Electrochemical behavior of chalcocite exposed to 2-mercaptobenzothiazole aqueous solution

[Display omitted] •The MBT adsorbs on chalcocite through its exocyclic sulphur, in addition to its endocyclic nitrogen bonding at negative potentials.•Deeply cathodic polarization of the chalcocite electrode (−600 mV or lower) can totally inhibit MBT adsorption onto its surface. The flotation of copper bearing minerals is always a hot topic in the field of minerals processing. In this paper, the adsorption of a flotation collector, 2-mercaptobenzothiazole(MBT), onto a typical secondary copper sulfide mineral, chalcocite, depending on electrochemical potential was investigated with the help of shell-isolated nanoparticle enhanced Raman spectroscopy (SHINERS). The MBT adsorbs through its exocyclic sulfur, in addition to its endocyclic nitrogen at negative potentials. This is because negative potentials are thermodynamically unfavorable for the adsorption to occur. Especially, chalcocite electrode that has been exposed to deep negative potential (−600 mV versus SCE) can be totally inhibited from MBT adsorption. A “cathodic passivating” process is proposed possibly accompanied by the formation of a passivation layer, kinetically preventing adsorption, even after potentials switch back to positive. Cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS) were also used to explain this phenomenon. The present work implicates enhanced separation efficiency of chalcocite by using electrochemical controlled flotation.