A radiotracer study on the kinetics of gold sorption by mineral surfaces

Fluorinated surfactants, which fall under the class of per- and polyfluoroalkyl substances (PFAS), are amphiphilic molecules that comprise hydrophobic fluorocarbon chains and hydrophilic head-groups. Fluorinated surfactants have been utilized in many applications, e.g., fire-fighting foams, paints, household/kitchenware items, product packaging, and fabrics. These compounds then made their way into the environment, and have been detected in soil, fresh water, and seawater. From there, they can enter human bodies. Fluorinated surfactants are persistent in water and soil environments, and their adsorption onto mineral surfaces contributes to this persistence. This review examines how fluorinated surfactants adsorb onto mineral surfaces, by analyzing the thermodynamics and kinetics of adsorption, and the underlying mechanisms. Adsorption of fluorinated surfactants onto mineral surfaces can be explained by electrostatic interactions, hydrophobic interactions, hydrogen bonding, and ligand and ion exchange. The aqueous pH, varying salt or humic acid concentrations, and the surfactant chemistry can influence the adsorption of fluorinated surfactants onto mineral surfaces. Further research is needed on fluorinated surfactant adsorbent materials to treat drinking water, and on strategies that can modulate the fate of these compounds in specific environmental locations.

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Role of mineral surfaces in kinetics of weathering

Water-Rock Interaction XIII ◽

10.1201/b10556-14 ◽

2010 ◽

Keyword(s):

Mineral Surfaces ◽

Kinetics Of

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Geochemical Reaction Modeling

10.1093/oso/9780195094756.001.0001 ◽

1996 ◽

Cited By ~ 13

Author(s):

Craig M. Bethke

Keyword(s):

Numerical Methods ◽

Natural Waters ◽

Environmental Geochemistry ◽

Vital Role ◽

Mineral Surfaces ◽

Practical Applications ◽

Reaction Processes ◽

Kinetics Of ◽

Geochemical Reaction ◽

Theoretical Foundations

Geochemical reaction modeling plays an increasingly vital role in several areas of geoscience, from environmental geochemistry and petroleum geology to the study of geothermal and hydrothermal fluids. This book provides an up-to-date overview of the use of numerical methods to model reaction processes in the Earth's crust and on its surface. Early chapters develop the theoretical foundations of the field, derive a set of governing equations, and show how numerical methods can be used to solve these equations. Other chapters discuss the distribution of species in natural waters; methods for computing activity coefficients in dilute solutions and in brines; the complexation of ions into mineral surfaces; the kinetics of precipitation and dissolution reactions; and the fractionation of stable isotopes. Later chapters provide a large number of fully worked calculation examples and case studies demonstrating the modeling techniques that can be applied to scientific and practical problems. Students in a variety of specialties from low-temperature geochemistry to groundwater hydrology will benefit from the wealth of information and practical applications this book has to offer.

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Metamorphic reaction rate laws and development of isograds

Mineralogical Magazine ◽

10.1180/minmag.1986.050.357.02 ◽

1986 ◽

Vol 50 (357) ◽

pp. 359-373 ◽

Cited By ~ 78

Author(s):

Antonio C. Lasaga

Keyword(s):

Diffusion Processes ◽

Relative Role ◽

Mineral Surfaces ◽

Surface Kinetics ◽

Rate Laws ◽

Careful Treatment ◽

Reaction Zones ◽

Kinetics Of ◽

And Diffusion

AbstractNew data on the kinetics of dehydration of muscovite + quartz suggest the necessity for a careful treatment of both surface kinetics and diffusion processes in metamorphic reactions. A new model is proposed that illustrates the relative role of diffusion and surface reactions in the overall metamorphic process. The rate law for the reaction at mineral surfaces derived from the experimental data is shown to be probably non-linear and similar to rate laws derived from Monte Carlo calculations. The experimental rate data is then used in a heat flow calculation to model the evolution of the muscovite isograd in the field. The position of the isograd, the temperature oversteps above equilibrium, and the width of ‘reaction zones’ are then analysed as a function of intrusion size and kinetic parameters.

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Desorption rate of glyphosate from goethite as affected by different entering ligands: hints on the desorption mechanism

Environmental Chemistry ◽

10.1071/en17004 ◽

2017 ◽

Vol 14 (5) ◽

pp. 288 ◽

Cited By ~ 3

Author(s):

Jeison M. Arroyave ◽

Carolina C. Waiman ◽

Graciela P. Zanini ◽

Wenfeng Tan ◽

Marcelo J. Avena

Keyword(s):

