Mobility of antimony during Sb(V)-bearing jarosite transformation: Influence of desferrioxamine B and oxalic acid.

Antimony (Sb) pollution is becoming a non-negligible issue due to its toxic and carcinogenic properties. In mining areas, jarosite is a main host mineral for Sb(V), and its transformation may seriously influence the fate of Sb. In this study, we examined the transformation of Sb(V)-coprecipitated jarosite in the presence of oxalic acid (OA) and Desferrioxamine B (DFOB), and explored the resulting repartition of Sb. Results showed that OA and DFOB retarded jarosite dissolution but promoted Fe(III) and Sb(V) release, playing a combined role in this retardation and promotion. In treatment without OA or DFOB, jarosite transformed into hematite and goethite. In DFOB-only systems, DFOB did not change the jarosite transformation pathway; goethite and hematite were still the dominant products, and aqueous Fe(III)-DFOB complexes were formed. In OA-only systems, the re-adsorption of aqueous Fe(III)-OA complexes on the mineral surface may result in another recrystallization pathway, forming goethite. In OA-DFOB systems, DFOB competed with OA for Fe(III), forming Fe(III)-DFOB complexes and delayed OA-induced jarosite transformation into goethite. By the end of all reactions, more than 99.94 % of total Sb was retained by neo-formed secondary Fe(III) minerals. OA drove more Sb to become phosphate-extractable, and DFOB drove the above phosphate-extractable Sb into poorly crystalline phases or residual phases.