5-METHYL-2-MERCAPTOBENZOXAZOLE ADSORBED ONTO CHALCOCITE (CU2S) - AN XPS AND X-AES STUDY

XPS (X-ray Photoemission Spectroscopy) and X-AES (Xray excited Auger E lectron Spectroscopy) studies have been carried out on the reaction be tween natural chalcocite and solutions of 5-methyl-2-mercaptobenzoxazo le, a new synthetic flotation collector and a derivative of mercaptobe nzoxazole (C8H7NOS) (MMBO), The XPS Cu(2p), Cu(3s), S(2p), N(1s), O(1s ), and C(ls) lines and Cu L(3)M(4,5)M(4,5) X-ray excited Auger electro n spectra were detected for the Cu-MMBO complex and for chalcocite sur faces before and after immersion in MMBO solutions at different concen trations (from 10(-6) to 10(-3) M) and in water, The S(2p), N(1s), O(1 s), and C(1s) lines were recorded for MMBO bulk sample, The analysis o f Cu L(3)M(4,5)M(4,5) Auger spectra and the binding energy shift of th e S(2p) and N(ls) peaks from the MMBO during the adsorption suggest th at a chemical bond is formed between collector and chalcocite. The che mical bond occurring between copper atoms and collector species does n ot vary with the solution concentration; in fact there is no alteratio n in either the shape or the binding energy of the S(2p) and N(ls) lin es, On the basis of Cu L(3)M(4,5)M(4,5) Auger spectra and the quantita tive analysis of the S(2p) and Cu(3s) peaks, it seems possible to sepa rate monolayer and multilayer adsorption from each other, No evidence of any Cu(II)species on the surface was found. (C) 1995 Academic Press , Inc.