scholarly journals Electrochemical and Structural Modifications of Humic Acids in Aerobically and Anaerobically Incubated Peat

Land ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1189
Author(s):  
Carlo Bravo ◽  
Rosanna Toniolo ◽  
Marco Contin ◽  
Maria De Nobili
Keyword(s):  
Biological Activity ◽  
Humic Acids ◽  
Redox Properties ◽  
Structural Modifications ◽  
First Order ◽  
Greenhouse Gases Emissions ◽  
Mediated Electrochemical Oxidation ◽  
Organic Tea ◽  
Electron Transfer Kinetic

Exposure to oxygen and aerobic biological activity during drought periods alters the availability of terminal electron acceptors (TEA) in the peat catotelm layer. We investigated the changes in the electrochemical and chemical characteristics of humic acids (HA) induced by subjecting air-dried sphagnum peat to biological oxidation or reduction during a 90-day incubation experiment. Structural modifications of HAs from anaerobically (HAred) and aerobically (HAox) incubated peat were investigated by ATR-FTIR, UV–vis, and EEM fluorescence spectroscopy. Number and strength of acid groups were characterized by titration, while changes in redox properties were characterized by cyclic voltammetry and quantified by coulometry with mediated electrochemical oxidation (MEO). Exposure to oxygen had small effects, but compared to anaerobic incubation, decreased by 20% the capacity of HA to reduce the radical ion of 2,2′-Azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS●−), passing from 2.77 ± 0.13 mmole- gHA−1 in HAred to 2.21 ± 0.10 mmole- gHA−1 in HAox. Pseudo-first-order electron transfer kinetic constants were 13.3 ± 1.2 s−1 for HAox and 16.7 ± 1.4 s−1 for HAred. Alterations in the hydrological status of the catotelm have minor effects on the actual in situ availability of organic TEA, but if coupled to intensified biological activity they may result in significant variations of greenhouse gases emissions.

Modified ferron assay for speciation characterization of hydrolyzed Al(III): a precise k value based judgment

2009 ◽  
Vol 59 (4) ◽  
pp. 823-832 ◽  
Author(s):  
Ye Changqing ◽  
Wang Dongsheng ◽  
Wu Xiaohong ◽  
Qu Jiuhui ◽  
John Gregory
Keyword(s):  
Kinetic Constant ◽  
Nonlinear Least Squares ◽  
Precise Determination ◽  
K Value ◽  
First Order ◽  
First Order Kinetics ◽  
Parallel Reactions

The speciation of Al-OH complexes in terms of Ala, Alb and Alc could be achieved by traditional ferron assay and Alb is generally considered as Al13, however, the inherent correlation between them remains an enigma. This paper presents a modified ferron assay to get precise determination of Al13 using nonlinear least squares analysis, and to clarify the correlation between Alb and Al13. Two parallel reactions conforming to pseudo-first-order kinetics can simulate the complicate reactions between polynuclear complexes and ferron successfully. Four types of experimental kinetic constant (k value) of Al-OH complexes can be observed by this method when investigating three typical aluminium solutions. Comparing with the results of 27Al NMR, the species with moderate kinetics around 0.001 s−1 can be confirmed to resemble to Al13 polycation. The other types of kinetics are also well-regulated in partially neutralized aluminium solutions with various OH/Al ratios (b values) in the range 0 ∼ 2.5. It would provide potential means to trace the in-situ formation of Al13 in dilute solutions such as coagulation with Al-based coagulants

Inorganic mixed phase templated by a fatty acid monolayer at the air–water interface: the Mn and Mg case

2018 ◽  
Vol 20 (9) ◽  
pp. 6629-6637 ◽  
Author(s):  
Alae El Haitami ◽  
Michel Goldmann ◽  
Philippe Fontaine ◽  
Marie-Claude Fauré ◽  
Sophie Cantin
Keyword(s):  
Grazing Incidence ◽  
Water Interface ◽  
X Ray Diffraction ◽  
Inorganic Layer ◽  
X Ray ◽  
First Order ◽  
First Order Phase Transition ◽  
Air Water Interface ◽  
First Order Phase

A first-order phase transition with a peculiar feature is evidenced by means of in situ grazing incidence X-ray diffraction in the 2D organic phase-mediated nucleation of an inorganic layer.

