Electrochemical behaviour of galena (PbS) in aqueous nitric acid and perchloric acid solutions

Oxidation of arsenopyrite and deposition of gold on the oxidized surfaces: A scanning probe microscopy, tunneling spectroscopy and XPS study

“…On the other hand, one can notice a sympathetic correlation between the deposition of gold and the passivity of arsenopyrite surfaces. A similar parallel between passivation during anodic oxidation of galena and the quantity of metallic lead then deposited on the reacted surfaces at negative potentials was mentioned previously (Mikhlin et al, 2004a). The model of the disordered passive layer considers that the n-type conductivity and the potential fluctuations entail increased density of electrons at least on some surface spots, facilitating the reductive deposition of a metal.…”

“…Aside from elemental sulfur, thiosulfate, sulfate, various compounds of As in oxidation states up to +5, and Fe(III)-O species were found on arsenopyrite reacted under various conditions by XPS Walker, 1988-1989;Richardson and Vaughan, 1989;Nesbitt et al, 1995;Schaufuss et al, 2000;Costa et al, 2002;Jones et al, 2003;Mikhlin et al, 2003b), Raman spectroscopy (McGuire et al, 2001b,c;Costa et al, 2002), and X-ray absorption spectroscopy (XANES) (Mikhlin and Tomashevich, 2005). Several researchers Walker, 1988-1989;Nesbitt et al, 1995;Costa et al, 2002;Mikhlin et al, 2003a,b) pointed out the formation of nonstoichiometric, S-rich surface layers which were considered responsible for passivity of mineral sulfides (Buckley et al, 1985;Hackl et al, 1995;Mikhlin et al, 2003aMikhlin et al, , 2004a.…”

Electroanalytical chemistry for the analysis of solids: Characterization and classification (IUPAC Technical Report)

“…• Solid electrodes made of the material under investigation, e.g., for the analysis of minerals with semiconducting properties, typically magnetite [98][99][100] and galena [101][102][103]. Usually, the electrodes consisted of bars of the studied material housed in a Teflon shaft.…”

Electrochemical analysis of metallic heritage artefacts: voltammetry of microparticles (VMP)

“…The most common approaches for analysing corrosion products are depicted schematically in Fig. 9 case with magnetite [46] or galena [47]. This can be regarded as a bulk electrode modifi cation where the electrochemical reaction is initiated at the electrolyte/electrode boundary ( Fig.…”