Photooxidation at Platinum Colloidal TiO2 Aqueous-Solution Interfaces. I. Ethylenediaminetetraacetic Acid and Related-Compounds

1986 ◽  
Vol 39 (5) ◽  
pp. 757 ◽  
Author(s):  
DN Furlong ◽  
D Wells ◽  
WHF Sasse
Keyword(s):  
Carbon Dioxide ◽  
Aqueous Solution ◽  
Ethylenediaminetetraacetic Acid ◽  
Oxidation Potential ◽  
Illumination Time ◽  
Carbonium Ions ◽  
Production Of Hydrogen ◽  
Glycine Derivatives ◽  
Lactic Acids ◽  
Exhaustive Oxidation

The photooxidation of ethylenediaminetetraacetic acid ( edta ) and related glycine derivatives, at Pt/TiO2/aqueous solution interfaces, has been monitored via the production of hydrogen and carbon dioxide. Yields are consistent with the exhaustive oxidation of methoxycarbonyl groups and the rate varied with the number and distribution of such groups. A photooxidation pathway is proposed which involves the oxidation of intermediate carbonium ions. Plausible molecular intermediates, such as formic acid and formaldehyde in the case of edta , have been shown in separate experiments to be photooxidized according to the proposed pathway. The maximum rate of oxidation for each donor depends on its oxidation potential and its tendency to adsorb on TiO2 surfaces. Desorption due to pH increase, as well as consumption of the donor, causes the rate to decline rapidly with illumination time. Acetic and malonic acids gave some hydrogen but underwent mainly (> c. 80%) photo-Kolbe decarboxylation to yield carbon dioxide and methane. By contrast the oxidation of oxomalonic, pyruvic and lactic acids proceeded mainly via a H2 producing pathway similar to that established for edta. The oxidation of pyruvic and lactic acids ceased at a yield of one mole of CO2 per mole of acid.

Atom Condensed Fukui Function for Condensed Phases and Biological Systems and Its Application to Enzymatic Fixation of Carbon Dioxide

2019 ◽  
Author(s):  
Javier Oller ◽  
David A. Sáez ◽  
Esteban Vöhringer-Martinez
Keyword(s):  
Carbon Dioxide ◽  
Aqueous Solution ◽  
Molecular System ◽  
Chemical Reactivity ◽  
Nucleophilic Attack ◽  
Stable Conformation ◽  
Fukui Functions ◽  
Reactivity Descriptors ◽  
Dynamics Simulations ◽  
Fixation Of Carbon Dioxide

<div><div><div><p>Local reactivity descriptors such as atom condensed Fukui functions are promising computational tools to study chemical reactivity at specific sites within a molecule. Their applications have been mainly focused on isolated molecules in their most stable conformation without considering the effects of the surroundings. Here, we propose to combine QM/MM Born-Oppenheimer molecular dynamics simulations to obtain the microstates (configurations) of a molecular system using different representations of the molecular environment and calculate Boltzmann weighted atom condensed local reac- tivity descriptors based on conceptual DFT. Our approach takes the conformational fluctuations of the molecular system and the polarization of its electron density by the environment into account allowing us to analyze the effect of changes in the molecular environment on reactivity. In this contribution, we apply the method mentioned above to the catalytic fixation of carbon dioxide by crotonyl-CoA carboxylase/reductase and study if the enzyme alters the reactivity of its substrate compared to an aqueous solution. Our main result is that the protein en- vironment activates the substrate by the elimination of solute-solvent hydrogen bonds from aqueous solution in the two elementary steps of the reaction mechanism: the nucleophilic attack of a hydride anion from NADPH on the α, β unsaturated thioester and the electrophilic attack of carbon dioxide on the formed enolate species.</p></div></div></div>

Characterization of a Polymeric Membrane for the Separation of Hydrogen in a Mixture with CO2

