Download or read book Understanding Redox Processes in Surface Environments from Iron Oxide Transformations and Multiple Sulfur Isotope Fractionations written by Tsubasa Otake and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Redox written by J. Schüring and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: Few processes are as important for environmental geochemistry as the interplay between the oxidation and reduction of dissolved and solid species. The knowledge of the redox conditions is most important to predict the geochemical behaviour of a great number of components, the mobilities of which are directly or indirectly controlled by redox processes. The understanding of the chemical mechanisms responsible for the establishment of measurable potentials is the major key for the evaluation and sensitive interpretation of data. This book is suitable for advanced undergraduates as well as for all scientists dealing with the measurement and interpretation of redox conditions in the natural environment.
Download or read book Investigations of Surface Redox Chemistry on Environmentally Relevant Iron Oxides and Sulfides written by Elizabeth B. Cerkez and published by . This book was released on 2016 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: Important reactions in the environment often occur at the interface between a mineral surface and aqueous phase. Reactions occurring at this interface often control the uptake or release of harmful components resulting in the geochemical cycling of elements in the environment. Additionally, minerals are commonly used in the remediation of contaminated areas, where similar chemistry occurs at their interfaces. Thus, studies of the chemistry of these interfaces are essential to our understanding of complex environments. Many of these processes are controlled by electron transfer reactions between adsorbates and the mineral interface, and it is here where this research presented will concentrate. The studies in this thesis key in on redox chemistry on various environmentally relevant iron minerals, including ferrihydrite, pyrite, and amorphous iron sulfide. A large portion of this body of work is dedicated to the understanding of the surface mediated reaction between chromate (Cr(VI)) and arsenite (As(III)). Both of these species are present in the environment and are detrimental to human health. Using in- and ex-situ experiments we have monitored the coupled redox transformation of Cr(VI) and As(III) to chromite (Cr(III)) and arsenate (As(V)). Quantum mechanical modeling was used to support the experimental studies of this novel redox chemistry. The reaction was monitored in situ, using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), on the surface of the iron oxyhydroxide, ferrihydrite, at various solution pH values by following vibrational modes unique to Cr(VI), As(III), and As(V). At pH
Download or read book Aquatic Redox Chemistry written by Paul Tratnyek and published by OUP USA. This book was released on 2012-06-14 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume provides a comprehensive overview of aquatic redox chemistry through chapters contributed by many of the leading investigators in the field.
Download or read book Iron Mineral Transformations and Electron Transfer Reactions in Redox Dynamic Environments written by Elizabeth J. Tomaszewski and published by . This book was released on 2017 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to the abundance and redox potential of iron (Fe), the solubility and oxidation state of trace metals may be strongly influenced by redox reactions with Fe minerals. The ability of a Fe mineral to participate in electron transfer with trace metals, such as chromium (Cr), is dependent on a variety of properties and processes. These include, but are not limited to, surface area, mineral stoichiometry, and geochemical conditions, such as redox potential. This dissertation work examines Fe mineral transformations and electron transfer reactions with Cr(VI) under varying redox conditions. In the second chapter, the mineralogical transformations of ferrihydrite ((Fe10O14(OH)2)) are investigated during rapid, abiotic redox oscillations, at different concentrations of dissolved Fe(II). The stoichiometry of the secondary mineral magnetite (Fe3O4) increases overall throughout redox oscillations, despite repeated exposure to oxygen. This work demonstrates structural Fe(II) in Fe minerals may not be oxidized in the presence of oxygen and could be a source of electrons in redox dynamic environments. In the third chapter, goethite ([alpha]-FeOOH) is exposed to varying numbers of abiotic redox cycles (e.g., 1, 2, 3, or 4) and subsequently reacted with Cr(VI). The reduction of Cr(VI) to Cr(III) is observed, demonstrating that Fe(II) substituted within the goethite lattice during anoxic periods is not only preserved during oxic periods but also available for electron transfer. Regardless of the number of redox cycles to which goethite is exposed Cr consistently is associated with the (100) crystallographic face, a predicted site of electron conduction. Finally, the fourth chapter examines the electron transfer between Cr(VI) and the reduced quinone species, AH2DS in the presence and absence of goethite at three different ratios of AH2DS:Cr(VI). Goethite inhibits of the extent of Cr(VI) reduction to Cr(III) most significantly at the highest ratio of AH2DS:Cr(VI) investigated. Possible production of semi-quinone radical species may limit electron transfer and decrease the percent yields of Fe(II) and Cr(III). Additionally, solid phase characterization of Cr confirms the formation of Cr(OH)3 phases. Understanding abiotic electron transfer reactions that occur in systems with multiple redox active species is important to elucidate the contribution of abiotic redox reactions to biogeochemical cycling in natural soils.
