DOCSLIB.ORG

Photochemical Cycling of Iron Mediated by Dicarboxylates

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Photochemical Cycling of Iron Mediated by Dicarboxylates 中国科技论文在线 http://www.paper.edu.cn Environ. Sci. Technol. 2010, 44, 263–268 In general, the monomeric ferric complex FeIII(OH)2+ is Photochemical Cycling of Iron the most photoactive species in the absence of organic ligands in clouds and fog (3). The photolysis of FeIII(OH)2+ under UV Mediated by Dicarboxylates: Special • Effect of Malonate irradiation leads to generation of Fe(II) and OH(eq 1). + hv • FeIII(OH)2 98 Fe(II) + OH (1) ZHAOHUI WANG, XI CHEN, HONGWEI JI, WANHONG MA, CHUNCHENG CHEN, AND • DOM + OH f oxidized products (2) JINCAI ZHAO* Beijing National Laboratory for Molecular Sciences, Key Extensive field measurements have shown that dissolved Laboratory of Photochemistry, Institute of Chemistry, The organic matters (DOM) are very ubiquitous in atmospheric Chinese Academy of Sciences, Beijing 100190, China water droplets where the dissolved iron coexists at a comparable concentration (1). DOM that have relatively poor Received July 1, 2009. Revised manuscript received affinity to Fe(III), such as most monocarboxylates, may November 1, 2009. Accepted November 24, 2009. enhance the production of Fe(II) by scavenging •OH radical (eq 2), which decreases the rate of reoxidation of newly generated Fe(II) (9). Our recent work also revealed that influx of various DOM (10) or inorganic chromium species (11) can Photochemical redox cycling of iron coupled with oxidation change Fe(II)/Fe(total) ratio in different ways. of malonate (Mal) ligand has been investigated under conditions Among these Fe(III)-DOM species, Fe(III)-oxalato com- that are representative of atmospheric waters. Malonate plexes are highlighted for their considerably high photoac- exhibited significantly different characteristics from oxalate tivity under sunlight irradiation. The photolysis of ferrioxalate and other dicarboxylates (or monocarboxylates). Both strong complex may proceed as follows (eqs 3-8) (4, 5): chelating ability with Fe(III) and strong molar absorptivities, but hv III 3- 98 III -+ •- much low efficiency of Fe(II) formation (ΦFe(II) ) 0.0022 ( [Fe (C2O4)3] [Fe (C2O4)2] 2CO2 (3a) 0.0009, 300-366 nm) were observed for Fe(III)-Mal complexes (FMCs). Fe(III) speciation calculation indicated that Mal is hv III 3- 98 II 2- + •- capable of mediating the proportion between two photoactive [Fe (C2O4)3] [Fe (C2O4)2] C2O4 (3b) species of Fe(III)-OH complexes and FMCs by changing •- - - - the Mal concentration. Spin-trapping electron spin resonance CO + [FeIII(C O ) ]3 f [FeII(C O ) ]2 + CO + C O2 · 2 2 4 3 2 4 2 2 2 4 (ESR) experiments proved the formation of both the CH2COOH · (4) and OH radicals at lower total Mal concentration ([Mal]T), but · •- + f + •- only CH2COOH at higher concentrations of malonate, providing CO2 O2 CO2 O2 (5) strong evidence for competition between malonate and OH- and •- + + T • subsequent different photoreaction pathways. Once FMCs O2 H HO2 (6) • dominate the Fe(III) speciation, both photoproduction and 2HO f H O + O (7) photocatalyzed oxidation of Fe(II) will be greatly decelerated. 