The activation mechanism of Fe(II) ion-modified cassiterite surface to promote salicylhydroxamic acid adsorption

Abstract

This paper systematically analyzed the effects of Fe(II) ions on the cassiterite surface to promote the adsorption of salicylhydroxamic acid (SHA). The interaction behavior and mechanisms re investigated using micro-flotation experiments, adsorption experiments, zeta potential measurements, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The micro-flotation tests revealed that the Fe(II) ions had a strong activation effect on the cassiterite, and the recovery reached the maximum at pH values of 7–8. The results of the adsorption experiment showed that the adsorption capacity of SHA on the mineral surface significantly improved after Fe (II) ion activation; this result was confirmed by the zeta potential test. In addition, the zeta potential results indicated that the positively charged Fe species absorbed on the cassiterite surface led to positive changes in the mineral surface potential and an increase in the number of active sites, thereby increasing the SHA adsorption. The XPS and FTIR results demonstrated that the Fe(II) ions activated the cassiterite through the interaction of terminal oxygen atoms with Fe species on the cassiterite surfaces, and redox reactions and displacement reactions occurred between Fe2+ and Sn4+. SHA was chemisorbed on the cassiterite surface, allowing the anions to react readily with the Fe species to form Fe-SHA complexes. Therefore, the Fe(II) ion-activated cassiterite surfaces enhanced the strength and stability of the SHA chemisorption. Based on the results, an adsorption model of the Fe(II) ion-activated cassiterite surface in the SHA system was established.