Dissolution of nickel oxide in oxalic acid aqueous solutions
The dissolution of nickel oxide (bunsenite) in acid solutions containing oxalic acid has been studied at 70.0°C. The dependencies of the rate of dissolution on total oxalate concentration and on pH have been explained by assuming a mechanism involving the transfer of two different surface complexes,...
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| Autores principales: | , , , |
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| Formato: | JOUR |
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_00219797_v244_n2_p353_Figueroa |
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| Sumario: | The dissolution of nickel oxide (bunsenite) in acid solutions containing oxalic acid has been studied at 70.0°C. The dependencies of the rate of dissolution on total oxalate concentration and on pH have been explained by assuming a mechanism involving the transfer of two different surface complexes, I and II, that predominate in different pH ranges. The rate law is R = k1 {I} + k2 {II}, where {} denotes surface concentration. The values k1Ns = 3.04 × 10-3 mol Ni m-2 s-1, k2Ns = 1.84 × 10-3 mol Ni m-2 s-1, together with the stability constants K1 = 675 mol-1 dm3 and K2 = 60 mol-1 dm3 fit all the results very well. The species formed in more acidic media is both more stable and more reactive. The possible structures of I and II are discussed on the basis of Fourier transform IR spectroscopy evidence in the literature. © 2001 Elsevier Science. |
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