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Maier, A. C., Herceglija Iglebaek, E. & Jonsson, M. (2019). Confirming the formation of hydroxyl radicals in the catalytic decomposition of H2O2 on metal oxides using coumarin as a probe. ChemCatChem, 11(22), 5435-5438
Open this publication in new window or tab >>Confirming the formation of hydroxyl radicals in the catalytic decomposition of H2O2 on metal oxides using coumarin as a probe
2019 (English)In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 11, no 22, p. 5435-5438Article in journal (Refereed) Published
Abstract [en]

Hydrogen peroxide can be catalytically decomposed to O2 and H2O on metal oxide surfaces in contact with aqueous solutions containing H2O2. The initial step in this process has been proposed to be the formation of surface‐bound hydroxyl radicals which has recently been verified using tris as a radical scavenger. Here, we make use of the unique fluorescent product 7‐hydroxycoumarin formed in the reaction between hydroxyl radicals and coumarin to probe the formation of surface‐bound hydroxyl radicals. The experiments clearly show that 7‐hydroxycoumarin is formed upon catalytic decomposition of H2O2 in aqueous suspensions containing ZrO2‐particles and coumarin, thereby confirming the formation of surface‐bound hydroxyl radicals in this process. The results are quantitatively compared to results on the same system using tris as a probe for hydroxyl radicals. The effects of the two probes on the system under study are compared and it is concluded that coumarin has a significantly lower impact on the system.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2019
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-261217 (URN)10.1002/cctc.201901316 (DOI)000497857800007 ()2-s2.0-85074344246 (Scopus ID)
Note

QC 20191212

Available from: 2019-10-03 Created: 2019-10-03 Last updated: 2019-12-12Bibliographically approved
Leandri, V., Gardner, J. M. & Jonsson, M. (2019). Coumarin as a Quantitative Probe for Hydroxyl Radical Formation in Heterogeneous Photocatalysis. The Journal of Physical Chemistry C, 123(11), 6667-6674
Open this publication in new window or tab >>Coumarin as a Quantitative Probe for Hydroxyl Radical Formation in Heterogeneous Photocatalysis
2019 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, no 11, p. 6667-6674Article in journal (Refereed) Published
Abstract [en]

In this work, we have assessed coumarin as a quantitative probe for hydroxyl radical formation in heterogeneous photocatalysis. Upon reaction with the hydroxyl radical, coumarin produces several hydroxylated products, of which one, 7-OH-coumarin, is strongly fluorescent. The fluorescence emission is strongly affected by inner filtering due to the presence of coumarin. Therefore, we performed a series of calibration experiments to correct for the coumarin concentration. From the calibration experiments, we could verify that the inner-filtering effect can be attributed to the competing absorption of the fluorescence excitation light between coumarin and 7-OH-coumarin. Through judicious calibration for the inner-filtering effects, the corrected results for the photocatalytic system show that the rate of hydroxyl scavenging is constant with time for initial coumarin concentrations of ≥50 μM under the conditions of our experiments. The rate increases linearly with coumarin concentration, as expected from the Langmuir–Hinshelwood model. Within the coumarin concentration range used here, the photocatalyst surface does not become saturated. Given the fact that the highest coumarin concentration used (1 mM) in this work is quite close to the solubility limit, we conclude that coumarin cannot be used to assess the full photocatalytic capacity of the system, i.e., surface saturation is never reached. The rate of hydroxyl radical scavenging will, to a large extent, depend on the affinity to the surface, and it is therefore not advisable to use coumarin as a probe for photocatalytic efficiency when comparing different photocatalysts.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-249493 (URN)10.1021/acs.jpcc.9b00337 (DOI)000462260700040 ()2-s2.0-85062883293 (Scopus ID)
Note

QC 20190426

Available from: 2019-04-12 Created: 2019-04-12 Last updated: 2019-04-26Bibliographically approved
Toijer, E. & Jonsson, M. (2019). H 2 O 2 and γ-radiation induced corrosion of 304L stainless steel in aqueous systems. Radiation Physics and Chemistry, 159, 159-165
Open this publication in new window or tab >>H 2 O 2 and γ-radiation induced corrosion of 304L stainless steel in aqueous systems
2019 (English)In: Radiation Physics and Chemistry, ISSN 0969-806X, E-ISSN 1879-0895, Vol. 159, p. 159-165Article in journal (Refereed) Published
Abstract [en]

