Method for Producing Graphite-Like Chitosan Structures by Thermolysis and Microwave Irradiation
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od for Producing Graphite-Like Chitosan Structures by Thermolysis and Microwave Irradiation N. Sh. Lebedevaa, S. S. Guseinova, Yu. A. Gubareva, E. S. Yurinaa,*, A. I. V’yugina, and O. N. Gavrilovaa a G.A.
Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, Ivanovo, 153045 Russia *e-mail: [email protected] Received July 2, 2020; revised August 24, 2020; accepted August 29, 2020
Abstract—The possibility of obtaining graphite-like structures from chitosan by microwave processing was studied. A comparative analysis of the products of pyrolysis and microwave treatment of chitosan was carried out. Keywords: chitosan, thermolysis, graphite-like structures
DOI: 10.1134/S1070363220110213 Chitosan is a linear polysaccharide composed of randomLy distributed β-(1→4)-linked D-glucosamine and N-acetyl-D-glucosamine units. The molar fraction of D-glucosamine units in chitosan characterizes its degree of deacetylation. Chitosan is one of the major cationic polymers and the second most abundant polysaccharide in nature [1]. As a biocompatible and nontoxic natural polymer, chitosan is useful for biomedical applications as a carrier of therapeutic agents such as peptides, proteins, vaccines, DNA, porphyrins, and medicines [2]. Also, chitosan is widely used in wound healing and burn treatment and also in gene therapy [3, 4]. Chitosan contains a large number of free amino groups capable of binding hydrogen ions and d-metal ions. This property underlies the use of chitosan as a sorbent, anionite, inactivator. A number of recent studies have focused on production of activated carbons from polysaccharides. In terms of their chemical structure, activated carbons are condensed aromatic graphite-like systems containing various functional groups. Depending on the synthesis or treatment (activation) conditions, it is possible to obtain activated carbons differing in the specific surface area and porosity, as well as materials with different pore volumes and shapes. Activated carbons are extensively applied as effective adsorbents for removal of a variety of organic and inorganic pollutants, polar and nonpolar compounds, from aqueous or gaseous media [5]. Electrode materials for supercapacitors is another promising application for activated carbons [6, 7]; they
can be used in solar energy [8] and food industry sectors [9], as well as in catalysis [10, 11] and extraction [12]. Polysaccharides, with their high carbon content, can be considered as readily available, renewable raw materials for activated carbon production. Currently, a technology for producing activated carbons by pyrolysis of cellulose, chitosan, and other polysaccharides is under development. Specifically, graphite-like structures are obtained by heat treatment of polysaccharides at 700–800°C in an inert atmosphere; various activators (Н2О2, KOH, Na2CO3, ZnCl2 [13, 14]) altering the textural properties of the carbonized material can be introduced into the initial biopolymer. The heat treatment appears to be a slow multistage process which requires c
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