Use of an Evaporated Gold SERS Substrate to Detect 2-Mercaptobenzothiazole on Sulfide Mineral Surfaces

Abstract

The interaction of 2-mercaptobenzothiazole (MBT) with the sulfide mineral surfaces, chalcopyrite (CuFeS2), chalcocite (Cu2S) and synthetic copper sulfide (CuxS) thin films, was investigated by Raman spectroscopy. Gold was evaporated onto the sulfide surface to facilitate surface enhancement of Raman scattering. Raman and gold-induced SERS spectra from mineral surfaces exposed for various times to solutions of different MBT concentrations, recorded before and after gold decoration, were used to elucidate the mechanism of collector adsorption. Spectra were identified with MBT bonded to copper atoms in the mineral surface and not to bonding to the gold overlayer. Spectra obtained from each sulfide surface displayed the band arising from the NCS ring stretch vibration of MBT downshifted from its position from CuMBT. The shift was similar to that found previously for MBT chemisorbed on a copper metal electrode. MBT chemisorbs to copper atoms in the mineral surfaces through the exocyclic sulfur atom.