SYNTHESIS OF CHROME TANNING AGENT IN PRESENCE OF OLIGO - AND POLYSACCHARIDES
Abstract
The conditions for the synthesis of chrome tanning agent during the reduction of sodium dichromate with oligo - and polysaccharides have been investigated. The synthesis of the tanning agent is based on the reduction of hexavalent chromium Cr (VI) in the form of sodium dichromate with reducing agents from the class of vegetable oligo- and polysaccharides with a different sequence of their introduction into the reaction mixture in the presence of sulfuric acid. The introduction of sulfuric acid was carried out gradually to avoid overheating and splashing of the reaction mixture, since the reduction reaction is accompanied by a significant thermal effect. Glucose, maltodextrin and pectin were used as reducing agents. The properties of the obtained products were evaluated by spectrophotometry, conductometry, and analytical methods. It has been shown that the use of native pectin leads to the formation of a gel like mass due to the coordination of the functional groups of galacturonic acid, which is part of the pectin, with chromium atoms. Pretreatment of pectin with a citric acid solution and optimization of synthesis conditions made it possible to obtain a chromium tanning agent that does not contain unreduced chromium. The influence of oligosaccharides on the properties of chromium tanning agents, including their ability to dissolve, is considered. It is shown that the reduction of sodium dichromate with maltodextrin during the reaction results in the formation of incomplete oxidation products of the oligosaccharide, which cause the masking effect of the chromium complex and increase in the resistance of the tanning agent to the action of alkaline reagents used to increase in the basicity during tanning. Experimental samples of chrome tanning agent in dry form were obtained and their leatherprocessing characteristics were studied. The results of technological tests have confirmed the theoretical propositions, according to which the high hydrothermal stability of the leather semifinished product, the almost complete depletion of the processing solution and the required physical and mechanical properties of the finished leather are achieved by introducing the products of incomplete oxidation of oligosaccharides into the inner sphere of the chromium complex.
References
Josep M. Morera, Esther Bartolí, Roberto Chico, Cristian Solé, Luisa F. Cabeza. Minimization of the environ-mental impact of chrome tanning: a new process reusing the tanning floats. J. Cleaner Product. 2011. V. 19. N 17–18. Р. 2128-2132. DOI: 10.1016/j.jclepro.2011.07.018.
Chandrasekaran B., Rao J.R., Sreeram K.J. Chrome tanning: State-of-art on the material composition and characterisation. J. Sci. Indust. Res. 1999. V. 58(1). P. 1-10. DOI: 10.2307/777874.
Chursin V.I. Technological processes and ecology of leath-er production. M.: FGBOUVO "RGU im. A.N. Kosygina". 2019. 161 p. (in Russian).
Levina A., Lay P.A. Mechanistic studies of relevance to the biological activities of chromium. Coord. Chem. Rev. 2005. N 6. P. 281-298. DOI: 10.1016/j.ccr.2004.02.017.
Chursin V.I., Andrievskaya O.K. Recovery of sodium bichromate in the presence of plant components. CheChemTech [Izv.Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2016. V. 59. N 11. P. 77-84 (in Russian). DOI: 10.6060/tcct.20165911.5378.
Sebastian E. Bellua, Juan C. Gonzaleza, Silvia I. Garcıaa, Sandra R. Signorellaa, Luis F. Salaa. Kinetics and mechanism of oxidation of applepectin by Cr VI in aqueous acid mediumy. J. Phys. Org. Chem. 2008. V. 21. P. 1059–1067. DOI: 10.1002/poc.1281.
Hassan A. Ewais, Mohamed K. Ismael, Ahmed A. Abdel-Khalek. Kinetics and mechanism of the formation and oxidation of iminodiacetato–chromium(III) complex. J. Saudi Chem. Soc. 2009. V. 13. N 2. P. 219-225. DOI: 10.1016/j.jscs.2009.05.001.
Yarutich A.P, Borzakova S.S, Bogdanov N.V, Makarov-Zemlyansky Y.Y. Coordination chemistry of dry chrome tanning agents. Kozh. Obuv. Prom. 2007. N 2. P. 34-35 (in Russian).
Donchenko L.V., Nelina V.V., Karpovich N.S. Influence of temperature on pectin extraction. Pishch. Prom-t’. 2008. N 6. P. 31-35 (in Russian).
Ovodov Y.S. Modern concepts of pectin substances. Bioorgan. Khim. 2009. V. 5. N 3. P. 293-310 (in Russian). DOI: 10.1134/S1068162009030017.
Cherkashin I.V. Chursin V.I. Reduction of sodium dichromate in the presence of lignosulfonates. Dizain Tekhnol. 2012. N 31. P. 86-91 (in Russian).
Ivanov V.M., Shcherbakova Y.I., Figurovskaya V.N. Optical and colorimetric characteristics of solutions of analytical forms of sulfate, chloride and chromium acetate. Vestn. Moskov. Un-ta. 2011. V. 52. N 6. P. 413-418 (in Russian). DOI: 10.3103/S0027131411060034.
Danilkovich A.G, Chursin V.I. Analytical control in the production of leather and fur. M.: Infra-M. 2016. 172 p. (in Russian)
Chursin V.I., Obolenskaya K.V. The use of glyoxal in the preparation of a composite chrome tanning agent. Zhurn. Priklad. Khim. 2011. V. 84. N 12. P. 1999-2003 (in Russian). DOI: 10.1134/S1070427211120123.
Kadyrova R.G., Kabirov G.F., Mullakhmetov R.R. Biological properties and synthesis of complex salts of ɑ-amino acids of biogenic metals. Kazan’: Kazan. gos. Energ. Univ. 2014. 108 p. (in Russian).
Kornev V.I., Mikryukova G.A. Homo- and heteropolymeric complexes of chromium III with complexones of a number of carboxymethyleneamines and hydroxycarboxylic acids in aqueous solutions. Vestn. Udmurt. Univ. Khimiya. 2006. N 8. P. 163-180 (in Russian).
Frascaroli M.I., Signorella S., González J.C., Mangiameli M.F., García S., Rubin de Celis E., Piehl L., Sala L.F., Atria A.M. Oxidation of 2-amino-2-deoxy-d-glucopyranose by hypervalent chromium: Kinetics and mechanism. Polyhedron. 2011. V. 30. P. 1914-1921. DOI: 10.1016/j.poly.2011.04.028.
Zayko G.M., Shapiro Y.M. Chelate complexes in the com-position of pectin preparations and the problem of pectin purification Izv.Vyssh. Uchebn. Zaved. Pishch. Tekhnol. 2000. N 5-6. P. 24-25 (in Russian).
Bartholomäus R., Irwin J.A., Shi L., Smith S.M., Levina A., Lay P.A. Isolation, Characterization, and Nuclease Ac-tivity of Biologically Relevant Chromium(VI) Complexes with Monosaccharides and Model Diols. Likely Intermedi-ates in Chromium-Induced Cancers. Inorg. Chem. 2013. V. 52 (8). P. 4282-4292. DOI: 10.1021/ic3022408.
Golubev V.N., Shelukhina N.P. Pectin: pectin, chemistry, technology, application. M.: Izd. akademii tekhnologicheskikh nauk RF. 2005. 272 p. (in Russian).
