Abstract
Hydrolytic lignin is a large-tonnage waste product of ethyl alcohol production and is a renewable resource. The structure of lignin is characterized by the presence of a large number of hydroxyl groups, which provides the value of lignin as a raw material for synthesis in polymer chemistry. But due to their low chemical stability in dilute alkalis, acids and solvents, lignins are of little use for wide practical use. The introduction of additional functional groups into the lignin maromolecule by oxidative modification with the use of resource-saving technologies makes it possible to obtain new products for the synthesis of composite materials. On the basis of electrochemically modified lignin in polycondensation reactions with phthalic acid, ion-exchange materials have been obtained: weakly acidic cation exchangers with a exchange capacity of 0.1 mol/l NaOH 3.5-3.8 mmol/cm3, capable of sorbing cations in a wide range of pH values, and ampholyte (exchange capacity for sodium cation 6.4-6.6 mmol/cm3, for chlorine anion - 1.1-1.3 mmol/cm3). Ion exchangers synthesized on the basis of chlorine and nitro-containing lignins have been investigated in comparison with generally known industrial ion exchangers; they have high exchange and physic-mechanical characteristics and chemical resistance.
Highlights
The development of biologically based composites and nanocomposites is extremely important in the current environmental situation [1]
Lignins contain many hydroxyl groups that can participate in chemical reactions to produce value-added products [2]
The ability of natural lignins to adsorb organic and inorganic substances is due to the developed surface structure and interaction of functional groups, as well as the presence of hydrogen bonds
Summary
The development of biologically based composites and nanocomposites is extremely important in the current environmental situation [1]. The ability of natural lignins to adsorb organic and inorganic substances is due to the developed surface structure and interaction of functional groups, as well as the presence of hydrogen bonds. The GL structure is formed in the process of percolation hydrolysis, which is carried out at elevated pressures (0.6-0.9 MPa) and temperatures up to 200 °C In this case, a significant modification of the lignin macromolecule occurs. Oxidative modification of GL by electrochemical [6,7,8] and other methods [9, 10] leads to an increase in the content of functional groups and, in the sorption capacity of the lignin macromolecule. This publication presents the synthesis and properties of ion-exchange materials based on chlorine-, fluorine- and nitro-containing modified polyfunctional lignins and phthalic acid
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