Reaction Layer Formation on MgO in the Presence of Humidity.

Mineralization by MgO is an attractive potential strategy for direct air capture (DAC) of CO due to its tendency to form carbonate phases upon exposure to water and CO. Hydration of MgO during this process is typically assumed to not be rate limiting, even at ambient temperatures. However, surface passivation by hydrated phases likely reduces the CO capture capacity.

Improving Rare-Earth Mineral Separation with Insights from Molecular Recognition: Functionalized Hydroxamic Acid Adsorption onto Bastnäsite and Calcite.

Enhancing the separation of rare-earth elements (REEs) from gangue materials in mined ores requires an understanding of the fundamental interactions driving the adsorption of collector ligands onto mineral interfaces. In this work, we examine five functionalized hydroxamic acid ligands as potential collectors for the REE-containing bastnäsite mineral in froth flotation using density functional theory calculations and a suite of surface-sensitive analytical spectroscopies. These include vibrational sum frequency generation, attenuated total reflectance Fourier transform infrared, Raman, and X-ray photoelectron spectroscopies.

A Molecular-Scale Approach to Rare-Earth Beneficiation: Thinking Small to Avoid Large Losses.

Separating rare-earth-element-rich minerals from unwanted gangue in mined ores relies on selective binding of collector molecules at the interface to facilitate froth flotation. Salicylhydroxamic acid (SHA) exhibits enhanced selectivity for bastnäsite over calcite in microflotation experiments. Through a multifaceted approach, leveraging density functional theory calculations, and advanced spectroscopic methods, we provide molecular-level mechanistic insight to this selectivity.

Molecular Recognition at Mineral Interfaces: Implications for the Beneficiation of Rare Earth Ores.

Ce-bastnäsite is the single largest mineral source for light rare-earth elements. In view of the growing industrial importance of rare-earth minerals, it is critical to develop more efficient methods for separating the valuable rare-earth-containing minerals from the surrounding gangue. In this work, we employ a combination of periodic density functional theory (DFT) and molecular mechanics (MM) calculations together with the molecular design program HostDesigner to identify bis-phosphinate ligands that preferentially bind to the (100) Ce-bastnäsite surface rather than the (104) calcite surface.

Adsorption mechanism of alkyl hydroxamic acid onto bastnäsite: Fundamental steps toward rational collector design for rare earth elements.

Rare earth element (REE) production is limited in part by inefficient strategies for beneficiation. Hydroxamic acid ligands are promising reagents for the selective flotation of bastnäsite [(Ce,La)FCO], a major REE ore mineral, but the mechanism and energetics of adsorption are not understood, interfering with the design of new, more efficient reagents. Here, the adsorption of octyl hydroxamic acid onto bastnäsite was measured using a combination of experimental and computational methods.