In light-water reactors the water used as neutron moderator and coolant is subjected to a constant radiation field which leads to the formation of a number of oxidizing and reducing species. In this work, the reactivity of the radiolysis product H 2 O 2 towards the 304L alloy, commonly used for structural materials in nuclear power plants, was investigated as well as oxidative dissolution of steel components as a consequence of γ-radiation and chemically added H 2 O 2 . The concentration of hydrogen peroxide as a function of time was monitored in the presence of different amounts of steel powder, and the second order reaction rate constant was determined to k 2 = (1.8 ± 0.2) × 10 −10 m s −1 . In the case of catalytic decomposition of hydrogen peroxide, hydroxyl radicals are formed which can be scavenged by methanol. In this reaction formaldehyde is formed, which can be detected spectroscopically. A high yield of formaldehyde was observed, indicating that catalytic decomposition is the main reaction path of H 2 O 2 in the current system. A significant contribution of the homogeneous Fenton reaction to both the reaction rate constant and the formaldehyde formation must however be considered, as Fe(II) will be released from the oxide layer in solution. In the case of γ-irradiation, an increased nickel content in solution compared to background experiments is seen. When the steel is subjected to chemically added hydrogen peroxide on the other hand, the chromium content in solution is increased. This indicates that the different types of exposure will impact different parts of the oxide layer characterized by different composition. © 2019

Place, publisher, year, edition, pages
Elsevier Ltd, 2019
Keywords
Formaldehyde, Gamma rays, Hydrogen peroxide, Iron compounds, Light water reactors, Neutron irradiation, Nuclear fuels, Nuclear power plants, Oxidation, Peroxides, Radiation chemistry, Rate constants, Steel corrosion, 304L stainless steel, Catalytic decomposition, Gamma irradiation, Neutron moderators, Oxidative dissolution, Radiation-induced, Radiolysis products, Second-order reaction, Austenitic stainless steel, chromium, hydroxyl radical, methanol, nickel, stainless steel, Article, corrosion, decomposition, dissolution, Fenton reaction, radiolysis, surface area
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-252508 (URN)10.1016/j.radphyschem.2019.02.047 (DOI)000472690000022 ()2-s2.0-85062715868 (Scopus ID)
Note

QC 20190711

Available from: 2019-07-11 Created: 2019-07-11 Last updated: 2019-07-11Bibliographically approved
Kumagai, Y., Barreiro Fidalgo, A. & Jonsson, M. (2019). Impact of Stoichiometry on the Mechanism and Kinetics of Oxidative Dissolution of UO 2 Induced by H 2 O 2 and γ-Irradiation. The Journal of Physical Chemistry C, 123(15), 9919-9925
Open this publication in new window or tab >>Impact of Stoichiometry on the Mechanism and Kinetics of Oxidative Dissolution of UO 2 Induced by H 2 O 2 and γ-Irradiation
2019 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, no 15, p. 9919-9925Article in journal (Refereed) Published
Abstract [en]

