Study of the Influence of the Crystallographic Orientation of Cassiterite Observed with Colloidal Probe Atomic Force Microscopy and its Implications for Hydrophobization by an Anionic Flotation Collector.

Haosheng Wu,Axel D Renno,Yann Foucaud,Martin Rudolph

doi:10.1021/acsomega.0c03980

Abstract

In this study, the physicochemical behaviors of the (110), (100), as well as (001) of SnO2 were investigated by using high-resolution direct force spectroscopy. The measurements were conducted between a silica sphere and sample surfaces in 10 mmol/L KCl between pH 3.1 and 6.2 using colloidal probe atomic force microscopy (cp-AFM-hydrophilic). Dissimilar interactions were detected on different-oriented surfaces. The pH values where the force switched from positive to negative can be clearly distinguished and be ordered as SnO2(100) < SnO2(001) ≈ SnO2(110). By fitting the force curves in the Derjaguin–Landau–Verwey–Overbeck theory framework, anisotropic surface potentials were computed between the three sample surfaces following a similar trend as force interaction. To study the implication of crystallographic orientation to surfactant adsorption, we used Aerosol 22 (sulfosuccinamate) as an anionic collector for cassiterite flotation to functionalize the different samples at pH 3. The contact angle measurements, the topography visualizations by AFM, and the force measurement using cp-AFM with hydrophobized spheres (cp-AFM-hydrophobized) have shown that Aerosol 22 was adsorbed on the sample surfaces inhomogeneously. The adsorption followed the range of SnO2(110) > SnO2(100) > SnO2(001) in the concentration from 1 × 10–6 to 1 × 10–4 mol/L.

Highlights

With the development of electronic devices, global tin demand has significantly and continuously increased over the past decades
Colloidal force measurements for different crystallographic orientations of minerals have been intensively explored.6−13 For instance, the study of Gao and co-workers14 analyzed the interactions between silicon nitride cantilever tips and three scheelite (Ca[WO4]) cleavage surfaces by using high-resolution atomic force spectroscopy (AFM)
We investigated the differences in terms of surface potential between the three main cleavage planes of cassiterite, namely the [110], [100], and (001) surfaces

Summary

Introduction

With the development of electronic devices, global tin demand has significantly and continuously increased over the past decades. Colloidal force measurements for different crystallographic orientations of minerals have been intensively explored.− For instance, the study of Gao and co-workers analyzed the interactions between silicon nitride cantilever tips and three scheelite (Ca[WO4]) cleavage surfaces by using high-resolution atomic force spectroscopy (AFM). They calculated the surface potential values by fitting the force data to the Derjaguin− Landau−Verwey−Overbeck (DLVO) theory and demonstrated that the electrostatic potential for (001) surface was only slightly affected by pH. Bullard and Cima have used AFM to measure interactions between a silica sphere

Methods

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Discussion

Conclusion