Download or read book Redox Reactions and Phase Transformation Processes at Iron Mineral Surfaces Studied by Compound Specific Isotope Analysis written by Anke Buchholz and published by . This book was released on 2009 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Explaining Reaction Rates Between Iron Oxide Associated Ferrous Iron and Nitrobenzene written by Sydney Stewart and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Redox reactions have important implications for contaminant fate and transport in the environment, as they can lead to transformations that affect chemical mobility, toxicity, and bioavailability. Many classes of contaminants can be reduced by ferrous iron (Fe2+) associated with iron oxides in subsurface anoxic environments. These include contaminants containing nitroaromatic functional groups, which are common due to their widespread release into the environment as pesticides and explosives. Understanding the transformations of these chemicals is essential for determining how to remediate contaminated sites. Nitrobenzene is a useful proxy for nitroaromatic contaminants because it provides a relatively simple model system that can give insight into how more complex or less reactive chemicals are transformed in the environment.While the reduced products that form as a result of these reactions are often well characterized, the rates at which they occur are typically difficult to predict. Measured values from well-controlled laboratory studies frequently vary by orders of magnitude. In principle, these rates can be described and possibly estimated by the thermodynamic driving force of the reaction (e.g., reduction potential values for the reductant and oxidant), but demonstrating this has been difficult to test due to the difficulty in obtaining meaningful and reliable reduction potential values for iron redox couples. Recently, that limitation was overcome using mediated potentiometry, a technique that has led to a quantitative understanding of the thermodynamics of Fe2+-Fe oxy(hydr)oxide redox couples. Using mediated potentiometry, reduction potentials for these redox couples can be measured, predicted, and controlled.The ability to determine reduction potential of the Fe2+-Fe oxide couple introduces the opportunity to evaluate the relationship between reaction rates and thermodynamic parameters. In this study, I hypothesized that reduction potentials could be used to explain redox reaction rates between nitrobenzene and the Fe2+-goethite (-FeOOH) couple. This was tested by measuring nitrobenzene reduction rates as a function of solution pH, Fe2+ concentration, and goethite loading. With these results, the reduction potential of the Fe2+-goethite couple was correlated with the reaction rate constant over all solution conditions using a linear free energy relationship (LFER). The reduction of nitrobenzene was rate-limited by the first electron transfer and the first proton transfer steps, which appeared to be coupled. The best correlation for the data was achieved by normalizing the reaction rate constant to surface area of the oxide, implying nitrobenzene was reduced at the oxide surface by delocalized electrons within the solid, rather than directly by discrete oxide-associated Fe2+ sites.This LFER was further used to determine how changing the goethite particle size, and hence its thermodynamic properties, influence nitrobenzene reduction rates. From experiments with nanogoethite-associated Fe2+, it was found that the surface area normalized reaction rates for nitrobenzene with the Fe2+-nanogoethite couple were better described by the reduction potential of micron-sized goethite than that of nanogoethite. This data suggests that reduction rates by goethite-associated Fe2+ kinetically depend on the surface area of the oxide, but the thermodynamic driving force of the reaction only depends on the standard reduction potential of bulk goethite. These conclusions were further supported by comparisons to data in the literature for goethite and hematite-catalyzed reactions with substituted nitrobenzenes. Previously reported reaction rates correlated well with the LFER developed in this study.These results corroborate the hypothesis that redox reactions involving Fe2+-Fe oxy(hydr)oxide couples could be explained by growth of the oxy(hydr)oxide crystals. The reduction potential of this reaction describes the thermodynamic driving force of nitroaromatic reduction, and the reaction rate is related to the surface area of the oxides. Ultimately, this work provides insight into the mechanisms of important environmental transformations, and can lead to improved predictive models for contaminant reduction rates as a function of geochemical conditions.
Download or read book The Reactivity and Isotopic Fractionation of Fe bearing Minerals During Sulfidation written by Alison McAnena and published by . This book was released on 2011 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Environmental Soil Remediation and Rehabilitation written by Eric D. van Hullebusch and published by Springer Nature. This book was released on 2020-04-22 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive overview of innovative remediation techniques and strategies for soils contaminated by heavy metals or organic compounds (e.g. petroleum hydrocarbons, NAPLs and chlorinated organic compounds). It discusses various novel chemical remediation approaches (in-situ and ex-situ) used alone and in combination with physical and/or thermal treatment. Further, it addresses the recovery of NAPLs, reuse of leaching solutions, and in-situ chemical reduction and oxidation, and explores the chemical enhancement of physical NAPLs recovery from both practical and theoretical perspectives. Also presenting the state-of-the-art in waste-assisted bioremediation to improve soil quality and the remediation of petroleum hydrocarbons, the book is a valuable resource for students, researchers and R&D professionals in industry engaged in the treatment of contaminated soils.