Radiation-induced oxidative dissolution of uranium dioxide (UO 2 ) is one of the most important chemical processes of U driven by redox reactions. We have examined the effect of UO 2 stoichiometry on the oxidative dissolution of UO 2 in aqueous sodium bicarbonate solution induced by hydrogen peroxide (H 2 O 2 ) and γ-ray irradiation. By comparing the reaction kinetics of H 2 O 2 between stoichiometric UO 2.0 and hyper-stoichiometric UO 2.3 , we observed a significant difference in reaction speed and U dissolution kinetics. The stoichiometric UO 2.0 reacted with H 2 O 2 much faster than the hyper-stoichiometric UO 2.3 . The U dissolution from UO 2.0 was initially much lower than that from UO 2.3 but gradually increased as the oxidation by H 2 O 2 proceeded. Increase in the initial H 2 O 2 concentration caused decrease in the U dissolution yield with respect to the H 2 O 2 consumption both for UO 2.0 and UO 2.3 . This decrease in the U dissolution yield is attributed to the catalytic decomposition of H 2 O 2 on the surface of UO 2 . The γ-ray irradiation induced the U dissolution that is analogous to the kinetics by the exposure to a low concentration (2 × 10 -4 mol dm -3 ) of H 2 O 2 . The exposure to higher H 2 O 2 concentrations caused lower U dissolution and resulted in deviation from the U dissolution behavior by γ-ray irradiation.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
Keywords
Dissolution, Irradiation, Kinetics, Reaction kinetics, Redox reactions, Sodium bicarbonate, Stoichiometry, Uranium dioxide, Bicarbonate solution, Catalytic decomposition, Dissolution behavior, Dissolution kinetics, Gamma-ray irradiation, Low concentrations, Mechanism and kinetics, Oxidative dissolution, Gamma rays
National Category
Other Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-255911 (URN)10.1021/acs.jpcc.9b00862 (DOI)000465488600032 ()2-s2.0-85064646707 (Scopus ID)
Note

QC 20190822

Available from: 2019-08-22 Created: 2019-08-22 Last updated: 2019-10-24Bibliographically approved
Chen, S., Abdel-Magied, A. F., Fu, L., Jonsson, M. & Forsberg, K. (2019). Incorporation of strontium and europium in crystals of α-calcium isosaccharinate. Journal of Hazardous Materials, 364, 309-316
Open this publication in new window or tab >>Incorporation of strontium and europium in crystals of α-calcium isosaccharinate
Show others...
2019 (English)In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 364, p. 309-316Article in journal (Refereed) Published
Abstract [en]

The final repository for short-lived, low and intermediate level radioactive waste in Sweden is built to act as a passive repository. Already within a few years after closure water will penetrate the repository and conditions of high alkalinity (pH 10.5―13.5) and low temperature (< 7 °C) will prevail. The mobility of radionuclides in the repository is dependent on the radionuclides distribution between solid and liquid phases. In the present work the incorporation of strontium (II) and europium (III) in α-calcium isosaccharinate (ISA) under alkaline conditions (pH ~10) at 5 °C and 50 °C have been studied. The results show that strontium and europium are incorporated into α-Ca(ISA)2 when crystallized both at 5 °C and 50 °C. Europium is incorporated to a greater extent than strontium. The highest incorporation of europium and strontium at 5 °C rendered the phase compositions Ca0.986Eu0.014(ISA)2 (2.4% of Eu(ISA)3 by mass) and Ca0.98Sr0.02(ISA)2 (2.2% of Sr(ISA)2 by mass). XPS spectra show that both trivalent and divalent Eu coexist in the Eu incorporated samples. Strontium ions were found to retard the elongated growth of the Ca(ISA)2crystals. The incorporation of Sr2+ and Eu3+ into the solid phase of Ca(ISA)2 is expected to contribute to a decreased mobility of these ions in the repository.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Mobility, radionuclides, isosaccharinate, precipitation
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-235920 (URN)10.1016/j.jhazmat.2018.10.001 (DOI)000452926500034 ()30384240 (PubMedID)2-s2.0-85055549831 (Scopus ID)
Funder
Swedish Radiation Safety Authority, SSM2016-2126
Note

QC 20181010

Available from: 2018-10-08 Created: 2018-10-08 Last updated: 2019-11-11Bibliographically approved
Dahlgren, B., Dispenza, C. & Jonsson, M. (2019). Numerical Simulation of the Kinetics of Radical Decay in Single-Pulse High-Energy Electron-Irradiated Polymer Aqueous Solutions. Journal of Physical Chemistry A, 123(24), 5043-5050
Open this publication in new window or tab >>Numerical Simulation of the Kinetics of Radical Decay in Single-Pulse High-Energy Electron-Irradiated Polymer Aqueous Solutions
2019 (English)In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 123, no 24, p. 5043-5050Article in journal (Refereed) Published
Abstract [en]