2016 ◽  
Vol 9 (1) ◽  
pp. 126-136 ◽  
Author(s):  
Dionisio H. Malagón-Romero ◽  
Alexander Ladino ◽  
Nataly Ortiz ◽  
Liliana P. Green
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Production ◽  
Test Performance ◽  
Low Cost ◽  
Time Lag ◽  
Polymeric Membrane ◽  
Biological Processes ◽  
Scanning Calorimetry ◽  
Environmentally Sustainable ◽  
Production Of Hydrogen

Hydrogen is expected to play an important role as a clean, reliable and renewable energy source. A key challenge is the production of hydrogen in an economically and environmentally sustainable way on an industrial scale. One promising method of hydrogen production is via biological processes using agricultural resources, where the hydrogen is found to be mixed with other gases, such as carbon dioxide. Thus, to separate hydrogen from the mixture, it is challenging to implement and evaluate a simple, low cost, reliable and efficient separation process. So, the aim of this work was to develop a polymeric membrane for hydrogen separation. The developed membranes were made of polysulfone via phase inversion by a controlled evaporation method with 5 wt % and 10 wt % of polysulfone resulting in thicknesses of 132 and 239 micrometers, respectively. Membrane characterization was performed using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), atomic force microscopy (AFM), and ASTM D882 tensile test. Performance was characterized using a 23 factorial experiment using the time lag method, comparing the results with those from gas chromatography (GC). As a result, developed membranes exhibited dense microstructures, low values of RMS roughness, and glass transition temperatures of approximately 191.75 °C and 190.43 °C for the 5 wt % and 10 wt % membranes, respectively. Performance results for the given membranes showed a hydrogen selectivity of 8.20 for an evaluated gas mixture 54% hydrogen and 46% carbon dioxide. According to selectivity achieved, H2 separation from carbon dioxide is feasible with possibilities of scalability. These results are important for consolidating hydrogen production from biological processes.

Controlled preparation of micro–nano hierarchical hollow calcium carbonate microspheres by pressurized-CO2 carbonization and their CaCO3:Eu3+ photoluminescence properties

CrystEngComm ◽  
2021 ◽  
Vol 23 (16) ◽  
pp. 3033-3042
Author(s):  
Liubin Shi ◽  
Mingde Tang ◽  
Yaseen Muhammad ◽  
Yong Tang ◽  
Lulu He ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Calcium Carbonate ◽  
Calcium Hydroxide ◽  
Hierarchical Structure ◽  
Ethylenediaminetetraacetic Acid ◽  
Disodium Salt ◽  
Hollow Microspheres ◽  
Photoluminescence Properties ◽  
Controlled Preparation

Herein, calcium carbonate hollow microspheres with a micro–nano hierarchical structure were successfully synthesized using disodium salt of ethylenediaminetetraacetic acid (EDTA-2Na) as an additive, by bubbling pressurized carbon dioxide and calcium hydroxide at 120 °C.

Chemical Absorption of Carbon Dioxide into Aqueous Solution of Potassium Threonate

2010 ◽  
Vol 45 (4) ◽  
pp. 497-507 ◽  
Author(s):  
Kyu-Suk Hwang ◽  
Dae-Won Park ◽  
Kwang-Joong Oh ◽  
Seong-Soo Kim ◽  
Sang-Wook Park
Keyword(s):  
Carbon Dioxide ◽  
Aqueous Solution ◽  
Chemical Absorption

Carbon dioxide absorption in aqueous solution of potassium glycinate + 2-amino-2-methyl-1-propanol as new absorbents

RSC Advances ◽  
2016 ◽  
Vol 6 (67) ◽  
pp. 62612-62623 ◽  
Author(s):  
Mohammad Ehsan Hamzehie ◽  
Hesam Najibi
Keyword(s):  
Carbon Dioxide ◽  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Carbon Dioxide Absorption

Aqueous solutions of potassium glycinate and mixtures with 2-amino-2-methyl-1-propanol (AMP) are investigated as new absorbents for carbon dioxide absorption.

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