In-Situ Diffraction Studies of Gas Storage Materials on a Laboratory X-Ray System

2013 ◽  
Vol 1544 ◽  
Author(s):  
Marco Sommariva ◽  
Harald van Weeren ◽  
Olga Narygina ◽  
Jan-André Gertenbach ◽  
Christian Resch ◽  
...  
Keyword(s):  
Large Scale ◽  
Fossil Fuels ◽  
Reaction Chamber ◽  
Hydrogen Gas ◽  
Gas Pressure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural Modifications ◽  
Model Studies

ABSTRACTThe sorption processes for hydrogen and carbon dioxide are of considerable, and growing interest, particularly due to their relevance to a society that seeks to replace fossil fuels with a more sustainable energy source. X-ray diffraction allows a unique perspective for studying structural modifications and reaction mechanisms that occur when gas and solid interact. The fundamental challenge associated with such a study is that experiments are conducted while the solid sample is held under a gas pressure. To date in-situ high gas pressure studies of this nature have typically been undertaken at large-scale facilities such as synchrotrons or on dedicated laboratory instruments. Here we report high-pressure XRD studies carried out on a multi-purpose diffractometer. To demonstrate the suitability of the equipment, two model studies were carried out, firstly the reversible hydrogen cycling over LaNi5, and secondly the structural change that occurs during the decomposition of ammonia borane that results in the generation of hydrogen gas in the reaction chamber. The results have been finally compared to the literature. The study has been made possible by the combination of rapid X-ray detectors with a reaction chamber capable of withstanding gas pressures up to 100 bar and temperatures up to 900 °C.

scholarly journals An Electrochemical Process Comparison of As(III) in Simulated Groundwater at Low Voltage in Mixed and Divided Electrolytic Cells

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1126 ◽  
Author(s):  
Yanyan Qin ◽  
Yanping Cui ◽  
Lidan Lei ◽  
Ya Gao ◽  
Zhengwei Zhou ◽  
...  
Keyword(s):  
Low Voltage ◽  
Electrochemical Process ◽  
First Order ◽  
Electrolytic Cells ◽  
Process Comparison ◽  
First Order Kinetics ◽  
Simulated Groundwater ◽  
High Arsenic ◽  
High Arsenic Groundwater

A relatively low voltage can be favor of e- transfer and peroxide generation from dominant 2e--reduction of O2 on carbon materials as cathode, with low energy loss. In this study the conversion of As(III) in simulated high arsenic groundwater at low voltage was compared in a mixed and a anode–cathode separated electrolytic system. With applied voltages (the potential difference between cathode and anode) from 0.1 V to 0.8 V, As(III) was found to be efficiently converted to As(V) in the mixed electrolytic cells and in separated anodic cells. The complete oxidation of As(III) to As(V) at 0.1–0.8 V was also achieved on graphite in divided cathodic cells which could be long-running. The As(III) conversion process in mixed electrolytic cells, anodic cells and cathodic cells all conformed to the pseudo first-order kinetics equation. The energy consumed by As(III) conversion was decreased as the applied voltage declined. Low voltage electrolysis is of great significance for saving energy consumption and improving the current efficiency and can be applied to in-situ electrochemical pre-oxidation for As(III) in high arsenic groundwater.

scholarly journals British Museum Natural Radiocarbon Measurements XXII

Radiocarbon ◽  
1991 ◽  
Vol 33 (1) ◽  
pp. 51-68 ◽  
Author(s):  
Janet Ambers ◽  
Keith Matthews ◽  
Sheridan Bowman
Keyword(s):  
Humic Acid ◽  
Humic Acids ◽  
Chlorine Dioxide ◽  
Liquid Scintillation Counting ◽  
Liquid Scintillation ◽  
British Museum ◽  
Scintillation Counting ◽  
Dilute Acid ◽  
Organic Fraction

