Siberian Federal University

In the production of powdered cellulose by peroxide delignification of pretreated pine bark in the medium «acetic acid – water – catalyst MnSO4» the soluble by-products are formed with an yield of 27 % from mass of bark. They are presented by soluble acetic acid lignin, hemicelluloses and low-molecular weight organic compounds. The content of acetic acid lignin was 16.3 % from the total weight of soluble products, hemicelluloses – 5.9 %, water-soluble low-molecular products – 21.8 %, ethyl acetate- soluble products – 55.9 %. The structure and composition of lignin were established by FTIR, 31P NMR, SEM, EDS, and laser diffraction methods, and that of hemicelluloses – by FTIR and GC methods. The acetic acid lignin is characterized by a high content of hydroxyl groups. The average particle size of lignin was 2.17 μm. The following monosaccharides were found in the hemicelluloses composition: glucose – 47.4 rel. %, mannose – 31.1 rel. %, galactose – 11.8 rel. %, xylose – 9.6 rel. %. The low molecular weight soluble products of pine bark delignification were divided into ethyl acetate and aqueous fractions and analyzed by FTIR, GC and GC–MS methods. Malonic (16.49 rel. %) and glycolic (14.93 rel. %) acids predominated in the ethyl acetate fraction of soluble products. The hydrolysate of aqueous fraction contains glucose – 40.8 rel. %, mannose – 27.3 rel. %, xylose – 18.8 rel. %