Surface spectroscopic study of the adsorption of Ni(II) on pyrite and arsenopyrite at pH 10

Sorption of Sr(II) and Eu(III) onto pyrite under different redox potential conditions

“…The isoelectric points resulting from these extrapolations are given in Table 2. As previously reported in the lit- [5,23], the isoelectric point of the oxidized solid was slightly higher than the one of the non-oxidized solid, however the difference was small enough (0.3 pH unit in NaCl) to indicate that the behavior of the oxidized solid was not utterly governed by iron oxyhydroxide or other ferric phases. The isoelectric point of the non-oxidized solid was coherent with the literature values [22][23][24] and no significant shift was observed when conducting the measurements in NaCl or NaClO 4 , suggesting no specific adsorption of chloride ions on the non-oxidized pyrite surface.…”

“…The sorbing properties of pyrite have been well studied under oxidative conditions, with some articles particularly dedicated to the effect of oxidation processes on sorption [4,5]. Such studies generally described retention properties with natural pyrites.…”

New insights about the bacterial oxidation of arsenopyrite: A mineralogical scope

“…In this work, there are two primary sources of iron, i.e. ferrous sulfate added as a nutrient and the ions of iron product of the bioleaching of arsenopyrite; based on the results, the action of the iron could happen in accordance with the following sequence: (i) transformation of the ferrous iron, present as sulfate in the culture medium, to ferric iron, through an indirect mechanism (Sand et al, 1999); (ii) the ferric iron generated, will act in two ways: (a) Arsenopyrite oxidation by direct chemical oxidation, as part of the indirect mechanism proposed by Sand et al (1999), and (b) as a constituent of the extracellular polymeric substances (EPSs), in an indirect contact mechanism, mediating either in the adhesion mechanism of A. ferrooxidans to the mineral surface and in the biooxidation process; (iii) bioleaching of iron (as Fe 2+ and Fe 3+ , according with Hacquard et al, 1999) from the arsenopyrite, increasing concentration in ferric iron in solution, generating the incipient precipitation of jarosite (evident in this work after 4 hours of process). After several days (5 days in this work), the precipitation of jarosita increases considerably, nevertheless generating discontinuous films (probably porous), allowing the progressive oxidation of the mineral.…”

Aplicaciones biotecnológicas en minería aurífera: Estado del arte sobre la oxidación bacteriana de arsenopirita (FeAsS)

“…Los resultados de éste estudio mostraron que luego de 32 días de reacción en condiciones ácidas se liberaron al medio 1340 ppm de hierro y 886 ppm de arsénico. Hacquard et al (1999) trabajando sobre la adsorción de Ni(II) sobre la superficie de la arsenopirita, demostraron que la superficie del mineral era fuertemente oxidada, debido a la catálisis del Ni(II), y que casi todo el Fe(II) fue oxidado, el As(-I) pasó a As(V). El azufre fue descrito para varios estados de oxidación entre los que se encontraron disulfuros, polisulfuros y sulfatos.…”