The following list consists of dates, obtained by liquid scintillation counting of benzene, for archaeologic samples mostly measured between June 1987 and October 1989.Charcoal and grain samples were pretreated with 1M HCl followed by washing in water and, where considered necessary, with dilute alkali for the removal of humic acids. Wood samples were treated either in the same way, or, where large enough, were reduced to cellulose by the action of chlorine dioxide produced in situ. All antler and bone samples were treated with cold dilute acid. The term ‘collagen’ is used throughout to mean the acid insoluble organic fraction produced by this treatment. Peat samples were treated with dilute acid and alkali to separate the humin and humic acid fractions, which were dated individually.

scholarly journals Muskrat (Ondatra zibethicus) interference with aquatic invertebrate traps

2014 ◽  
Vol 128 (2) ◽  
pp. 200 ◽  
Author(s):  
Michael C. Cavallaro ◽  
Anson R. Main ◽  
Christy A. Morrissey
Keyword(s):  
Aquatic Insect ◽  
Aquatic Invertebrate ◽  
Ondatra Zibethicus ◽  
Local Fauna ◽  
Insect Emergence ◽  
Litter Bags ◽  
Structural Modifications ◽  
Aquatic Insect Emergence ◽  
Emergence Traps

In field biology, interactions between wildlife and in situ equipment occur often. These interactions have the potential to induce a variety of behaviours in local fauna. Here, we note the destructive behaviour exhibited by the Muskrat (Ondatra zibethicus) following deployment of aquatic invertebrate traps for research purposes at 12 wetlands located in central Saskatchewan. Of 24 aquatic insect emergence traps used on seven wetlands in our study, 14 (58%) required recurring repairs. In addition, on several occasions, leaf litter bags and their anchoring stakes were torn or chewed. The recurring damage took place in wetlands with Muskrat lodges. We recommend structural modifications to aquatic invertebrate traps in wetland complexes densely inhabited by Muskrats and other semi-aquatic rodents.

Xps and Voltammetry Studies of Redox Behavior of Lacrl1− NixO3 Electrodes

1998 ◽  
Vol 548 ◽  
Author(s):  
Greg Vovk ◽  
Xiaohua Chen ◽  
Charles A. Mims
Keyword(s):  
Redox State ◽  
Electrochemical Cell ◽  
High Vacuum ◽  
Adsorption Properties ◽  
Binding Energies ◽  
Redox Properties ◽  
Ultra High Vacuum ◽  
Redox Behavior ◽  
Heated Sample

ABSTRACTAn in-situ XPS and voltammetry investigation of the redox properties of LaCrj1-xNixO3(x = 0.4, 1) was carried out by incorporating the materials as one electrode in an electrochemical cell (LaCr1xNixO3|YSZ|Pd:PdO), which was directly mounted on a heated sample stage in an ultra high vacuum (UHV) chamber. Under a 0.7V cathodic bias, the perovskites reduce from formal oxidation state of Ni3+ to Ni2+. This reduction is accompanied by wholesale shifts of the Cr and O core level binding energies, in keeping with the delocalized electronic states in the material. The adsorption properties of the surfaces are affected by the redox state of the surfaces; increased CO2adsorption is observed on the reduced (and therefore more basic) surface.

scholarly journals In Situ TEM Observation of Thermally-Induced First-Order Magnetic Transition in Itinerant-Electron Metamagnetic La(FexSi1−x)13 Compounds

2005 ◽  
Vol 46 (8) ◽  
pp. 1764-1767 ◽  
Author(s):  
Naoyuki Kawamoto ◽  
Yasukazu Murakami ◽  
Daisuke Shindo ◽  
Shun Fujieda ◽  
Asaya Fujita ◽  
...  
Keyword(s):  
Magnetic Transition ◽  
Itinerant Electron ◽  
Thermally Induced ◽  
First Order
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