The Effect of Hydrogen Peroxide Concentration on the Oxidative Dissolution of Unirradiated Uranium Dioxide

2000 ◽  
Vol 663 ◽  
Author(s):  
J. De Pablo ◽  
I. Casas ◽  
F. Clarens ◽  
F. El Aamrani ◽  
M. Rovira
Keyword(s):  
Hydrogen Peroxide ◽  
Dissolution Rate ◽  
Solid Surface ◽  
Uranium Dioxide ◽  
Consumption Rate ◽  
Reaction Order ◽  
Chemical Processes ◽  
Surface Chemical ◽  
Batch Experiments ◽  
Oxidative Dissolution

ABSTRACTThe dissolution rate of unirradiated uranium dioxide was studied in batch experiments as a function of hydrogen peroxide concentration (from 10−5 to 10−3 mol dm−3). Unirradiated UO2(s) was used in order to differentiate surface chemical processes from radiolytic effects. Dissolution rates were determined from both uranium release and hydrogen peroxide consumption. Results showed that H2O2consumption rate was higher than UO2 dissolution rate. This observation may indicate that the overall UO2 oxidative dissolution process would be controlled by the dissolution of the oxidized solid surface. The calculated hydrogen peroxide reaction order was 1 in the H2O2 concentration range from 10−5 to 10−4 mol dm−3, while at higher concentrations no clear dependence was observed.

Photocatalytic Treatment of Wastewater From 5–Fluorouracil Manufacturing

1996 ◽  
Vol 118 (1) ◽  
pp. 2-8 ◽  
Author(s):  
M. Anheden ◽  
D. Y. Goswami ◽  
G. Svedberg
Keyword(s):  
Hydrogen Peroxide ◽  
Photocatalytic Oxidation ◽  
Uv Light ◽  
Substantial Reduction ◽  
Reduction Rate ◽  
Reaction Rates ◽  
Batch Experiments ◽  
Cod Reduction ◽  
Potential Use ◽  
Percent Decrease

This paper presents some of the experimental results from a study conducted to demonstrate the potential use of photocatalytic oxidation for decolorization and COD reduction of wastewater from 5–fluorouracil manufacturing. A series of batch experiments, were carried out using diluted solutions of the wastewater with 0.1 percent w/v TiO2. Low pressure mercury lamps were used to simulate the UV part of sunlight. The experiments showed that a complete decolorization and a substantial reduction of COD was achieved within 20 hours with a 20 percent solution. During the reaction period, the pH was noted to decrease considerably, indicating formation of acids. Adding hydrogen peroxide to the solution was found to significantly increase the reaction rates. Adding 2400 ppm of H2O2 gave an 80 percent decrease in color in one hour and a 70-80 percent decrease in COD in 20 hours. The influence of UV-light intensity was also examined. This experiment showed that with a UV-intensity of 15 W/m2, i.e., a cloudy day, the decolorization rate was still considerable, while the COD reduction rate was very low.

Significance of acetogenic H2 consumption in dark fermentation and effectiveness of pH

2008 ◽  
Vol 57 (6) ◽  
pp. 809-814 ◽  
Author(s):  
B. Calli ◽  
J. Zhao ◽  
E. Nijssen ◽  
K. Vanbroekhoven
Keyword(s):  
Partial Pressure ◽  
Consumption Rate ◽  
H2 Production ◽  
Dark Fermentation ◽  
Batch Experiments ◽  
Acetate Production ◽  
Butyrate Fermentation ◽  
Reduction Of Co2 ◽  
H2 Yield

Two identical thermophilic H2 fermenters (R1 and R2) were operated at different pH levels between 4.7 and 5.7. In R1, several unexpected and severe drops in H2 yield inversely proportional to increase in acetate production were experienced at pH 5.5 and 5.7. In contrast, R2 operated at pH 5and 4.7 performed more stable H2 production mainly through butyrate fermentation. Although the H2 partial pressure (>50 kPa) was far above the favorable values, acetate was produced as well as butyrate in all pH levels tested. To determine whether some portion of the acetate is produced through another pathway such as autotrophic synthesis via H2 dependent reduction of CO2 or not, batch dissolved H2 consumption rate tests were performed at pH 5.0, 5.5 and 6. The specific H2 consumption rate was 488(±49) μmol/gVSS.hr at pH 6 and slightly higher than at pH 5and 5.5. The results of continuous and batch experiments revealed that acetogenic H2 consumption is more favorable at pH levels above 5.5 and is one of the reasons of instabilities in dark fermentative H2 production.

AN EMPIRICAL STUDY ON THE HYDROGEN PEROXIDE REACTION WITH IODIDE IN ACID CONDITION

2015 ◽  
Vol 11 (1) ◽  
pp. 72
Author(s):  
Ayuni Dita Rosalia ◽  
Patiha Patiha ◽  
Eddy Heraldy
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction Order ◽  
Ph Value ◽  
Order Reaction ◽  
Isolation Method ◽  
Acid Condition ◽  
Rate Law ◽  
Mechanism Of Reaction ◽  
Oxygen Gas

<p>This research aimed to find out I<sup>-</sup> reaction order in the mechanism of  hydrogen peroxide reaction with iodide in acid condition, to find out the form of rate law, and to show the role of H<sup>+</sup> in reaction. The experiment for determining reaction order was carried out with isolation method using UV-Vis spectrophotometry. The order reaction was obtained from the <em>r</em> value approaching one, the results of its linear regression. The form of rate law was viewed from the presence or absence of oxygen gas. Meanwhile the role of H<sup>+</sup> in reaction was determined by observing the pH value in 60 minutes.</p><p>The result of experiment shows that the mechanism of reaction has rate law in the form of fraction, in which I<sup>-</sup> could be in zero and first orders. In addition, the rate law in this experimental condition is not an addition in the absence of O<sub>2</sub> and relatively equal <em>k</em><sub>obs</sub> value in the same order. The role of H<sup>+ </sup>is observed not as catalyst, but reactant.</p>

Feasibility Study of Raman Spectroscopy as a Tool to Investigate the Liquid-Phase Chemistry of Aliphatic Organic Peroxides

1997 ◽  
Vol 51 (1) ◽  
pp. 74-80 ◽  
Author(s):  
Peter Jacob ◽  
Bernhard Wehling ◽  
Wieland Hill ◽  
Dieter Klockow
Keyword(s):  
Hydrogen Peroxide ◽  
Raman Spectroscopy ◽  
Liquid Phase ◽  
Chemical Processes ◽  
Organic Peroxides ◽  
Time Resolved ◽  
In Situ Investigation ◽  
Phase Chemistry ◽  
Kinetics Of

The described investigations are focused on peroxides occurring as products in atmospheric chemical processes, namely, hydrogen peroxide, methylhydroperoxide, hydroxymethylhydroperoxide, bis-(hydroxymethyl)peroxide, 1-hydroxyethylhydroperoxide, bis-(hydroxyethyl)peroxide, and hydroxymethylmethylperoxide. The compounds are identified and determined through the position and intensity of their characteristic O–O stretching bands in the range between 767 and 878 cm−1. Time-resolved Raman spectroscopy of peroxide solutions permits the in situ investigation of pathways and kinetics of reactions between peroxides and aldehydes.

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