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The Effect of Complexing on the Zinc Dissolution in Dichromic Acid with HF Additions |
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18.09.2008 г. |
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The Effect of Complexing on the Zinc Dissolution in Dichromic Acid with HF Additions A. M. Shcherbakov Zhitomir Pedagogical University, ul. B. Berdichevskaya 40, Zhitomir, 10008 Ukraine Received December 17, 2003 Abstract — Two concentration ranges of activating hydrofluoric acid additions were distinguished when dis-solving zinc in a 2.5 M CrO3 solution. Zinc dissolves slowly in a range of 0.05 to 0.3 and quickly from 0.4 to mol/l HF. The effect is explained by the involvement of F– ions in the formation of Cr(III) fluoride complexes during the reduction of dichromic acid anions and ZnF+ cations during zinc ionization. Ionic equilibrium was calculated after long-term holding zinc in the CrO3 solutions with various HF contents. It was shown that com-plexing hinders the growth of passive oxide and salt films based on ZnF2 or basic Cr(III) chromate on zinc. DOI: 10.1134/S0033173206030118
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