2 2 2 2 + f + • + - There exists an induction period for both formation and decay Fe(II) H2O2 Fe(III) OH OH (8) of Fe(II) until FeIII(OH)2+ species become the prevailing Fe(III) forms over FMCs as Mal ligand is depleted. A quenching Ferrioxalate complex absorbs a photon and undergoes mechanism of Mal in the Fe(II) photoproduction is proposed. photodissociation without electron transfer from the oxalate to iron (eq 3a) (12) or with a ligand-to-metal charge transfer The present study is meaningful to advance our understanding (LMCT) process, yielding Fe(II) and oxalate radical anion of iron cycling in acidified carbon-rich atmospheric waters. •- •- 0 (C2O4 ) (eq 3b) (5, 13). CO2 is a strong reducing agent (E )-1.8 V (NHE)) and can react with another ferrioxalate •- Introduction molecule or can instead reduce O2 to superoxide anion (O2 ) at near-diffusion-controlled rate (k ) 2.4 × 109 M-1 s-1)(14). Iron species have been identified as a ubiquitous component The photochemically generated Fe(II) can be reoxidized by •- • • in atmospheric water droplets (i.e., cloud, rain, or fog droplets) O2,O2 /HO2, OH, H2O2, and other oxidants. in field measurements (1). The maximum concentration of Malonic and succinic acids are also dominant dicarboxylic dissolved iron species was up to 200 µM in fogwater (2). acids only inferior to oxalic acid in carbon-rich atmospheric Photochemistry of atmospheric iron has a significant effect waters (7, 15). Since oxalate and malonate have the strongest on numerous chemical processes in atmospheric waters, chelating capacity with Fe(III) among all dicarboxylates and especially in redox and radical chain reactions such as natural monocarboxylates (see Table S1), the photochemistry of fluctuation of reactive oxygen species (ROS) (3-5), oxidation Fe-malonate complexes is expected to be important in iron of dissolved sulfur dioxide (SO2)(6) and organic substances cycling of atmospheric waters. However, there is little (7), and redox cycling of other trace metals (e.g., Cu, Mn) (8). information available so far regarding the photochemistry Furthermore, photolysis of iron species could contribute to of Fe(III)-dicarboxylate complexes except for that of ferri- iron input to open-ocean surface water via atmospheric oxalate (4). deposition, thereby increasing the bioavailability of iron to The objective of this study is to investigate the photo- aquatic biota (6). chemical behaviors of Fe(III)-malonate complexes (FMCs) comparing with those of Fe(III) complexes of oxalate and * Corresponding author fax: +86-10-8261-6495; e-mail: jczhao@ other carboxylates. The effect of malonate ligand on iron iccas.ac.cn. cycling and the photochemical reaction mechanism are also 10.1021/es901956x 2010 American Chemical Society VOL. 44, NO. 1, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 263 Published on Web 12/09/2009 转载 中国科技论文在线 http://www.paper.edu.cn discussed. One of the most important findings is that, in comparing with ferrioxalate/ferric hydroxo species, a high level of Fe(II)/Fe(t) can be maintained under UVA irradiation in the presence of excess Mal. This phenomenon is unique among the dicarboxylates (C2-C6) and monocarboxylates (C1-C3). Experimental Section Chemicals. Iron(III) perchlorate hydrate, iron(II) perchlorate hydrate, and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) were purchased from Aldrich. 5,5-Dimethyl-1-pyrroline-N- oxide (DMPO) was from Sigma Chemical Co. Iron (III) tripotassium oxalate trihydrate was from Alfa Aesar. Oxalic acid, malonic acid, sodium hydroxide, perchloric acid, and 1,10-phenanthroline were of reagent grade and used as supplied. Barnstead UltraPure water (18.3 MΩ cm) was used FIGURE 1. UV-vis absorption spectra for solutions containing for all experiments. 