RU2004592C1 - Method of tannin substances preparation from milled larch bark - Google Patents

Description

phenols), which leads to the need to refine the tannin extract with ion exchange resins, and this. on the one hand, it significantly reduces the initial effect of increases in the yield of extractive substances and, on the other hand, greatly complicates the technological scheme; secondly, the selected solvent has a complex component composition, which is difficult to maintain constant, as a result of which there is a problem of its reuse, and the methanol present in the mixture poses a danger in working with the solvent; thirdly, the presence of a complex organic solvent complicates the technological scheme in terms of the recovery of gas emissions and disposal of waste soda.

The aim of the present invention is to increase the yield of tannins, improve their quality and simplify the process.

The goal is achieved in that the bark is crushed to a particle size of 2-10 mm and subjected to extraction with Nefras A 65/75 gasoline to separate lipids at a temperature of 60-65 ° C, a hydraulic module of 1: 15-20 for 4 hours. The residue was extracted with hot water or aqueous ethanol at a temperature of 90-95 ° C or 72-75 ° C, respectively, with a water module of 1: 20-30 for 6 hours.

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

Lipid extraction is carried out at the boiling point of gasoline, which contributes to a high lipid recovery rate. The hydromodule 1:20 makes it possible to achieve a saturation concentration of gasoline with lipids and therefore an increase in the hydromodule does not lead to a positive effect. A drop in the hydraulic module below 1:15 leads to a sharp decrease in the recovery factor. After removal of lipids, the extraction of tannins takes place under favorable conditions and the yield upon extraction with hot water increases by 6.4%, and upon extraction with aqueous ethanol by 7.5-7.7%. The recovery rate for this increases by 1.6-1.8 times compared with the prototype. In addition, lipid recovery will provide an enterprise with a valuable commercial product.

The experimentally selected conditions of the extracted / tannins allow extraction in an exhaustive way.

mode (coefficient of extraction of tannins from the crust - 90-97.5%).

The selected parameters (time, hydraulic module, temperature) contribute to the 5 extraction of tannides and netannides in the optimal ratio, providing good quality,

The temperature of 75 ° C is limited by the boiling point of the water-alcohol mixture. At 0, the extraction temperature of tannins is lower than 72 ° C, even with a high hydraulic module (1:30) and a duration of 6 hours, complete recovery is not achieved (recovery rate 88.3%). Pr1 / water module extracting tannins below 1:20 leads to a sharp decrease in recovery rate (75.5%), and increasing the water module above 1:30 does not increase the yield of tannins.

Extraction of tannins was carried out using BODMSGO ethanol. The addition of ethanol changes the polarity of the extractants and, therefore, its solubility in relation to

5 and highly condensed tannidism, which contributes to an increase in the yield of tannins in general.

The proposed method compares favorably with the prototype in that for isolation

0 tanning extract requires fewer process steps, the hydromodule is reduced 4.8 times, and consequently the number of evaporators and energy costs are reduced. The prototype does not indicate the duration

5 of the second and third stages, but the outcome of the hydromodule can be assumed that this time should be significant and many times greater than the time of the proposed method.

0

The proposed method is illustrated by the following examples.

PRI me R 1, 50 g of crushed (2-10 mm) larch bark are loaded into the extractor

5 with a moisture content of 10%, which contains 3% of lipids, 18.2% of tanning agents and is poured with 280 g Nefras A 65/75 gasoline (water module 1:18). Extraction is carried out three times at a temperature of 60 ° C for 1 h 20 min,

0 The extract is filtered off and evaporated at a residual pressure of 60 mm Hg. and temperature 25 ° С. The lipid yield is 1.44 g (2.9% of the A. bark). The recovery rate is 96.6%.

5 Resin-free bark is extracted three times with 15% aqueous ethanol in an amount of 400 g (water module 1:25) at a temperature of 75 ° C. The total arem of extraction is 6 hours. As a result, 8.8 g of tannins are recovered, which makes up 17.6% of A. bark. The recovery rate is 96.7%. The tannic extract had a pH of 5, contained 65.0% tannides, 21.2% netannides, and the benignness of the extract was 74.6%.

Example 2. 50 g of crushed larch bark with the characteristic of Example 1 are loaded into the extractor, 280 g (hydraulic module 1:18) of Nefras A 65/75 grade gasoline are poured. Extracted three times at a temperature of 60 ° C for 1 h 20 min. The extract is filtered off and evaporated at a residual pressure of 100 mm Hg. and a temperature of 40 ° C. The yield of lipids is 1.44 g (2.9% of the a.s. of the cortex). The recovery rate is 96.6%. The tarred bark is extracted three times with water in an amount of 400 g (water module 1:25) at a temperature of 90 ° C, the total extraction time is 6 hours. The yield of tannins is 8.2 g (16.4% of the ac.s. bark), the recovery rate is 90.0%.

The obtained extract had a pH of 5, contained 64.9% of tannides, 29.2% of netannides, and the benignness of the extract was 70.0%.

Other examples are given in table 1, and the composition and quality of the obtained tannic extracts in table 2.

As can be seen from the data given in Tables 1 and 2 of the proposed method, the yield and coefficient of extraction of tannins increases while simplifying the process, the tannin extract significantly exceeds the prototype in terms of mass fraction of tannides and good quality.

In the Novosibirsk branch of the Moscow Technological Institute of Light Industry (NFMTILP), laboratory tests of tanning a sheepskin were performed with tanning extracts obtained by equal methods. From the test results it follows that the indicators characterizing the tanning properties of the extracts from the experimental water-alcohol extract

The characteristics of the extract from Quebracho are close, and the aqueous and essential industrial larch extracts are somewhat superior.

Thus, the proposed method

will allow

To increase the yield of tannins when removing hot water by 6.4%, and when extracting with aqueous ethanol by 7.5 - 7.7% compared with the prototype.

To increase the recovery ratio of tannins in 1.6-1.8 times compared with the prototype,

Get a benign tannin extract. The mass fraction of tannids in comparison with the prototype increases by 3-19%, benignness by 5-26%.

To simplify the technological process in comparison with the prototype and analogs, since a neutralization step is not required and a sulfitizing agent is excluded in production.

Improve the business economy by improving the quality of the tannin extract and the additional release of a new marketable lipid product.

(56) N.A. Yartseva. Tannins in the bark of coniferous Siberia, Krasnosk, 1987.

USSR copyright certificate No. 196230, cl. C 14 C 3/00, 1967.

USSR copyright certificate No. 717135, cl. C 14 C 3/00, 1980. USSR Copyright Certificate No. 162911, class. C 14 C 3/00, 1964.

Astapkovich And, And. Getting tannin

extract from Siberian larch bark

using a water-alcohol solution of alkali. Abstract of dissertation,

Riga, 1983

USSR copyright certificate No. 1089128, cl. C 14 C 3/00, 1984.

Table 1

Continuation of table 1

Table 2 The composition and quality of tannic extracts obtained in various ways

Note Values of indicators are given in the range of their variation.

Claims (1)

The claims 45 pounds of lipid are extracted with a hydromodule of 1:15 - 20, of nutrients at a temperature of 90 - 95 C and a guide or water-alcohol solution METHOD FOR PRODUCING DUBILIC SUBSTANCES FROM MILLED LARCH BARK by their extraction, characterized in that the lipids are preliminarily separated by extraction with gasoline at a hydromodule of 1:15 - 20, and the extraction of tannins is carried out with water at a temperature of 90 - 95 C and a hydromodule of 1:20 - 30 or a water-alcohol solution at a temperature of 72 - 75 C and a water module of 1:20 - 30.