The article presents a method for determining the mass conductivity coefficient of wood when extracting biologically active substances from it. To implement the method, there was an installation developed, the internal cavity of which is divided into two zones filled with liquids with different concentrations of the extracted substance. The installation zones are separated by the investigated wood material. The determination of the mass conductivity coefficient is made according to the equation obtained from Fick’s first law. As an approbation of the proposed method, we carried out studies on the mass conductivity coefficient of larch wood during the extraction of dihydroquercetin from it with a water-ethanol extractant and arabinogalactan with distilled water. As a result of experimental data processing, mathematical dependences of the larch mass conductivity coefficient during the extraction of dihydroquercetin and arabinogalactan on the process temperature were obtained, which can be used in mathematical modeling in order to optimize the operating parameters of the process.

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The paper presents experimental studies on the extraction of betulin from birch bark by one-stage extraction method in a flask with a reflux condenser and extraction in a Soxhlet apparatus. It is found that the highest betulin yield (up to 40 %) is achieved by extraction in a Soxhlet apparatus with periodic renewal of the extractant. The kinetic dependences obtained in the course of the research allows constructing an equilibrium dependence necessary to determine the rational number of phase contact stages when designing an industrial continuous extraction plant. On the basis of the studies carried out, a scheme of energy and resource-saving technology for extracting betulin from birch wood waste is proposed and a pilot plant is developed, which can be used to work out the modes of obtaining high-purity betulin. The absence of losses of organic extractants and the reuse of Florentine water determines the ecological purity of production. Refined birch bark can be used for the production of wood-polymer composite materials or as a fuel for generating thermal energy, which reflects the energy and resource-saving potential of this technology.

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As know, all wood material is recycled only half, and the rest of it remains unused. In practice, wood waste is most often plowed or burned, at a time when such wood is a valuable natural raw material that can compensate for the needs of a number of sectors of the economy. In this regard, the problem of recycling waste from the woodworking industry is very relevant today. Wood waste contains a large amount of substances capable of exhibiting biological activity. In particular, such biologically active substances include betulin, which is found in birch bark, which, due to its many advantages, has found wide application in medical, perfumery, cosmetic, food and other industries. For the rational use of wood and wood materials, it is necessary to develop new technologies and equipment for processing wood into products that are in demand for mankind. The paper provides an overview of the processing of birch bark. The relevance and prospects of birch species as a raw material for the chemical industry have been established. An installation for obtaining biologically active substances from wood waste is presented.