Download or read book Metal Ion Influence on Chromium Oxidation by Manganese Dioxide written by Scott Edward Fendorf and published by . This book was released on 1990 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book INTERACTIONS BETWEEN METAL OXIDES AND OR NATURAL ORGANIC MATTER AND THEIR INFLUENCE ON THE OXIDATIVE REACTIVITY OF MANGANESE DIOXIDE written by Saru Taujale and published by . This book was released on 2015 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mn oxides have high redox potentials and are known to be very reactive, rendering many contaminants susceptible to degradation via oxidation. Although Mn oxides typically occur as mixtures with other metal oxides (e.g., Fe, Al, and Si oxides) and natural organic matter (NOM) in soils and aquatic environments, most studies to date have studied the reactivity of Mn oxides as a single oxide system. This study, for the first time, examined the effect of representative metal oxides (Al2O3, SiO2, TiO2, and Fe oxides) and NOM or NOM-model compounds (Aldrich humic acid (AHA), Leonardite humic acid (LHA), pyromellitic acid (PA) and alginate) on the oxidative reactivity of MnO2, as quantified by the oxidation kinetics of triclosan (a widely used phenolic antibacterial agent) as a probe compound. The study also examined the effect of soluble metal ions released from the oxide surfaces on MnO2 reactivity. In binary oxide mixtures, Al2O3 decreased the reactivity of MnO2 as a result of both heteroaggregation and complexation of soluble Al ions with MnO2. At pH 5, the surface charge of MnO2 is negative while that of Al2O3 is positive resulting in intensive heteroaggregation between the two oxides. Up to 3.15 mM of soluble Al ions were detected in the supernatant of 10 g/L of Al2O3 at pH 5.0 whereas the soluble Al concentration was 0.76 mM in the mixed Al2O3 + MnO2 system at the same pH. The lower amount of soluble Al in the latter system is the result of Al ion adsorption by MnO2. The experiments with the addition of 0.001 to 0.1 mM Al3+ to MnO2 suspension indicated the triclosan oxidation rate constant decreased from 0.24 to 0.03 h-1 due to surface complexation. Fe oxides which are also negatively charged at pH 5 inhibited the reactivity of MnO2 through heteroaggregation. The concentration of soluble Fe(III) ions ( 4 mg-TOC/L or [alginate/PA] > 10 mg/L, a lower extent of heteroaggregation was also observed due to the negatively charged surfaces for all oxides. Similar effects on aggregation and MnO2 reactivity as discussed above were observed for ternary MnO2-Al2O3-NOM systems. HAs, particularly at high concentrations (2.0 to 12.5 mg-C/L), alleviated the effect of soluble Al ions on MnO2 reactivity as a result of the formation of soluble Al-HA complexes. Alginate and PA, however, did not form soluble complexes with Al ions so they did not affect the effect of Al ions on MnO2 reactivity. Despite the above observations, the amount of Al ions dissolved in MnO2+Al2O3+NOM mixtures was too low, as a result of NOMs adsorption on the surface to passivate oxide dissolution, to have a major impact on MnO2 reactivity. In conclusion, this study provided, for the first time, a systematical understanding of the redox activity of MnO2 in complex model systems. With this new knowledge, the gap between single oxide systems and complex environmental systems is much narrower so that it is possible to have a more accurate prediction of the fate of contaminants in the environment.
