Surface-Potential Heterogeneity of Reacted Calcite and Rhodochrosite

Na, Chongzheng; Kendall, Treavor A.; Martin, Scot T.

doi:10.1021/es070979p

Cited by 30 publications

(39 citation statements)

References 38 publications

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“…In particular, exposure to water vapor induces phase changes to hydrated layers composed of amorphous calcium carbonate hydrates and vaterite [268,276,277], as shown in Figure 65 surface under humid environments. Reproduced with permission from Elsevier [268].…”

Section: Sulfidesmentioning

confidence: 99%

Surface chemistry of carbon dioxide revisited

Taifan

Boily

Baltrušaitis

2016

Surface Science Reports

153

129

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This review discusses modern developments in CO 2 surface chemistry by focusing on the work published since the original review by H. J. Freund and M.W. Roberts two decades ago (Surface Science Reports 25 (1996) 225-273). It includes relevant fundamentals pertaining to the topics covered in that earlier review, such as conventional metal and metal oxide surfaces and CO 2 interactions thereon. While UHV spectroscopy has routinely been applied for CO 2 gas-solid interface analysis, the present work goes further by describing surface-CO 2 interactions under elevated CO 2 pressure on non-oxide surfaces, such as zeolites, sulfides, carbides and nitrides. Furthermore, it describes salient in situ techniques relevant to the resolution of the interfacial chemistry of CO 2 , notably infrared spectroscopy and state-of-the-art theoretical methods, currently used in the resolution of solid and soluble carbonate species in liquid-water vapor, liquid-solid and liquid-liquid interfaces. These techniques are directly relevant to fundamental, natural and technological settings, such as heterogeneous and environmental catalysis and CO 2 sequestration.

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Section: Sulfidesmentioning

confidence: 99%

Surface chemistry of carbon dioxide revisited

Taifan

Boily

Baltrušaitis

2016

Surface Science Reports

153

129

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“…There are also a number of studies that use the phyllosilicate mineral mica as a substrate. − KPFM has been widely used in materials sciences to investigate surface potential distribution in metals, semiconductors, insulators, and biological and organic materials, − though it has rarely been applied to natural minerals. While this technique is seldom used to analyze insulating mineral surfaces, KPFM is a potentially powerful method to analyze the laterally resolved electronic structure of surfaces. − To our knowledge, this study is the first application of surface potential mapping to understand the mechanism of wettability alteration.…”

Section: Introductionmentioning

confidence: 99%

Understanding Calcite Wettability Alteration through Surface Potential Measurements and Molecular Simulations

et al. 2017

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Mineral wettability and wettability alteration are important factors that determine the distribution and mobility of oil during the recovery process. Because wettability is dependent on many factors (e.g., hydrocarbon composition, mineralogy, and pH), predicting mineral wettability is often difficult. The goal of this study is to look at changes that occur on the mineral itself, specifically changes in the surface structure and surface potential, using experimental methods complemented by quantum-mechanical calculations to better understand the molecular-level processes involved in wettability alteration. Nanoscale surface imaging is combined with Kelvin probe force microscopy (KPFM) to characterize changes in topography and surface potential for water-wet (hydrophilic) and oil-wet (hydrophobic) calcite surfaces, using the surfactant hexamethyldisilazane (NHSi2(CH3)6, HMDS) to render the calcite surface oil-wet. KPFM measurements show that HMDS adsorbs preferentially on step edges of the calcite surface and is coupled by an increase in surface potential, which suggests a decrease in electron density in the valence band wherever HMDS is adsorbed. Density functional theory (DFT) calculations of HMDS adsorption on calcite confirm an increase in the surface potential of oil-wet calcite and show that Ca corner sites are associated with the most favorable HMDS adsorption energies. Coadsorption of H+ and OH– with HMDS is more likely to occur at edges and Ca kink sites and indicates that this surfactant may be an effective wettability modifier at a range of pH conditions. This study is the first application of KPFM to mineral wettability and demonstrates that with further development KPFM can be a powerful tool to study interactions between specific functional groups and surface sites modifying the surface’s electronic structure and wettability.

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“…Extended exposure of calcite to humid air produces nanometer-thick surface islands, presumably through the precipitation of mobile ions, of hydrated calcite or vaterite . Further extension of exposure time leads to the growth of islands into continuous films. − AFM force measurements show that surface islands and films dominate the underlying carbonates in van der Waals and electrostatic interactions. − Given the generally recognized importance of carbonate mineral dusts in the atmosphere, these humidity-induced nanostructures can control the overall surface reactions between dust particles and atmospheric constituents such as nitric oxides, − sulfur dioxides, ,− and organic acids. − …”

Section: Introductionmentioning

confidence: 99%

Opposing Effects of Humidity on Rhodochrosite Surface Oxidation

Tang

Wang

et al. 2015

Langmuir

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Rhodochrosite (MnCO3) is a model mineral representing carbonate aerosol particles containing redox-active elements that can influence particle surface reconstruction in humid air, thereby affecting the heterogeneous transformation of important atmospheric constituents such as nitric oxides, sulfur dioxides, and organic acids. Using in situ atomic force microscopy, we show that the surface reconstruction of rhodochrosite in humid oxygen leads to the formation and growth of oxide nanostructures. The oxidative reconstruction consists of two consecutive processes with distinctive time scales, including a long waiting period corresponding to slow nucleation and a rapid expansion phase corresponding to fast growth. By varying the relative humidity from 55 to 78%, we further show that increasing humidity has opposing effects on the two processes, accelerating nucleation from 2.8(±0.2) × 10(-3) to 3.0(±0.2) × 10(-2) h(-1) but decelerating growth from 7.5(±0.3) × 10(-3) to 3.1(±0.1) × 10(-3) μm(2) h(-1). Through quantitative analysis, we propose that nanostructure nucleation is controlled by rhodochrosite surface dissolution, similar to the dissolution-precipitation mechanism proposed for carbonate mineral surface reconstruction in aqueous solution. To explain nanostructure growth in humid oxygen, a new Cabrera-Mott mechanism involving electron tunneling and solid-state diffusion is proposed.

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Surface-Potential Heterogeneity of Reacted Calcite and Rhodochrosite

Cited by 30 publications

References 38 publications

Surface chemistry of carbon dioxide revisited

Surface chemistry of carbon dioxide revisited

Understanding Calcite Wettability Alteration through Surface Potential Measurements and Molecular Simulations

Opposing Effects of Humidity on Rhodochrosite Surface Oxidation

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