Interfacial microstructures and adsorption mechanisms of benzohydroxamic acid on Pb2+-activated cassiterite (1 1 0) surface

Abstract

In this work, the interfacial microstructures and adsorption mechanisms of benzohydroxamic acid (BHA) on Pb2+-activated cassiterite (110) surface were investigated by means of Raman spectroscopy, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM) and density functional theory (DFT) calculations. AFM images showed that the roughness value of the natural cassiterite surfaces decreased after the treatment of Pb2+ and BHA with respect to the clean surface. The experimental high-resolution XPS spectra and the DFT calculated spectral lines consistently showed that the major surface species was the Pb-BHA complex on the cassiterite surface. The new peak of N1s at 401.88 eV in the X-ray photoelectron spectroscopy of cassiterite surface treated by BHA showed that BHA could be also chemically adsorbed on the surface. The Raman spectra revealed that the peak around 268 cm−1 should be attributed to the Pb-O bonds in the interface bonding structure of BHA-Pb-O≡. HR-TEM images of the clean, Pb2+ and Pb2+||BHA (adding BHA after Pb2+)-treated interfaces further demonstrated the interfacial microstructures. This work showed a new light on the understanding of the interface adsorption mechanism of flotation reagent and the activation mechanism of metal ion on oxidized mineral.