Download or read book The Biogeochemistry of Submerged Soils written by Guy Kirk and published by John Wiley & Sons. This book was released on 2004-06-25 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Submerged soils and the wetlands they support are of huge practical importance: in global element cycles, as centres of biodiversity, in global food production. They are also uniquely interesting scientifically because of their peculiar biogeochemistry and the adaptations of plants and microbes to it. This book describes the physical, chemical and biological processes operating in submerged soils and governing their properties. It describes the transport processes controlling the fluxes of gases and solutes through the soil; the interchange of solutes between solid, liquid and gas phases; reduction and oxidation processes; biological processes in the soil and overlying water; and processes in the roots and rhizospheres of wetland plants. The dynamics of nutrients, toxins, pollutants and trace gases are then discussed in terms of these processes and in relation to wetland productivity and global element cycles. Written by a renowned expert in the field, this work will be invaluable to earth, environmental and agricultural scientists concerned with natural or man-made wetlands, and to advanced undergraduate and graduate studen ts of these topics.
Download or read book Nanomaterials in the Environment written by Satinder Kaur Brar and published by ASCE Press. This book was released on 2015-10-01 with total page 642 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text presents the most current knowledge on the environmental impact of materials and products developed using nanotechnology. Although nanomaterials are revolutionising electronics, medicine, transportation and many other industries, they pose risks to living beings and ecosystems that are barely understood. Leading researchers here consider the science of nanomaterials, their behaviour in the environment, risk assessment and toxicology, and the future of nanomaterials.
Download or read book Using Geochemical Data written by Hugh Rollinson and published by Cambridge University Press. This book was released on 2021-05-06 with total page 359 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook is a complete rewrite, and expansion of Hugh Rollinson's highly successful 1993 book Using Geochemical Data: Evaluation, Presentation, Interpretation. Rollinson and Pease's new book covers the explosion in geochemical thinking over the past three decades, as new instruments and techniques have come online. It provides a comprehensive overview of how modern geochemical data are used in the understanding of geological and petrological processes. It covers major element, trace element, and radiogenic and stable isotope geochemistry. It explains the potential of many geochemical techniques, provides examples of their application, and emphasizes how to interpret the resulting data. Additional topics covered include the critical statistical analysis of geochemical data, current geochemical techniques, effective display of geochemical data, and the application of data in problem solving and identifying petrogenetic processes within a geological context. It will be invaluable for all graduate students, researchers, and professionals using geochemical techniques.
Download or read book Iron Oxides in the Laboratory written by Udo Schwertmann and published by Wiley-VCH. This book was released on 1991-03-06 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents reliable, well-tested, up-to-date methods of synthesizing the major iron oxides. Such a collection is invaluable since iron oxides play an important role in numerous disciplines, including chemistry, soil science, medicine, corrosion science and aquatic and environmental chemistry. The emphasis is on techniques and apparatus that are readily accessible to the scientist. For students, the sections dealing with potential sources of error should prove extremely useful. Techniques for iron oxide characterization are also described in detail. Special Feature: color plates illustrating how the color of iron oxides varies with crystal structure, particle size, and metal substitution.
Download or read book The Benthic Boundary Layer written by Bernard P. Boudreau and published by Oxford University Press. This book was released on 2001-03-22 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt: The benthic boundary layer is the zone of water and sediment immediately adjacent to the bottom of a sea, lake, or river. This zone is of considerable interest to biologists, geochemists, sedimentologists, and engineers because of very strong gradients of energy, dissolved and solid chemical components, suspended matter, and the number of organisms that live there. It is, for example, the sink for anthropogenic substances and the home of microscopic plant life that provides the nutrients that determine fish populations--and ultimately the size of the fisheries. This book of original chapters edited by Professors Boudreau and Jorgensen, both leading researchers in the field, will meet the need for an up-to-date, definitive text/reference on measurements, techniques, and models for transport and biochemical processes in the benthic boundary layer. Each chapter provides a comprehensive review of a selected field, with illustrated examples from the authors' own work. The book will appeal to professionals and researchers in marine biology, marine chemistry, marine engineering, and sedimentology.
Download or read book Past and Present Water Column Anoxia written by Lev N. Neretin and published by Springer Science & Business Media. This book was released on 2006 with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ehrlich s Geomicrobiology written by Henry Lutz Ehrlich and published by CRC Press. This book was released on 2015-10-15 with total page 643 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in geomicrobiology have progressed at an accelerated pace in recent years. Ehrlich's Geomicrobiology, Sixth Edition surveys various aspects of the field, including the microbial role in elemental cycling and in the formation and degradation of minerals and fossil fuels. Unlike the fifth edition, the sixth includes many expert contributors
Download or read book Sulfur Biogeochemistry written by Jan P. Amend and published by Geological Society of America. This book was released on 2004 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:
