Redox chemistry of CeO2 nanoparticles in aquatic systems containing Cr(vi)(aq) and Fe2+ ions

2019 ◽  
Vol 6 (7) ◽  
pp. 2269-2280
Author(s):  
Jessica R. Ray ◽  
Xuanhao Wu ◽  
Chelsea W. Neil ◽  
Haesung Jung ◽  
Zhichao Li ◽  
...  
Keyword(s):  
Surface Chemistry ◽  
Redox Chemistry ◽  
Industrial Applications ◽  
Active Species ◽  
Ceo2 Nanoparticles ◽  
Aquatic Systems ◽  
Aquatic Environments ◽  
Catalytic Activities ◽  
Redox Active

CeO2 nanoparticles are extensively used in industrial applications owing to their high redox-catalytic activities and, as a result, may appear in aquatic environments where they undergo significant surface chemistry transformation with other redox-active species.

Computational Study on Compound I Redox-Active Species in Horseradish Peroxydase Enzyme: Conformational Fluctuations and Solvation Effects

2010 ◽  
Vol 114 (20) ◽  
pp. 6817-6824 ◽  
Author(s):  
Costantino Zazza ◽  
Amedeo Palma ◽  
Nico Sanna ◽  
Simone Tatoli ◽  
Massimiliano Aschi
Keyword(s):  
Computational Study ◽  
Active Species ◽  
Compound I ◽  
Solvation Effects ◽  
Redox Active

scholarly journals Morphological and Elemental Investigations on Co–Fe–B–O Thin Films Deposited by Pulsed Laser Deposition for Alkaline Water Oxidation: Charge Exchange Efficiency as the Prevailing Factor in Comparison with the Adsorption Process

2021 ◽  
Author(s):  
Y. Popat ◽  
M. Orlandi ◽  
S. Gupta ◽  
N. Bazzanella ◽  
S. Pillai ◽  
...  
Keyword(s):  
Pulsed Laser Deposition ◽  
Water Oxidation ◽  
Active Sites ◽  
High Surface ◽  
Pulsed Laser ◽  
Industrial Applications ◽  
Active Species ◽  
Laser Deposition ◽  
Core Shell ◽  
Adsorption Sites

Abstract Mixed transition-metals oxide electrocatalysts have shown huge potential for electrochemical water oxidation due to their earth abundance, low cost and excellent electrocatalytic activity. Here we present Co–Fe–B–O coatings as oxygen evolution catalyst synthesized by Pulsed Laser Deposition (PLD) which provided flexibility to investigate the effect of morphology and structural transformation on the catalytic activity. As an unusual behaviour, nanomorphology of 3D-urchin-like particles assembled with crystallized CoFe2O4 nanowires, acquiring high surface area, displayed inferior performance as compared to core–shell particles with partially crystalline shell containing boron. The best electrochemical activity towards water oxidation in alkaline medium with an overpotential of 315 mV at 10 mA/cm2 along with a Tafel slope of 31.5 mV/dec was recorded with core–shell particle morphology. Systematic comparison with control samples highlighted the role of all the elements, with Co being the active element, boron prevents the complete oxidation of Co to form Co3+ active species (CoOOH), while Fe assists in reducing Co3+ to Co2+ so that these species are regenerated in the successive cycles. Thorough observation of results also indicates that the activity of the active sites play a dominating role in determining the performance of the electrocatalyst over the number of adsorption sites. The synthesized Co–Fe–B–O coatings displayed good stability and recyclability thereby showcasing potential for industrial applications. Graphic Abstract

Using sediment cores to establish targets for the remediation of aquatic environments

2015 ◽  
Vol 73 (3) ◽  
pp. 628-635 ◽  
Author(s):  
Anna Lintern ◽  
Marion Anderson ◽  
Paul Leahy ◽  
Ana Deletic ◽  
David McCarthy
Keyword(s):  
Sediment Cores ◽  
Sediment Quality ◽  
Aquatic Systems ◽  
Quality Data ◽  
Aquatic Environments ◽  
Site Specific ◽  
European Settlement ◽  
Quality Guidelines ◽  
Water And Sediment ◽  
Water And Sediment Quality

When assigning site-specific restoration targets for deteriorating aquatic systems, it is necessary to have an understanding of the undisturbed or background state of the system. However, the site-specific characteristics of aquatic systems prior to disturbance are mostly unknown, due to the lack of historical water and sediment quality data. This study aims to introduce a method for filling this gap in our understanding, using dated sediment cores from the beds of aquatic environments. We used Bolin Billabong, a floodplain lake of the Yarra River (South-East Australia), as a case study to demonstrate the application of this method. We identified the concentrations of aluminium, cadmium, chromium, copper, iron, lead, manganese, nickel, tin and zinc at 8 cm intervals through the sediment core. This showed that aluminium, chromium, copper, iron, lead, nickel, tin and zinc concentrations in Bolin Billabong sediments significantly increased after European settlement in the river catchment in the mid-19th century. The differences between current Australian sediment quality guidelines trigger values and the background metal concentrations in Bolin Billabong sediments underscore the value of using locally relevant background toxicant concentrations when setting water and sediment quality targets.

scholarly journals Geometry-Wave Potential Quantified and Unified Properties in General Chemistry

2020 ◽  
Author(s):  
Zheng Tian
Keyword(s):  
General Chemistry ◽  
Surface Chemistry ◽  
Lewis Acid ◽  
Self Assembly ◽  
Redox Chemistry ◽  
Acid Base ◽  
Wave Potential ◽  
First Time