100 µM Fe(III) and Mal ligand with different concentrations. Experimental Procedures. A 100-W Hg lamp (Toshiba Inset: Speciation (molar fraction) of 100 µM Fe(III) in solutions SHL-100UVQ-2) was employed as the ultraviolet irradiation with total malonate concentration ([Mal]T) between 10 and 1000 source. It mainly emits at 312 and 366 nm (16), overlapping µM. pH, 3.0. the solar UVA spectrum (320-400 nm) (see Figure S1). All experiments were conducted in a 70-mL cylindrical Pyrex (20). Typical instrumental conditions were as follows: center vial (Corning, Inc.) under continuous magnetic stirring. The field, 3480 G; sweep width, 100 G; resolution, 1024 pts; Pyrex vial also served as a high-pass filter so that only light microwave frequency, ∼9.77 GHz; microwave power, 12.68 with wavelengths greater than 290 nm penetrated into the mW; modulation frequency, 100 kHz. To minimize experi- vessel. Unless otherwise specified, all experiments were mental errors, the same quartz capillary was used for all the performed under exposure to air at room temperature. An measurements. The simulations of ESR spectra were obtained exhaust fan was employed during all the reaction processes with the use of WinSim EPR simulation software. to maintain the temperature below 35 °C. Fe(III)-organic acid solutions were freshly prepared by dilution of stock Results and Discussion solutions of 0.01 M dicarboxylic acids (DAs), 5 mM Fe(III) at Fe(III) Speciation. Table S1 (see Supporting Information) pH 1.5 (HClO4). The initial pH was adjusted with dilute HClO4 summarizes Fe(III) complexes with different carboxylates or NaOH. Under our experimental conditions ([Fe(III)], 100 and the corresponding equilibrium constants. Malonate µM; pH 3.0), the polynuclear iron complexes are negligible shows strong complexation ability with Fe(III) and is capable and are not considered in the photochemistry of iron cycling of forming mono-, di-, and trimalonato complexes with (see discussion in Supporting Information). For deaerated Fe(III), although the equilibrium constant for each stoichi- experiments, the solutions in the cap-sealed Pyrex vial were ometry of Fe(III)-Mal species is somewhat lower than that bubbled with high-purity Ar (O2 e 0.001%) for at least 20 min of the corresponding Fe(III)-oxalate complex. Due to their prior to UV irradiation and continuously purged throughout poor complexation capacity with Fe(III) (21, 22), the well- the experiment. During each kinetic experiment, a 1-mL known photochemistry of Fe(III)-OH complex is predomi- aliquot was sampled with a new syringe each time and nant in the presence of other mono- or dicarboxylates. immediately disposed for the consequent analysis. Figure 1 shows the speciation of Fe(III) as a function of Methods and Analysis. The concentration of Fe(II) was total malonate concentration ([Mal]T) at pH 3.0. The con- measured spectrophotometrically by a modified phenan- centrations of all the hexaaquo and hydroxylated Fe(III) throline method (10, 17). Briefly, 0.5 mL of 1,10-phenan- complexes decreased significantly with increasing [Mal]T, throline solution (5.0 mM), 1 mL of sodium acetate/acetic whereas FMCs predominated the speciation of Fe(III) at high III + III - acid buffer (pH 5.5), and 0.5 mL of ammonium fluoride [Mal]T.Fe (Mal) and Fe (Mal)2 are the major species of III 3- solution (0.1 M) were premixed, followed by addition of 1 FMCs at pH 3.0 whereas Fe (Mal)3 seems negligible under mL of the sample solution.