Desorption Kinetics ◽

Desorption Rate ◽

Mineral Surfaces ◽

Desorption Process ◽

Ligand Exchange Reaction ◽

Mineral Particles ◽

Desorption Rate Constant ◽

Desorption Mechanism ◽

Adsorption Desorption ◽

Kinetics Of

Environmental contextGlyphosate is a heavily used herbicide that is mobilised in soil and sediments through adsorption–desorption processes from the surface of mineral particles. We demonstrate that the desorption rate of glyphosate from goethite, a ubiquitous mineral, is nearly independent of the concentration and nature of the substance that is used to desorb it. The results elucidate the desorption mechanism and are relevant to understand and predict the environmental mobility of glyphosate. AbstractThe desorption kinetics of glyphosate (Gly) from goethite was studied in a flow cell using attenuated total reflectance Fourier-transform infrared spectroscopy. Because Gly forms an inner-sphere surface complex by coordinating to Fe atoms at the goethite surface, the desorption process is actually a ligand-exchange reaction, where Gly is the leaving ligand and water molecules or dissolved substances are the entering ligands. A series of possible entering ligands that can be found in nature was tested to evaluate their effect on the desorption kinetics of Gly. Contrarily to expectations, the desorption rate was quite independent of the entering ligand concentration. Moreover, the identity of this ligand (phosphate, citrate, sulfate, oxalate, EDTA, thiocyanate, humic acid, water) had only a small effect on the value of the desorption rate constant. By analogy with the reactivity of transition metal complexes in solution, it is concluded that the rate is mainly controlled by the breaking of the Fe–Gly bond, through a dissociative or a dissociative interchange mechanism. The results are relevant in understanding and predicting the environmental mobility of Gly: irrespective of the identity of the entering ligand, Gly will always desorb from iron (hydr)oxides in nature at nearly the same rate, simplifying calculations and predictions enormously. The importance of studying desorption kinetics using mineral surfaces and environmentally relevant molecules is also highlighted.

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CINÉTIQUE ET MÉCANISME DE L'HYDROLYSE ACIDE DE LA MATIÈRE ORGANIQUE D'UN SOL HUMIFÈRE DE MONTAGNE

Canadian Journal of Soil Science ◽

10.4141/cjss87-061 ◽

1987 ◽

Vol 67 (3) ◽

pp. 647-658 ◽

Cited By ~ 11

Author(s):

E. BARRIUSO ◽

J. M. PORTAL ◽

F. ANDREUX

Keyword(s):

Acid Hydrolysis ◽

Fulvic Acids ◽

Mineral Surfaces ◽

Humic And Fulvic Acids ◽

Carbon And Nitrogen ◽

Fine Clay ◽

Humification Degree ◽

The Stability ◽

Kinetics Of ◽

Stable Material

From the surface horizon of an organic-rich mountain soil, humic and fulvic acids, and organo-mineral compounds including clay and hydroxy-metal colloids, were separated and purified. Each of these fractions was hydrolyzed in 3.0 M HCl under reflux, then the reaction parameters related to the solubilization of carbon and nitrogen and to the kinetics of hydrolysis were calculated. Acid hydrolysis was interpreted as the result of two successive steps: first a rapid electrophilic attack of heteroatomic C-O and C-N bonds by protons, then a slow nucleophilic hydration of the protonated bonds. Electron delocalization in these bonds, which increased with the polycondensation degree of organic compounds, and with their adsoprtion on mineral surfaces, resulted in an increase in their stability to hydrolysis. Fulvic acids were found to be the less stable material, and lead to predominantly anionic hydrolysis products. Clay-sized humin was the most stable material and yielded mainly cationic hydrolysates. The stability to hydrolysis and the humification degree of organic matter in the fractions generally coincided, and decreased in the following order: fine clay-sized humin > alkali dispersible organo-mineral colloids > > humic acids > hydroxy-ferric organic colloids > hydroxy-aluminium organic colloids = fulvic acids. Key words: Organo-mineral complex, humic substances, acid hydrolysis, carbon, nitrogen

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Kinetics of pyrite, pyrrhotite, and chalcopyrite dissolution byAcidithiobacillus ferrooxidans

Canadian Journal of Microbiology ◽

10.1139/cjm-2016-0085 ◽

2016 ◽

Vol 62 (8) ◽

pp. 629-642 ◽

Cited By ~ 7

Author(s):

Ayse Tuba Kocaman ◽

Mustafa Cemek ◽

Katrina Jane Edwards

Keyword(s):

Acidithiobacillus Ferrooxidans ◽

Dissolution Kinetics ◽

The Other ◽

Mineral Surfaces ◽

Dissolution Rates ◽

Ion Concentrations ◽

Ph Changes ◽

Kinetics Of Dissolution ◽

Kinetics Of ◽

Number Of Cells

The main objective of this study was to investigate the dissolution kinetics of pyrite, pyrrhotite, and chalcopyrite. Crushed minerals were reacted with Acidithiobacillus ferrooxidans (25 °C). The kinetics of dissolution was investigated by monitoring pH and Fe2+and Fe3+ion concentrations in the leaching solutions. Pyrite, pyrrhotite, and chalcopyrite dissolution by A. ferrooxidans was found to be a chemically controlled process. With bacteria, the dissolution rates of the minerals increased in the order of pyrrhotite, pyrite, and chalcopyrite. The number of cells attached to mineral surfaces increased in the same order. Acidithiobacillus ferrooxidans was found to enhance the dissolution rates of the minerals. The acid-insoluble trait of pyrite and acid-soluble trait of the other 2 minerals affected the pH changes in the leaching solutions.

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