Many long-known but never-quantified properties in chapters of general chemistry have for the first time been quantitatively compared and consistently unified, using the newly introduced geometro-wave (GW) potential of particles (i.e. atoms, molecules, clusters, ions, and nanoparticles). Th GW Potential has helped update the electrochemistry, Lewis acid-base chemistry, redox chemistry, self-assembly, surface chemistry, catalysis, and inter-nanoparticle bonding.

scholarly journals Biochemical characterization of the purple form of Marinobacter hydrocarbonoclasticus nitrous oxide reductase

2012 ◽  
Vol 367 (1593) ◽  
pp. 1204-1212 ◽  
Author(s):  
Simone Dell'Acqua ◽  
Sofia R. Pauleta ◽  
José J. G. Moura ◽  
Isabel Moura
Keyword(s):  
Nitrous Oxide ◽  
Redox State ◽  
Biochemical Characterization ◽  
Specific Activity ◽  
Active Species ◽  
Nitrous Oxide Reductase ◽  
Strictly Anaerobic ◽  
Prolonged Incubation ◽  
Redox Active ◽  
Marinobacter Hydrocarbonoclasticus

Nitrous oxide reductase (N 2 OR) catalyses the final step of the denitrification pathway—the reduction of nitrous oxide to nitrogen. The catalytic centre (CuZ) is a unique tetranuclear copper centre bridged by inorganic sulphur in a tetrahedron arrangement that can have different oxidation states. Previously, Marinobacter hydrocarbonoclasticus N 2 OR was isolated with the CuZ centre as CuZ*, in the [1Cu 2+ : 3Cu + ] redox state, which is redox inert and requires prolonged incubation under reductive conditions to be activated. In this work, we report, for the first time, the isolation of N 2 OR from M. hydrocarbonoclasticus in the ‘purple’ form, in which the CuZ centre is in the oxidized [2Cu 2+ : 2Cu + ] redox state and is redox active. This form of the enzyme was isolated in the presence of oxygen from a microaerobic culture in the presence of nitrate and also from a strictly anaerobic culture. The purple form of the enzyme was biochemically characterized and was shown to be a redox active species, although it is still catalytically non-competent, as its specific activity is lower than that of the activated fully reduced enzyme and comparable with that of the enzyme with the CuZ centre in either the [1Cu 2+ : 3Cu + ] redox state or in the redox inactive CuZ* state.

Shape Forming of Alumina-Silica of High Thermal Stability for Space Propulsion Applications

2006 ◽  
Vol 45 ◽  
pp. 427-435 ◽  
Author(s):  
Daniel Amariei ◽  
Sylvie Rossignol ◽  
Charles Kappenstein
Keyword(s):  
Thermal Stability ◽  
Active Phase ◽  
Industrial Applications ◽  
High Thermal Stability ◽  
Bet Surface Area ◽  
Formulation Development ◽  
Space Propulsion ◽  
Catalytic Activities ◽  
Hydroxylammonium Nitrate ◽  
Si Doped

The replacement of toxic hydrazine used for catalytic propulsion by less toxic propellants such as ionic liquids is of hot interest. The challenge for this replacement is the formulation, development and shape forming of new catalysts. Efficient catalysts for the decomposition of aqueous 79 wt.-% HAN solutions (hydroxylammonium nitrate NH3OH+NO3 -) contain 10 wt.-% Pt active phase deposited on a support. Laboratory-made powder catalysts contain platinum supported on Si-doped alumina and display a good activity at low temperature. But, for industrial applications in propulsion thrusters, the pressure drop due to a powder is too high and consequently shape formed supports and catalysts must be prepared and investigated. Two catalyst types have been prepared (i) from shaped supports obtained at the laboratory level using the “oil-drop” method and (ii) from supports formed through an industrial procedure. Both shape formed samples display comparable properties as the powder support, such as high thermal stability linked to the presence q and d aluminas and similar BET surface area. Catalysts based on these supports show efficient catalytic activities.

An efficient method for collecting large samples of live copepods free from detritus

2010 ◽  
Vol 61 (5) ◽  
pp. 621 ◽  
Author(s):  
Carl J. Svensson ◽  
Glenn A. Hyndes ◽  
Paul S. Lavery
Keyword(s):  
Fatty Acids ◽  
Food Web ◽  
Trophic Levels ◽  
Aquatic Systems ◽  
New Method ◽  
Aquatic Environments ◽  
Web Studies ◽  
Large Samples ◽  
Large Numbers ◽  
Harpacticoid Copepods

Meiofauna are often important in the transfer of organic material to higher trophic levels in aquatic environments. However, in food web analysis the group is frequently pooled or ignored owing to the difficulty in isolating individual components of the assemblage. In this study, we developed and tested a new method for extracting photopositive and detritus-free copepod samples from sediments, and compared this method to a previous technique (Couch 1989). In our initial trials, ∼400 copepods (all orders included) were collected in 15 min compared with 60 copepods using Couch’s method. In subsequent trials that focussed on specific orders of copepods, our method was at least 10 times more efficient than Couch’s method at collecting cyclopoid and harpacticoid copepods from sediments. The new method requires very little supervision and there is no requirement for a particular intensity of light. This method can increase the collection of large numbers of photopositive copepods in aquatic systems, and thereby facilitate the inclusion of this important component into future food web studies, particularly those using biomarkers such as stable isotopes or fatty acids.

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