of the range of products obtained from pine bark and the achievement of its almost complete utilization with the production of coniferous wax, proanthocyanidins, pectin and activated carbon.

The technical result is achieved in that in a method for processing bark, including extraction of raw materials with a non-polar solvent with extraction of pine wax, subsequent isolation of pectin and processing of the remainder of the bark into activated charcoal, ordinary pine bark is used as raw material, and after isolation of pine wax the residue of pine bark is extracted 15 % aqueous ethanol at a boiling point for 0.5 hours, the extract is separated by filtration, concentrated, saturated with sodium chloride, the precipitate obtained is separated, the filtrate is thrice extra they agitate with ethyl acetate, concentrate to 1/8 of the initial volume, and proanthocyanidins are planted with chloroform, and 1% aqueous hydrochloric acid is used as an extractant to isolate pectin.

A comparative analysis of the proposed method and prototype shows that the common features are:

- extraction of coniferous bark with a non-polar solvent;

- isolation of pectin from the bark;

- processing of bark into activated carbon.

Distinctive features of the proposed method from the prototype are:

- The raw bark of common pine, which is one of the most common, arboreal species of Russian forests, is used as the feedstock.

- the selection of proanthocyanidins from the bark after extraction of coniferous wax is carried out with a water-alcohol solution;

- to isolate pectin as an extractant use a 1% aqueous solution of hydrochloric acid.

The invention is illustrated in the drawing, which shows a diagram of the process of waste-free processing of pine bark.

The method is as follows.

Pine bark is crushed, a fraction of less than 2 mm is taken and subjected to extraction at the boiling point with a non-polar solvent (hexane or gasoline) in a Soxhlet apparatus for separating coniferous wax. The yield of coniferous wax from the bark of pine is 4-5 wt.% By weight of the original bark.

The remainder of the bark is boiled in a water bath with 15% aqueous ethanol with vigorous stirring for 0.5 hours, then the hot water-alcohol solution is separated by filtration. The extract is concentrated in vacuo on a rotary evaporator 2.5 times from the original volume and saturated with sodium chloride, the resulting precipitate of polyphenolic substances is separated by filtration. The filtrate was extracted three times with ethyl acetate, each time using a volume of ethyl acetate equal to 1/2 the volume of the aqueous extract. Then the ethyl acetate extracts are combined, dried over anhydrous sodium sulfate, then concentrated in vacuo to 1/8 of the original volume and diluted 7 times with chloroform, while the proanthocyanidins precipitate in the form of light cream flakes, they are separated by filtration. The yield of proanthocyanidins is 0.6 wt.% By weight of the original cortex.

After obtaining proanthocyanidins, the residue of the pine bark is subjected to extraction with a 1% aqueous hydrochloric acid solution to isolate pectin.

The remainder of the crust remaining after the isolation of pectin is subjected to oxidative carbonization in a fixed or fluidized bed reactor at a temperature of 600-800 ° C. The output of activated carbon is 11-13%.

The method of processing pine bark is confirmed by a specific example.

Example. 100 g of crushed pine bark (fraction less than 2 mm) with a moisture content of up to 5% is loaded into a Soxhlet apparatus and extracted with hexane for 6 hours. After distillation of hexane, 4.6 g of coniferous wax are obtained; its yield is 4.8% by weight. by weight of the original absolutely dry bark.

In a 2 L round-bottom flask equipped with a stirrer and a reflux condenser, 100 g of tarless pine bark are charged, 1.5 L of 15% aqueous ethanol is poured and boiled in a water bath with vigorous stirring for 0.5 hour, then hot water the alcohol solution is separated by filtration and get 1.0-1.1 l of extract. The extract is concentrated under vacuum on a rotary evaporator to 350-400 ml and saturated with sodium chloride, the resulting precipitate of polyphenolic substances is separated by filtration. The filtrate was extracted three times using 200 ml of ethyl acetate, dried over anhydrous sodium sulfate, then the ethyl acetate solution was concentrated in vacuo to a volume of 60 ml and diluted 7 times with chloroform, while the proanthocyanidins precipitated in the form of light cream flakes, they were separated by filtration. The yield of proanthocyanidins was 0.6 g (0.6 wt.%) By weight of the initial cortex.

The residue of the pine bark after extraction of the proanthocyanidins is extracted with 1% aqueous hydrochloric acid. The extraction is carried out at a temperature of 100 ° C and a hydraulic module of 1:30. The solution is separated from the remainder of the cortex by filtration and concentrated in vacuo at a temperature of 50-55 ° C, then pectin is planted with ethanol. The precipitated pectin is separated by filtration, washed with alcohol and dried. The yield of pectin is 5.2%.

The remainder of the crust after separation of pectin by oxidative carbonization is converted to activated carbon in a fixed or fluidized bed reactor at a temperature of 600-800 ° C. The output of activated carbon is 11-13%.

Extraction with a water-alcohol mixture with an ethanol content of less than 15% leads to a decrease in the yield of proanthocyanidins (with an alcohol content of 10%, the yield of proanthocyanidins was 0.5%), and more than 15% to an increase in the degree of extraction of high molecular weight phenolic substances.

Thus, the proposed method allows to expand the range obtained from pine bark products, as well as to achieve its almost complete utilization.

Claims (1)

A method of processing pine bark, including extraction of the bark with a non-polar solvent to extract coniferous wax, subsequent isolation of pectin from the bark and processing of the remainder of the bark into activated carbon, characterized in that after separation of the coniferous wax, the remainder of the pine bark is extracted with 15% aqueous ethanol at a boiling point in for 0.5 h, the extract is separated by filtration, concentrated, saturated with sodium chloride, the precipitate obtained is separated, the filtrate is extracted three times with ethyl acetate, concentrated to 1/8 of the initial volume and proanthocyanidins are planted with chloroform, and a 1% aqueous hydrochloric acid solution is used as an extractant to isolate pectin.

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