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THE ACTION OF NITRIC ACID ON LIGNIN IN A WATER–DIMETHYL SULFOXIDE MIXTURE

Veshnyakov, V.; Yokubjanov, M.; Khabaro, Y.
Abstract:
Lignin as a by-product of chemical or biochemical processing of wood is usually burned to generate energy. However, its use as a source of chemicals and materials is considered more promising. Treatment of lignin with nitric acid is used in practice for its depolymerization. In our study, we investigated the treatment of Klason lignin with mixtures of concentrated nitric acid with dimethyl sulfoxide of various compositions. The effect of such treatments was evaluated by UV-Visible spectrophotometry of alkaline solutions of the formed products. Klason lignin was completely dissolved in alkaline medium after its treatment at 100°C for 10 min with mixtures of nitric acid with dimethyl sulfoxide of various compositions. Absorbance at 280 nm of the products in solutions decreased with an increase in the content of nitric acid in the initial reagent mixture that confirms a stronger degradation of lignin macromolecules. When the reaction mixture was diluted with distilled water there remained a residue, which was soluble only in the alkaline medium. The amount of the precipitate decreased with an increase in the content of nitric acid in the initial reagent mixture that may also be due to a stronger degradation of lignin macromolecules. The isolated precipitates were characterized by IR spectroscopy. IR spectra of the products have characteristic absorption bands of NO2 and C=O groups that confirms the processes of nitration and oxidation of lignin. The obtained effect of transforming the insoluble Klason lignin into a water-soluble form can be used to develop ways of hydrolysis lignin utilization.
SGEM Research areas:
Year:
2018
Type of Publication:
In Proceedings
Keywords:
lignin; nitration; dimethyl sulfoxide; depolymerization
Volume:
18
SGEM Book title:
18th International Multidisciplinary Scientific GeoConference SGEM2018
Book number:
4.3
SGEM Series:
International Multidisciplinary Scientific GeoConference-SGEM
Pages:
127-134
Publisher address:
51 Alexander Malinov blvd, Sofia, 1712, Bulgaria
SGEM supporters:
Bulgarian Acad Sci; Acad Sci Czech Republ; Latvian Acad Sci; Polish Acad Sci; Russian Acad Sci; Serbian Acad Sci & Arts; Slovak Acad Sci; Natl Acad Sci Ukraine; Natl Acad Sci Armenia; Sci Council Japan; World Acad Sci; European Acad Sci, Arts & Letters; Ac
Period:
3 – 6 December, 2018
ISBN:
978-619-7408-70-6
ISSN:
1314-2704
Conference:
18th International Multidisciplinary Scientific GeoConference SGEM2018, 3 – 6 December, 2018
DOI:
10.5593/sgem2018V/4.3/S05.016
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