Identification and determination of xanthate, dixanthogen and sulfur xanthate by fast-sweep differential pulse polarography, a.c. polarography and cyclic voltammetry

Abstract

The chemical reactions occurring in the treatment of sulfide ores by flotation are still a matter of controversy when xanthates (I) are used as collectors. Either the metal xanthate and/or dixanthogen (II) or sulfur xanthates (III) could provide the required hydrophobicity for successful selective flotation. Because of the present difficulties in distinguishing between the various xanthate species by physical measurements, and electrochemical investigation in acetone was undertaken to see if rapid and reliable analytical methods could be developed for the simultaneous identification and determination of (I), (II), and (III). At platinum electrodes, (I), (II), and (III) give characteristic voltammetric waves at well separated potentials and cyclic voltammetry provides a simple means for their identification. At mercury electrodes all species give polarographic waves: (I) gives two extremely well defined oxidation waves with the one at more positive potentials being well removed from the waves for (II) and (III). The determination of (I) by fast-sweep differential pulse polarography is therefore possible over the concentration range lO -6–10 -2 M. (II) and (III) show less suitable d.c. polarographic behaviour and their reduction processes are complicated by adsorption. However, under a.c. polarographic conditions, (III) gives a well defined wave enabling its determination down to 10 -6 M. For (II), no wave was found at mercury electrodes at potentials separated from the waves arising from (I) and (III). The determination of (II) can therefore only be undertaken over the concentration range 10 -4–10 -2 M at platinum electrodes.