Energy-saving technology for betulin extraction from birch bark waste
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.