Face or Edge? Control of Molybdenite Surface Interactions with Divalent Cations

作者：Zhenzhen Lu, John Ralston, Qingxia Liu · 发表于：The Journal of Physical Chemistry C · 年份：2019 · DOI：10.1021/acs.jpcc.9b07632 · 被引用次数：31 · 研究领域：Iron oxide chemistry and applications、Minerals Flotation and Separation Techniques、Electrochemical Analysis and Applications

Molybdenite, MoS 2, a 2-D transition metal dichalcogenide, is a potential substitute for graphene. Molybdenite mineral particles are separated from gangue minerals by flotation, a process often performed in saline waters, where the presence of divalent cations can cause serious selectivity issues. A fundamental question is posed: how do divalent cations, which are subject to hydrolysis as a function of pH, interact with anisotropic molybdenite surfaces? By use of a combination of atomic force microscopy (AFM) surface force measurements with time-of-flight secondary ion mass spectrometry (ToF-SIMS) surface spectroscopy, the surface potentials and surface ion species of MoS 2 immersed in aqueous MgCl 2 and CaCl 2 solutions were distinguished for the face and the edge surfaces, respectively, for the first time. The adsorption mechanisms of Mg II and Ca II on anisotropic MoS 2 surfaces are revealed as a function of pH, ion species in solution, and solid characteristics (dielectric constant and surface chemical groups). As a consequence of these fundamental insights, improved particle flotation pathways are available.