A new method for the numerical simulation of the radiation chemistry of aqueous polymer solutions is introduced. The method makes use of a deterministic approach combining the conventional homogeneous radiation chemistry of water with the chemistry of polymer radicals and other macromolecular species. The method is applied on single-pulse irradiations of aqueous polymer solutions. The speciation of macromolecular species accounts for the variations in the number of alkyl radicals per chain, molecular weight, and number of internal loops (as a consequence of an intramolecular radical-radical combination). In the simulations, the initial polymer molecular weight, polymer concentration, and dose per pulse (function of pulse length and dose rate during the pulse) were systematically varied. In total, 54 different conditions were simulated. The results are well in line with the available experimental data for similar systems. At a low polymer concentration and a high dose per pulse, the kinetics of radical decay is quite complex for the competition between intra- and intermolecular radical-radical reactions, whereas at a low dose per pulse the kinetics is purely second-order. The simulations demonstrate the limitations of the polymer in scavenging all the radicals generated by water radiolysis when irradiated at a low polymer concentration and a high dose per pulse. They also show that the radical decay of lower-molecular-weight chains is faster and to a larger extent dominated by intermolecular radical-radical reactions, thus explaining the mechanism behind the experimentally observed narrowing of molecular weight distributions.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-255441 (URN)10.1021/acs.jpca.9b03013 (DOI)000472800600005 ()31140810 (PubMedID)2-s2.0-85067854545 (Scopus ID)
Note

QC 20190812

Available from: 2019-08-12 Created: 2019-08-12 Last updated: 2019-10-15Bibliographically approved
Dahlgren, B., Sabatino, M. A., Dispenza, C. & Jonsson, M. (2019). Numerical Simulations of Nanogel Synthesis Using Pulsed Electron Beam. Macromolecular Theory and Simulations, Article ID 1900046.
Open this publication in new window or tab >>Numerical Simulations of Nanogel Synthesis Using Pulsed Electron Beam
2019 (English)In: Macromolecular Theory and Simulations, ISSN 1022-1344, E-ISSN 1521-3919, article id 1900046Article in journal (Refereed) Published
Abstract [en]

In this work, a new method for numerical simulation of the radiation chemistry of aqueous polymer solutions exposed to a sequence of electron pulses is presented. The numerical simulations are based on a deterministic approach encompassing the conventional homogeneous radiation chemistry of water as well as the chemistry of polymer radicals. The multitude of possible reactions in the macromolecular system is handled by allowing for a large number of macromolecular species. The speciation of macromolecular species is done to account for variations in molecular weight, number of alkyl radicals per chain, number of peroxyl radicals per chain, number of oxyl radicals per chain, and number of internal loops. As benchmarking, previously published results from a series of experiments on pulsed irradiation of aqueous poly(N-vinylpyrrolidone) (PVP) solutions are used. The numerical simulations clearly show that the pulsed nature of the radiation must be accounted for. The simulations qualitatively reproduce the experimentally observed impact of initial gas saturation (air and N2O) and polymer concentration on the molecular chain length upon irradiation. The formation of double bonds as a function of dose as well as the impact of effective dose rate on the final chain length are also qualitatively reproduced in the simulations.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2019
Keywords
kinetics, macroradicals, nanogels, radiation, simulations
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-263335 (URN)10.1002/mats.201900046 (DOI)000491100000001 ()2-s2.0-85074321423 (Scopus ID)
Note

QC 20191206

Available from: 2019-12-06 Created: 2019-12-06 Last updated: 2019-12-06Bibliographically approved
Maier, A. C. & Jonsson, M. (2019). Pd‐Catalyzed Surface Reactions of Importance in Radiation Induced Dissolution of Spent Nuclear Fuel Involving H2. ChemCatChem
Open this publication in new window or tab >>Pd‐Catalyzed Surface Reactions of Importance in Radiation Induced Dissolution of Spent Nuclear Fuel Involving H2
2019 (English)In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899Article in journal (Refereed) Published
Abstract [en]

