Experimental and DFT insights into the oxidation-induced deterioration of sodium butyl xanthate adsorption on pristine and hydroxylated (001) surfaces of carrollite (CuCo2S4)

Abstract

Cobalt is a strategically important metal, but its efficient recovery from increasingly complex ores remains challenging. Flotation is widely used to recover cobalt sulfide minerals such as carrollite, with xanthates serving as common collectors. However, surface oxidation can impair flotation and cause substantial cobalt losses, while the mechanism governing xanthate adsorption failure on oxidized carrollite remains unclear. Here, sodium butyl xanthate (SBX) adsorption on oxidized carrollite was investigated using flotation, wettability and adsorption tests, spectroscopy, and density functional theory (DFT) calculations. H 2 O 2 -induced oxidation decreased surface hydrophobicity, suppressed SBX adsorption, and substantially reduced flotation recovery. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy showed that oxidation altered the surface chemical environment and weakened interactions between SBX and carrollite. DFT calculations revealed that surface hydroxylation weakened interactions of the C–S and C=S groups with sulfur active sites, destabilizing SBX chemisorption. In contrast, exposed metal sites retained their adsorption activity, indicating that hydroxyl species selectively hindered sulfur-mediated adsorption pathways. These findings clarify how surface hydroxylation suppresses xanthate adsorption on carrollite and provide a mechanistic basis for improving the flotation recovery of oxidized cobalt sulfide minerals.