On the interpretation of the XPS spectra of adsorbed layers of flotation collectors - Ethyl xanthate on metallic lead

Ethyl xanthate adsorption on metallic lead was studied by X-ray photoelectron spectroscopy (XPS) after treatment of lead sample at different potentials in aqueous NaNO3 solutions containing ethyl xanthate. Continuous increase of the amount of ethyl xanthate species on the lead surface was observed as the potential was raised from -400 mV to -340 mV at the ethyl xanthate concentration of 104 M. At the potential of -400 mV and the concentration of 10(-4) M the amount of xanthate at the surface was at the detection limit. Lead oxide and lead carbonate were found as the main oxidation products of metallic lead. Ethyl xanthate layer was found to decompose to sulfide like species in a few hours of excitation with monochromatic AIK(alpha) radiation, if XPS measurement was done at room temperature. Cooling the sample with liquid nitrogen down to T approximate to 430 K prevented the decomposition.