Organizing co mmittee

ACHIEVING SOLUBLE LIGNIN FROM LICORICE RESIDUES 
AND THEIR PHYSIOLOGICAL ACTIVITY 
B. B. Abduazimov, R.M. Khalilov 
 
S.Yu. Yunusov Institute of the Chemistry of Plant Substances Academy of sciences of the 
Republic of Uzbekistan st. Mirzo-Ulugbek, 77, 100170 Tashkent 
 
The accumulated remains of licorice roots in the territories of phytochemical 
enterprises must be refined according to terms of environmental and economic 
requirements. These wastes in their composition consist of biopolymers: hemicellulose, 
cellulose, and lignin. Lignin is the second most abundant natural polymer after 
polysaccharides, both of which form the matrix of plant biomass. Lignin is the most 
common aromatic polyfunctional biopolymer with an irregular heterogeneous structure 
synthesized in plant cells from the three alcohol monomers: p‐coumaryl alcohol, coniferyl 
alcohol, and sinapyl alcohol.
Lignin and hemicelluloses fasten bundles of celluloses, strengthening the walls of 
cell tissues and blood vessels, giving the plant mechanical strength. The biosynthesis of 
lignin in plants is essential for survival, despite abiotic and biotic environmental 
influences. The biodegradation of lignin is carried out by basidiomycetes from the 
white-rot fungi. Lignin is the basic source of formation humic and fulvic acids in nature. 
Recent times, research-sciences centers are strengthening of research and development 
of growth stimulators, plant protectors of plants from lignocellulose sources. 
We have searched the oxidative and hydrolytic degradation of lignocellulose residues 
of licorice roots. Water-soluble lignin was produced by the action of nitric acid and the 
alkaline destruction of the bonds between lignin and polysaccharides. 
The main factors in the extraction of water-soluble lignin with nitric acid depend 
substantially on the reaction temperature and acid concentration. The soaking process of 
residues in weak concentrations of nitric acid, achieved nitration of lignin and 
hydrolysis of phenolic ester bonds. Continuing the processes at more strong 
concentrations of nitric acid and temperature contributed to the nitration and oxidation 
of lignin carboxylated products. These products of nitrification and oxidation were 
transferred into solution due to alkali solutions. These products of nitrification and 
oxidation were transferred into liquid due to aqua-alkali solutions. 
Residues of licorice roots contained lignin 29.84% (according to Klasson), analyzes 
of lignin in residues after alkaline solution was 2.34%. Thus, 92.14% of lignin was 
extracted into solution from the residues of licorice roots. 
The alkaline solution after partial neutralization with acid solutions had a stable 
liquid form. Preliminary analyzes for physiological activity showed a stimulating 
activity on the germination of cotton seeds. 
Also, acidic solutions were used for the preparation of organic fertilizer. Because, it 
contained a large part of decomposition products of carbohydrates, lignin, and unreacted 
nitric acid. Therefore, the aqueous solution of ammonia was added to the waste liquid to 
neutralize it and increase the nitrogen content. The solution was dried. The dry organic 
fertilizer was a dark brown solid. The content of total nitrogen and organic matter in the 
fertilizer was 9.78% and 71.4%, respectively. Compared to some commercial fertilizers, 
content of total nitrogen and organic compounds are satisfactory and comparable. That 
show that the spent nitric acid liquid is suitable for the preparation of organic fertilizers. 

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Poster presentation 
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