To assess the influence of metallic inclusions (ϵ‐particles) on the dissolution of spent nuclear fuel under deep repository conditions, Pd‐catalyzed reactions of H2O2, O2 and UO22+ with H2 were studied using Pd‐powder suspensions. U(VI) can efficiently be reduced to less soluble U(IV) on Pd‐particles in the presence of H2. The kinetics of the reaction was found to depend on the H2 partial pressure at pH2≤5.1×10−2 bar. In comparison, the H2 pressure dependence for the reduction of H2O2 on Pd also becomes evident below 5.1×10−2 bar. Surface bound hydroxyl radicals are formed as intermediate species produced during the catalytic decomposition of H2O2 on oxide surfaces. While a significant amount of surface bound hydroxyl radicals were scavenged during the catalytic decomposition of H2O2 on ZrO2, no scavenging was observed in the same reaction on Pd. This indicates a different reaction mechanism for H2O2 decomposition on Pd compared to metal oxides and is in contrast to current literature. While Pd is an excellent catalyst for the synthesis of H2O2 from H2 and O2, a similar catalytic activity that was previously proposed for ZrO2 could not be confirmed.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-261213 (URN)10.1002/cctc.201901128 (DOI)000494251600016 ()2-s2.0-85073687840 (Scopus ID)
Note

QC 20191004

Available from: 2019-10-03 Created: 2019-10-03 Last updated: 2019-12-04Bibliographically approved
Barreiro Fidalgo, A. & Jonsson, M. (2019). Radiation induced dissolution of (U, Gd)O-2 pellets in aqueous solution - A comparison to standard UO2 pellets. Journal of Nuclear Materials, 514, 216-223
Open this publication in new window or tab >>Radiation induced dissolution of (U, Gd)O-2 pellets in aqueous solution - A comparison to standard UO2 pellets
2019 (English)In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 514, p. 216-223Article in journal (Refereed) Published
Abstract [en]

The behavior of spent nuclear fuel exposed to groundwater is crucial in the safety assessment of a deep geological repository for spent nuclear fuel. For this reason, leaching experiments on spent nuclear fuel as well as non-radioactive analogues have been conducted for several decades. Although the processes involved can be considered to be fairly well understood, there is a need for further experimental studies whenever new fuel types are introduced. Fuels with burnable absorbers are now in use but very little is known about their behavior under repository conditions. In this work, the impact of burnable absorbers doping (Gd, 3-8%wt.) on the oxidative dissolution of UO2 in an aqueous system was studied in H2O2 and gamma-irradiation induced dissolution experiments. The results showed a significant decrease in uranium dissolution and lower reactivity towards H2O2 for (U,Gd)O-2 pellets compared to standard UO2. The resulting decrease in the final oxidative dissolution yield was mainly attributed to decreased redox reactivity of the UO2-matrix upon doping. The results of the gamma radiation exposures display an even larger effect of Gd-doping. These findings indicate that other processes are involved in the radiation-induced dissolution of Gd-doped UO2 compared to pure UO2. 

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2019
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-241303 (URN)10.1016/j.jnucmat.2018.11.037 (DOI)000454829000025 ()2-s2.0-85057718007 (Scopus ID)
Note

QC 20190125

Available from: 2019-01-25 Created: 2019-01-25 Last updated: 2019-04-09Bibliographically approved
Leandri, V., Gardner, J. M. & Jonsson, M. (2019). Reply to "Comment on 'Coumarin as a Quantitative Probe for Hydroxyl Radical Formation in Heterogeneous Photocatalysis'". The Journal of Physical Chemistry C, 123(33), 20685-20686
Open this publication in new window or tab >>Reply to "Comment on 'Coumarin as a Quantitative Probe for Hydroxyl Radical Formation in Heterogeneous Photocatalysis'"
2019 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, no 33, p. 20685-20686Article in journal, Editorial material (Other academic) Published
Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-259445 (URN)10.1021/acs.jpcc.9b06021 (DOI)000482545700067 ()2-s2.0-85071659297 (Scopus ID)
Note

QC 20190923

Available from: 2019-09-23 Created: 2019-09-23 Last updated: 2019-09-23Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-0663-0751

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