Download or read book Oxidation of Chromium by Manganese Oxide written by Michael James Takacs and published by . This book was released on 1988 with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Coupling of Oxidation reduction Reactions of Chromium Iron and Manganese written by Chao Pan (Environmental engineer) and published by . This book was released on 2017 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: Both within the United States and internationally, hexavalent chromium (Cr(VI)) is a contaminant of concern in drinking water supplies. The U.S. Environmental Protection Agency is considering a Cr(VI)-specific standard. Thus improved technologies for Cr(VI) removal in drinking water are needed. Iron electrocoagulation for Cr(VI) removal was examined at conditions directly relevant to drinking water treatment, and humic acid (HA) affects the performance of electrocoagulation in multiple ways. The success of the chromium treatment or remediation also relies on the stability of the Cr(III)-containing solids with respect to reoxidation under groundwater conditions. Manganese is ubiquitous in aquatic and terrestrial environments, and the redox cycling of manganese may significantly impact the fate and transport of chromium. Coupling of redox reactions of chromium, iron and manganese involves multiple interaction pathways that occur in the aqueous phase as well as at solid-water interfaces. A mechanistic and quantitative understanding of these processes is needed to establish input parameters for kinetic and transport models and to enable decision-making for chromium treatment strategies.Iron electrocoagulation (EC) is a technology that can successfully achieve low concentrations of Cr(VI) in treated drinking water. In our research we have applied iron electrocoagulation (EC) with iron serving as the sacrificial anode to treat simulated drinking water solutions. Experiments have evaluated the effects of pH, dissolved oxygen, and common anions on Cr(VI) removal during batch EC treatment. In addition, the presence of humic acid (HA) inhibited the rate of Cr(VI) removal in electrocoagulation, with slower Cr(VI) removal at higher pH. This is due to dissolved oxygen competing with Cr(VI) for the oxidation of Fe(II) released from the anode. As determined using dynamic light scattering and wet chemistry experiments, the presence of HA resulted in the formation of Cr(III)-Fe(III)-HA colloids during electrocoagulation, which is difficult to remove in following water treatment steps of sedimentation and granular media filtration. Characterization of the solids by X-ray diffraction indicates that the iron oxides produced are lepidocrocite at pH 8, with more ferrihydrite in the presence of HA.Building on previous knowledge of MnO2 as an oxidant for Cr-containing solids, we systematically evaluated the rates and products of the oxidation of Cr(III) in iron oxides by MnO2. We found that Cr(III) dissolution from CrxFe1-x(OH)3 greatly influenced the Cr(VI) production rates. A multi-chamber reactor was used to assess the role of solid-solid mixing in CrxFe1-x(OH)3-MnO2 interactions. A dialysis membrane divided the reactor into two chambers, eliminating the possibility of direct contact of the solids in each chamber but allowing dissolved species to diffuse across the membrane. The Cr(VI) production rate was much lower in multi-chamber experiments (CrxFe1-x(OH)3||MnO2) than in completely mixed batch experiments under the same condition, indicating that the redox interaction is greatly accelerated by mixing of the two solids. The model was first established to predict Cr(VI) release in Cr(OH)3||MnO2 multichamber experiments, as dissolved Cr(III) concentration in equilibrium with Cr(OH)3 is higher at low pH and it’s easy to observe the behavior of Cr(VI) dynamics with more Cr(VI) generation. While solid phase Mn(IV) is well known oxidants of Cr(III)-containing solids, the localized oxidation of adsorbed Mn(II) by dissolved oxygen can also promote the oxidation of Cr(III) contained within CrxFe1-x(OH)3. The promotional effects was likely due to Mn redox cycling in which oxidized forms of Mn species were generated as oxidants of CrxFe1-x(OH)3 that were more potent than O2.
Download or read book Chemical Processes in Marine Environments written by Antonio Gianguzza and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 446 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses recent developments in the study of chemical processes and equilibria in the marine environment and in the air/water and water/sediment interfaces. The chemical cycle of carbon as well as the effect of organic substances on the speciation and distribution of inorganic and organometallic substances are extensively discussed. Much of the recent progress in the area is the direct result of advanced analytical technologies and chemometric applications which are highlighted in the book.
Download or read book Monitored Natural Attenuation of Inorganic Contaminants in Ground Water written by and published by . This book was released on 2007 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: V.3 ... consists of individual chapters that describe 1) the conceptual background for radionuclides, including tritium, radon, strontium, technetium, uranium, iodine, radium, thorium, cesium, plutonium-americium and 2) data requirements to be met during site characterization.