Load more

Recommended publications
  • (III)EDTA and Bb4fe(III)KDTA
    FHOTODBCCUK»I*ION 07 THE lSKTLB?IDIlM2SlTET»UC£TATCrXRRAT£(HI) I0H *y CHARLES EEWABD GCDSEY B. S., laehbttrn University, 1957 A SDBSXS submitted in partial fulfillment of the requirement* for the degree MASTER Of SCIENCE Department of Chemistry KANSAS STATS UNIVERSITT 07 AGRICULTURE AKD APHJED SCIENCE 1959 TH QogUAU^-* taBLE oy Q0ITIHT8 INTBGDUCTIOI X EXEKBIMISTAI, * Beagente 3 Equipment • 3 Magnetic Susceptibility Meaeuremente 4 Preparation of B&taeeium Bromide Sitka 4 Preparation of OTedlOEDTA 5 Preparation of HB^FodlDEDTA • Determination of Structure of Hye(III)EDTA and BB4Fe(III)KDTA ... 6 Ultraviolet Radiation of HFo(III)EDT* . 10 Attempted hemoval of Carbon Dioxide from Potaaaitn Bromide Diek . 13 DI8CU8SI0I 1? Structure of Kie(III)SDTA and NB^eUlDEDTA 17 Effects of Radiation of HJe(III)MffA 18 SUMKABY AND CONCLUSIONS 19 ACKNOWLEDGMENT 23 LITEBATUBE CITED 34 ) IHTfiODUCTION than the ethylenediaminetetraacetatoferrateUII) ion, ?«(II2)£DTa~, it radiated with ultraviolet light, the Je(III) la reduced to Je(II). The photoeensltivity of thle complex has been noted by Iambert, et el., (11) and compared to the photosensitivity of other metal chelates. Jones and Long (8) have noted the photosensitivity of the complex formed between xe(lll) and di-sodium SMC* and have proposed the following scheme for the photodecompoeltlon: (1) ie(III)iaWA- • light - Fe(ll)JSDTA— 4 decompoeitlon products (3) *e(II)IOTA-" i H8 + | 0* - Fa(lII)IDTA- (XT (3) Repeated photoreductlon and oxidation leads to the formation of re(0H)(II2)EMft"" and eventually Fe(0H) 3 . Hill-Cottingham (7) has Investigated the photoreductlon of Fe(III)H»A- spectrophotometrlcally and has found that the EOTA chelate Is decomposed on exposure to daylight.
    [Show full text]
  • WO 2016/074683 Al 19 May 2016 (19.05.2016) W P O P C T
    (12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (19) World Intellectual Property Organization International Bureau (10) International Publication Number (43) International Publication Date WO 2016/074683 Al 19 May 2016 (19.05.2016) W P O P C T (51) International Patent Classification: (81) Designated States (unless otherwise indicated, for every C12N 15/10 (2006.01) kind of national protection available): AE, AG, AL, AM, AO, AT, AU, AZ, BA, BB, BG, BH, BN, BR, BW, BY, (21) International Application Number: BZ, CA, CH, CL, CN, CO, CR, CU, CZ, DE, DK, DM, PCT/DK20 15/050343 DO, DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT, (22) International Filing Date: HN, HR, HU, ID, IL, IN, IR, IS, JP, KE, KG, KN, KP, KR, 11 November 2015 ( 11. 1 1.2015) KZ, LA, LC, LK, LR, LS, LU, LY, MA, MD, ME, MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI, NO, NZ, OM, (25) Filing Language: English PA, PE, PG, PH, PL, PT, QA, RO, RS, RU, RW, SA, SC, (26) Publication Language: English SD, SE, SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM, TN, TR, TT, TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, ZW. (30) Priority Data: PA 2014 00655 11 November 2014 ( 11. 1 1.2014) DK (84) Designated States (unless otherwise indicated, for every 62/077,933 11 November 2014 ( 11. 11.2014) US kind of regional protection available): ARIPO (BW, GH, 62/202,3 18 7 August 2015 (07.08.2015) US GM, KE, LR, LS, MW, MZ, NA, RW, SD, SL, ST, SZ, TZ, UG, ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, RU, (71) Applicant: LUNDORF PEDERSEN MATERIALS APS TJ, TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, [DK/DK]; Nordvej 16 B, Himmelev, DK-4000 Roskilde DK, EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU, (DK).
