A comprehensive study of the components of post-extraction residues of spruce woody greens

In this work, we conducted a comprehensive physicochemical study of the post-extraction residues of woody greens of Picea abies obtained in the production of the commercial biopreparation "Verva-spruce". The component composition of spruce woody greenery and its post-extraction residue was determined by chemical methods. It is shown that the biomass of P. abies woody greens and the residue after its emulsion processing are multicomponent system, the composition of which is represented by polymeric (lignocarbohydrate), low-molecular and mineral parts. Cellulose (36 mass.%) and lignin (29 mass.%) are the predominant fractions of post-extraction residues of spruce woody greenery. The functional composition of cellulose and lignin was studied by FTIR spectroscopy, chemical and elemental analysis in detail. It is shown that the spruce wood waste is characterized by a smaller amount of carboxyl and carbonyl groups, compared with woody greens. This is due to the fact that some of the hemicelluloses, pectin and lignin are removed during the alkaline extraction of woody greens. During the water-alkaline treatment of woody greens, a part of the water- and alkali-soluble fractions of proteins is removed, as evidenced by a decrease in the nitrogen content in the post-extraction residue. The supramolecular structure and morphology of the waste was studied by X-ray diffraction and electron microscopy. It is shown that the extraction of woody greens with a solution of alkali leads to loosening of the surface of the waste cellulose. The particle size of the waste lignin is reduced, and its surface becomes more homogeneous compared to woody green lignin. The obtained information is significant in the search for alternative sources of lignocellulose, which is the basis of valuable chemical and agricultural products, as well as for solving the problem of rational use of wood waste, and in particular coniferous woody greenery.