South African Journal of Chemistry
versão On-line ISSN 1996-840X
NETE, Motlalepula; PURCELL, Walter; SNYDERS, Ettienne e NEL, Johann T.. Alternative dissolution methods for analysis of niobium containing samples. S.Afr.j.chem. (Online) [online]. 2010, vol.63, pp. 130-134. ISSN 1996-840X.
Inductively coupled plasma optical emission spectrometry was applied for the qualitative and quantitative analyses of the different high purity Nb containing samples such as Nb metal, Nb2O5 and NbF5. Microwave-assisted digestion of the Nb compounds with concentrated H2SO4 in PTFE vessels produced Nb recoveries of 99.90 ± 0.08 % for Nb metal, 98.8 ± 0.7 % for Nb2O5 and 100.7 ± 0.4 % for NbF5. Fusion of Nb2O5 with Li2B4O7 flux and the subsequent dissolution of the melt with concentrated H2SO4 resulted in the precipitation of H3BO3 under these conditions. Methanol was added to the reaction mixture to convert the boric acid into the volatile methyl ester in an effort to remove the excess H3BO3. This procedure yielded a recovery of 103±2%for the pure Nb2O5 sample.
Palavras-chave : Niobium samples; microwave dissolution; fusion dissolution; qualitative analysis; quantitative analysis; validation.