    [Show full text]
  • Applications of Triplet-Photosensitizers and Development of Photochemical Methods
    Portland State University PDXScholar Dissertations and Theses Dissertations and Theses 1-14-2020 Applications of Triplet-Photosensitizers and Development of Photochemical Methods Luke V. Lutkus Portland State University Follow this and additional works at: https://pdxscholar.library.pdx.edu/open_access_etds Part of the Chemistry Commons Let us know how access to this document benefits ou.y Recommended Citation Lutkus, Luke V., "Applications of Triplet-Photosensitizers and Development of Photochemical Methods" (2020). Dissertations and Theses. Paper 5417. https://doi.org/10.15760/etd.7290 This Dissertation is brought to you for free and open access. It has been accepted for inclusion in Dissertations and Theses by an authorized administrator of PDXScholar. Please contact us if we can make this document more accessible: [email protected]. Applications of Triplet-Photosensitizers and Development of Photochemical Methods by Luke V. Lutkus A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemistry Dissertation Committee: Theresa McCormick, Chair Mark Woods Rob Strongin Erik Sanchez Portland State University 2020 Abstract Photochemistry focuses on various aspects of the interaction of light with molecules. This work entails new methodology for fundamental measurements of photochemistry along with novel applications of triplet-photosenstizers. Herein described are two separate methodologies developed for the determination of the quantum yield. A method for the singlet oxygen quantum yield was developed that utilizes the reaction between singlet oxygen and dimethyl sulfoxide (DMSO) to produce dimethyl sulfone. The rate of the reaction is measured by the pressure decrease that results from the consumption of oxygen from the headspace of a sealed system.
    [Show full text]
  • Real-Time Studies of Iron Oxalate-Mediated Oxidation of Glycolaldehyde As a Model for Photochemical Aging of Aqueous Tropospheric Aerosols † ‡ ¶ ‡ § ‡ ∥ § Daniel A
    Article pubs.acs.org/est Real-Time Studies of Iron Oxalate-Mediated Oxidation of Glycolaldehyde as a Model for Photochemical Aging of Aqueous Tropospheric Aerosols † ‡ ¶ ‡ § ‡ ∥ § Daniel A. Thomas, Matthew M. Coggon, , Hanna Lignell, , Katherine A. Schilling, , Xuan Zhang, § ‡ § ‡ § † Rebecca H. Schwantes, Richard C. Flagan, , John H. Seinfeld, , and J. L. Beauchamp*, † Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States ‡ Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States § Environmental Science and Engineering, California Institute of Technology, Pasadena, California 91125, United States *S Supporting Information ABSTRACT: The complexation of iron(III) with oxalic acid in aqueous solution yields a strongly absorbing chromophore that undergoes efficient photodissociation to give iron(II) and the carbon dioxide anion radical. Importantly, iron(III) oxalate complexes absorb near-UV radiation (λ > 350 nm), providing a potentially powerful source of oxidants in aqueous tropospheric chemistry. Although this photochemical system has been studied extensively, the mechanistic details associated with its role in the oxidation of dissolved organic matter within aqueous aerosol remain largely unknown. This study utilizes glycolaldehyde as a model organic species to examine the oxidation pathways and evolution of organic aerosol initiated by the photodissociation of aqueous iron(III) oxalate complexes. Hanging droplets (radius 1 mm) containing iron(III), oxalic acid, glycolaldehyde, and ammonium sulfate (pH ∼3) are exposed to irradiation at 365 nm and sampled at discrete time points utilizing field-induced droplet ionization mass spectrometry (FIDI-MS). Glycolaldehyde is found to undergo rapid oxidation to form glyoxal, glycolic acid, and glyoxylic acid, but the formation of high molecular weight oligomers is not observed.
