REDUCTION OF SODIUM DICHROMATE IN PRESENCE OF VEGETABLE COMPONENTS

DOI: 10.6060/tcct.20165911.5378
Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2016. V. 59. N 11. P. 77-83

The conditions for the reduction of sodium dichromate in an acidic medium in the presence of vegetabile components were studied. As reducing agents it was suggested to use extracts of fir, oak and maltodextrin. The effect of flow rate and process of sulfuric acid dos-ing to the reaction mixture on the temperature in a reactor was investigated. It was shown that the effect of reducing reaction temperature depends on the type of vegetable components and conditions for its introduction into the reaction mixture. It was established that the main influence on temperature effect of the reduction reaction of sodium dichromate has a pH value of vegetable extracts solution. The portioned introduction of acid to the reaction system provided the optimal conditions. The influence of the type of vegetable component on the main characteristics of synthesis products – chromium vegetable tanning agents - was estab-lished. It was shown that by the reduction of sodium dichromate in the presence of vegetable extracts the chromium tanning agent with higher leather-processing properties and resistance to oxidation can be prepared. Plant extracts are oxidized to organic acids which are ligands embedding in the inner sphere of the chromium complexes. It provides their masking proper-ties. The best results on the content in the tanning agent of chromium oxide were obtained at the reduction of dichromate spruce extract. It was established that the cause of lowering the pH tanning agents in the course of dissolution is chromium complexes hydration. The high stability of the synthetic tanning agents to the action of alkaline reagents used in tanning technology to increase the basicity and stability of chromium complexes is connected with protein. The results of chemical analysis combined tannins derived at the reduction of sodium dichromate vegetable extracts, as compared to manufactured on an industrial scale dry chrome tanning agent are given. It was experimentally shown the absence of hexavalent chromium compounds in the skin treated with tanning agents.

Key words: sodium dichromate, synthesis, reduction, vegetable ingredients, tanning agent, vegetable extracts

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2016, Т. 59, № 11, Стр. 77-83

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