Download or read book Mechanism of the Oxidation of Nickel and Chromium Alloys written by D. V. Ignatov and published by . This book was released on 1961 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanisms of Oxidation by Metal Ions written by Denis Benson and published by Elsevier Science & Technology. This book was released on 1976 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Oxidation of Organic Compounds by Permanganate Ion and Hexavalent Chromium written by Donald G. Lee and published by . This book was released on 1980 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Reviews of Environmental Contamination and Toxicology written by George Ware and published by Springer Science & Business Media. This book was released on 2006-06-01 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reviews of Environmental Contamination and Toxicology attempts to provide concise, critical reviews of timely advances, philosophy, and significant areas of accomplished or needed endeavor in the total field of xenobiotics in any segment of the environment, as well as toxicological implications.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Clay Science written by and published by . This book was released on 1996 with total page 614 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Behavior of Metals in Soils written by Joan E. McLean and published by . This book was released on 1992 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Agronomy Abstracts written by and published by . This book was released on 1990 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: Includes abstracts of the annual meetings of the American Society of Agronomy; Soil Science Society of America; Crop Science Society of America ( - of its Agronomic Education Division).
Download or read book Immunoassay written by Eleftherios P. Diamandis and published by Academic Press. This book was released on 1996-06-21 with total page 613 pages. Available in PDF, EPUB and Kindle. Book excerpt: Immunoassays are among the most powerful and sensitive technologies now available for patient diagnosis and monitoring. This book is an indispensable guide to information on the theory and practice of immunoassays. It discusses the scientific basis of these technologies in a logical, organized, and heuristic manner and provides protocols for specific assays. The contents of this unique book are balanced among theory, practical issues, quality control, automation, and subspecialty areas, making it ideal for health science students, laboratory scientists, and clinicians. Presents up-to-date information Provides extensive cross-referencing Covers theory and practice in full detail Written by leading authorities
Download or read book Manganese in Soils and Plants written by R.D. Graham and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sixty years ago at the Waite Agricultural Research Institute, G. Samuel, a plant pathologist, and C. S. Piper, a chemist, published their conclusion that the cause of roadside take-all, a disease of oats, was manganese deficiency. This report, together with the concurrent and independent studies of W. M. Carne in Western Australia were the first records of manganese deficiency in Australia and came only six years after McHargue's paper which is generally accepted as the final proof of the essentiality of this element. There must have been a few doubts for some people at the time, however, as the CAB publication, 'The Minor Elements of the Soil' (1940) expressed the view that further evidence to this effect was provided by Samuel and Piper. Their historic contributions are recognised by the International Symposium on Manganese in Soils and Plants as it meets on the site of their early labours to celebrate the 60th anniversary. This year Australians also acknowledge 200 years of European settlement in this country and so the Symposium is both a Bicentennial and a diamond jubilee event which recognises the impact of trace elements on agricultural development in Australia. In a broader sense, a symposium such as this celebrates, as it reviews, the efforts of all who over the ages have contributed to our knowledge of manganese in soils and plants.
Download or read book Corrosion Science and Technology Second Edition written by David E.J. Talbot and published by CRC Press. This book was released on 2007-06-07 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt: Despite their efforts, industries continue to lose millions of dollars every year to the destructive effects of corrosion on both structures and equipment. A large part of the problem is that diagnosing its causes and developing strategies to avoid corrosion depend on the application of principles drawn from a broad spectrum of physical sciences not typically encountered in engineering and other technical disciplines associated with industrial production. While continuing to fully explain the basic principles needed to understand corrosion science, this new edition of Corrosion Science and Technology has been updated and expanded to present the very latest technologies and strategies for limiting costly metal degradation caused by corrosion. Written by respected experts who possess an understanding of the sciences involved as well as experience with the development of corrosion control methods, this volume describes the chemistry, electrochemistry, physics, and metallurgy of various types of metals, and evaluates numerous protection measures and surface treatments. New to the Second Edition • New chapters that examine the corrosion resistance of copper, nickel, titanium, and their respective alloys • An entire chapter devoted to the expanded discussion of cathodic protection by impressed current and sacrificial anodes • Extended coverage of the equipment used in the medicine, power generation, and marine environments • Additional case histories and recently employed real-world applications Exploring corrosion control methods used in an expanded variety of commercial enterprises including aviation, automobile manufacturing, food processing, and building construction, this practical guide presents proven and cost-effective methods that industrial engineers can call upon to better protect material assets.
