The adsorption of a new derivative of mercaptothiazole on copper studied by XPS and AES

XPS (X-ray photoemission spectroscopy) and AES (Auger electron spectroscopy) have been used to study the adsorption of a new synthetic flotation collector, a derivative of mercaptothiazole (C6H6NS2K), on a polycrystalline copper surface in basic solution at various concentrations in order to characterize the nature of the surface film. The XPS Cu 2p, 5 2p, N 1s edges and CuL3M4.5M4.5 Auger line were detected. On interaction with the ligands copper is partially oxidized to Cu(I) indicating that the MT molecules interact directly with the copper atoms present on the surface. There is no evidence of any complex between copper and MT formed in the solution and precipitate. The analysis of CuL3M4.5M4.5 Auger spectra suggests that a chemical bond is formed between the collector and copper. There is a visible interaction between the ligands and the copper substrate, the effect of which is to prevent the oxidation of the metal even at very low concentration. The 2×10-4 M ligand concentration would appear to be the most efficient for ensuring the best corrosion inhibition under the experimental conditions adopted. From 7×10-4 M to 1×10-2 M the shape of the Auger line remains stable, showing that the Cu?MT component makes a relevant surface contribution. The chemical bond occurring between copper and the collectors does not change when the solution concentration is varied: in fact, there is no alteration in either the shape or the binding energy of the XPS signals from the S 2p and N 1s edges.