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

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

ACS Omega. 2021 Feb 3;6(6):4212-4226. doi: 10.1021/acsomega.0c03980. eCollection 2021 Feb 16.

Authors

Haosheng Wu¹, Axel D Renno¹, Yann Foucaud², Martin Rudolph¹

Affiliations

¹ Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Helmholtz Institute Freiberg for Resource Technology (HIF), Chemnitzer Str. 40, Freiberg 09599, Germany.
² ICSM, Univ Montpellier, CEA, CNRS, ENSCM, Marcoule, Bagnols-sur-Cèze 30207, France.

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.