UDC

547.992.3:542.943-92’7

Authors

Beloglazova Aleksandra Leonidovna
Northern (Arctic) Federal University named after M.V. Lomonosov (Arkhangelsk, Russia)
e-mail: a.beloglazova@narfu.ru
Popova Natalya Radievna
Institute of Theoretical and Applied Chemistry, Northern (Arctic) Federal University named after M.V. Lomonosov (Arkhangelsk, Russia)
e-mail: n.popova@narfu.ru
Bogolitsyn Konstantin Grigoryevich
Northern (Arctic) Federal University named after M.V. Lomonosov; Institute of Ecological Problems of the North, Ural Branch of the Russian Academy of Sciences (Arkhangelsk, Russia)
e-mail: k.bogolitsin@narfu.ru

Abstract

Environmentally friendly ways of plant material processing stimulate an interest for eco-friendly oxidizers, in particular for molecular oxygen, hydrogen peroxide and peracetic acid. Catalysts are used to intensify these processes. The paper aimed to identify key mechanisms of catalytic oxidation of lignin compounds in acid medium. The authors studied the influence of рН solution, catalyst concentration, and temperature on the oxidation of spruce dioxane lignin and technical lignin with peracetic acid catalyzed by Mn-assisted molybdovanadophosphate polyoxoanion. We have established that increased pH leads to a decrease in the content of carboxyl groups in the high-polymeric fraction of lignin oxidation products. It is connected with fewer carbocationic structures being formed, which, in its turn, reduces the oxidation rate. The decreased content of carboxyl groups in the high-polymeric fraction of the oxidation products is explained by intensified decarboxylation at raised temperature. Higher catalyst concentration produces different effects on the content of carboxyl groups and the yield of high-polymeric fraction of dioxane lignin oxidation products and that of technical lignin. Technical lignin proved to be more reactive in catalytic oxidation with peracetic acid than dioxane lignin.

Keywords

dioxane lignin, technical lignin, catalytic oxidation, polyoxometalate

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