Computer Simulations of Quartz (101)–Water Interface over a Range of pH Values

Kroutil, Ondřej; Chval, Zdeněk; Skelton, Adam A.; Předota, Milan

doi:10.1021/acs.jpcc.5b00096

Cited by 106 publications

(158 citation statements)

References 72 publications

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“…This conclusion is consistent with X-ray reflectivity studies, 48,49 optical measurements, 50,51 and recent molecular simulations. 47,52 One consequence of this observation is that the surface charge as determined from an AFM (or SFA) force measurement, which is based on the ion distribution in the diffuse layer, is always lower than the charge density determined by a titration measurement that measures the total number of protons or ions adsorbing to or desorbing from a surface. 53 As a final remark, Fig.…”

Section: Charge Regulation and Local Fluid Compositionmentioning

confidence: 99%

Extracting local surface charges and charge regulation behavior from atomic force microscopy measurements at heterogeneous solid-electrolyte interfaces

et al. 2015

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We present a method to determine the local surface charge of solid-liquid interfaces from Atomic Force Microscopy (AFM) measurements that takes into account shifts of the adsorption/desorption equilibria of protons and ions as the cantilever tip approaches the sample. We recorded AFM force distance curves in dynamic mode with sharp tips on heterogeneous silica surfaces partially covered by gibbsite nano-particles immersed in an aqueous electrolyte with variable concentrations of dissolved NaCl and KCl at pH 5.8. Forces are analyzed in the framework of Derjaguin-Landau-Verwey-Overbeek (DLVO) theory in combination with a charge regulation boundary that describes adsorption and desorption reactions of protons and ions. A systematic method to extract the equilibrium constants of these reactions by simultaneous least-squared fitting to experimental data for various salt concentrations is developed and is shown to yield highly consistent results for silica-electrolyte interfaces. For gibbsite-electrolyte interfaces, the surface charge can be determined, yet, an unambiguous identification of the relevant surface speciation reactions is not possible, presumably due to a combination of intrinsic chemical complexity and heterogeneity of the nano-particle surfaces.

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Section: Charge Regulation and Local Fluid Compositionmentioning

confidence: 99%

Extracting local surface charges and charge regulation behavior from atomic force microscopy measurements at heterogeneous solid-electrolyte interfaces

et al. 2015

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“…At the natural pH of 6.2 used here, the charge density of silica was ca. −0.03 C/m 2 (value taken from Kroutil et al [37] and supported by Goloub et al [38]). Metal cations, when present, acted as counterions on the silica, adsorbing on the negative sites that dominated the surface.…”

Section: Zeta Potential and Cation Adsorptionmentioning

confidence: 69%

Analysis of Silica Pulp Viscoelasticity in Saline Media: The Effect of Cation Size

et al. 2019

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The effect of alkali metal chlorides on the viscoelastic behavior and yielding properties of silica suspensions was studied through creep-recovery and dynamic oscillatory tests with stress control. Then, the viscoelasticity of the pulps was correlated with the silica zeta potential, aggregate size, and the percentage of cations adsorbed on the surface of the ore. The results indicate that larger cations are more prone to adhere to the silica surface, which increases the number of ionic bonds that bind the particles. This generates stronger particle networks and a greater agglomeration of particles, especially those smaller than 10 µm. As the size of the bare cations increases, the rheological response provides higher values of yield stress, complex viscosity, and viscoelastic moduli, but in turn, pulps undergo minor deformations under the application of stress. Dynamic oscillatory tests suggest structural changes, with the phase angle following the inverse relationship with the bare cation size, indicating that the liquid-like character of the pulps increases as the size of the cations increases.Minerals 2019, 9, 216 2 of 15 water that surrounds them. Small ions such as Li + are known as maker ions because they attract water molecules more strongly than water molecules do to each other, forming a layer of structured water around the ions. On the other hand, large ions such as Cs + are known as breakers; they interact weakly with water, generating a layer of structureless water around them. This implies that the hydrated size of ions in solution follows the trend Li + > Na + > K + , which is opposite to the bare ion size.More than a century ago, Hofmeister related the precipitation of proteins with the size of bare ions in solution [8]; interestingly, the order established by Hofmeister has been found in various systems, such as colloidal suspensions of tungsten trioxide, magnetite, alumina, titanium, hematite, and silica [9][10][11][12][13]. Here, we focus on silica, which has been studied extensively due to its relevance in numerous industrial applications [14-16]; however, it has not been studied combining rheological and physicochemical results in the presence of a series of alkali metal chloride salts. A particularly important result for our work is that of Franks [9], who measured the zeta potential and yield stress of quartz suspensions in concentrated solutions of monovalent electrolytes, finding that poorly hydrated ions, such as Cs + and K + , have a greater impact in reducing the absolute value of the zeta potential than highly hydrated ions, such as Li + and Na + . Franks found a higher yield stress when the pulp was in the presence of breaker ions, although the results were highly dependent on the pH. A challenge that is not yet fully resolved is that of high isoelectric point minerals, such as alumina, the properties of which follow a trend with the size of ions opposite to silica; for example, maker ions generate stronger alumina networks [17][18][19][20][21]. Parson et al. [19] developed a Poisson...

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“…The pzc can control sorption of protons and hydroxyl groups, which depends on the acid-base properties of the surface (Pecenyuk 1999). Previous studies reported that the pzc for the PA components were 7.9, 5.4, 6.4, and 2.1, respectively, for magnetite (Tombacz et al 2006), hematite (Huang et al 2001), pyrite (Borah and Senapati 2006), and quartz (Kroutil et al 2015). In this study, the pzc values of the PA were determined to be 4.6.…”

Section: Resultsmentioning

confidence: 99%

黄铁矿灰渣去除溶解态砷

Türk

2016

Mine Water Environ

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Pyrite ash (PA), a waste produced during the roasting of pyrite ores to produce sulfuric acid, was studied as a potential adsorbent for removing arsenic (As) from groundwater. The collected pyrite ash waste samples contained [86 % iron (as Fe 2 O 3 ). The results indicate that adsorption of As by PA was only slightly affected by initial pH at pH B 9. Arsenate removal efficiency increased with the amount of adsorbent added over the range of 0.1-50 g/L. The As(V) removal increased with time, and 79 % removal was achieved within 1 h. Moreover, there was no significant change in As concentrations after 24 h. The adsorption process was best described by a second-order kinetic model. The adsorption of As(V) onto the PA was found to have followed the Langmuir isotherm. In batch studies, the maximum As(V) removal efficiency was 97 % at an adsorbent dose of 10 g/L, with an initial As(V) concentration of 300 lg/L. Thus, the PA was shown to be a suitable sorbent, reducing As from an initial level of 600 to\10 lg/L As(V), i.e., below the WHO limit for drinking water.

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Computer Simulations of Quartz (101)–Water Interface over a Range of pH Values

Cited by 106 publications

References 72 publications

Extracting local surface charges and charge regulation behavior from atomic force microscopy measurements at heterogeneous solid-electrolyte interfaces

Extracting local surface charges and charge regulation behavior from atomic force microscopy measurements at heterogeneous solid-electrolyte interfaces

Analysis of Silica Pulp Viscoelasticity in Saline Media: The Effect of Cation Size

黄铁矿灰渣去除溶解态砷

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