    [Show full text]
  • Cyclic Voltammetry, Kinetics, Thermodynamic and Molecular Docking Parameters for the Interaction of Nickel Chloride with Diphenylthiocarbazone
    Open Academic Journal of Advanced Science and Technology ISSN 2577-7807 Vol. 4, No. 2, pp. 30-44. 2020 DOI: 10.33094/5.2017.2020.42.30.44 © 2020 by the authors; licensee Online Academic Press, USA Cyclic Voltammetry, Kinetics, Thermodynamic and Molecular Docking Parameters for the Interaction of Nickel Chloride with Diphenylthiocarbazone Esam.A.Gomaa1* Adel.Z. EL-Sonbati2 Mostafa.A.Diab3 Mohamed.S.EL-Ghareib4 Hanaa.M.Salama5 1Chemistry Department, Faculty of Abstract Science, Mansoura University, Mansoura, Egypt. The electrochemical behavior of nickel chloride in citric acid aqueous solution (0.1M) in the presence of potassium ferrioxalate K3Fe(Oxalate)3 2,3Chemistry Department, Faculty of (KFOx) as moderator sensor and by the use of gold working electrode Science, Damietta University, (GWE) was studied. Since nickel ions do not show any peaks in acidic media, Damietta, Egypt. but after adding potassium ferrioxalate K3Fe(Oxalate)3 (KFOx) as a sensor, 4,5Chemistry Department, Faculty of Science, Port Said University, Port two redox peaks of nickel ions were obtained. (KFOx) sensor indicating the Said, Egypt. appearance of nickel ion peaks. Two redox couples of waves were obtained attributed to [Ni(II)-Ox-Fe(III)]/[Ni(III)-Ox-Fe(III)]and[Ni(II)-Ox- Fe(III)] /[Ni(II)-Ox-Fe(II)]. The cyclic voltammetry for NiCl2 and its Licensed: interaction with diphenylthiocarbazone, dithizone was studies at three This work is licensed under a Creative different temperatures, 293.15, 303.15 and 313.15K. Different Commons Attribution 4.0 License. thermodynamic and kinetic parameters of interaction of nickel ions with dithizone were evaluated from the cyclic voltammograms.
    [Show full text]
  • Photodegradation of (E)- and (Z)-Endoxifen Kinetics, By-Products
    PHOTODEGRADATION OF (E)- AND (Z)-ENDOXIFEN: KINETICS, BY-PRODUCTS IDENTIFICATION AND TOXICITY ASSESSMENT A Thesis Submitted to the Graduate Faculty of the North Dakota State University of Agriculture and Applied Science By Marina Arino Martin In Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE Major Program: Environmental and Conservational Sciences February 2018 Fargo, North Dakota North Dakota State University Graduate School Title Photodegradation of (E)- and (Z)-Endoxifen in Water by UV-light and Natural Sunlight: Kinetics, Photodegradation By-product, Toxicity Assessment, and Acute Toxicity Study. By Marina Arino Martin The Supervisory Committee certifies that this disquisition complies with North Dakota State University’s regulations and meets the accepted standards for the degree of MASTER OF SCIENCE SUPERVISORY COMMITTEE: Eakalak Khan Chair John McEvoy Thomas DeSutter Approved: April 13, 2018 Craig Stockwell Date Department Chair ABSTRACT Endoxifen is an effective metabolite of tamoxifen, a commonly used chemotherapy drug, and has been detected at the final effluent of a municipal wastewater treatment plant (WWTP). Its presence in the environment could bring negative effects to aquatic lives. This research investigated the use of ultraviolet radiation (253.7 nm) and natural sunlight to photodegrade endoxifen in water and wastewater, the generation of photodegradation by-products (PBPs) and their toxicity. Endoxifen concentration in water was reduced by 99.1% after 35 seconds of UV light generating two toxic PBPs. Experiments in wastewater at UV light doses used for disinfection resulted in reduction of endoxifen by 30 to 71%. Endoxifen concentration in wastewater was reduced by at least 83% after 150 minutes of solar radiation generating eight PBPs.
    [Show full text]
  • Accurate Measurement of the Photon Flux Received Inside Two
    Accurate Measurement of the Photon Flux Received Inside Two Continuous Flow Microphotoreactors by Actinometry Tristan Aillet, Karine Loubiere, Odile Dechy-Cabaret, Laurent E. Prat To cite this version: Tristan Aillet, Karine Loubiere, Odile Dechy-Cabaret, Laurent E. Prat. Accurate Measurement of the Photon Flux Received Inside Two Continuous Flow Microphotoreactors by Actinometry. International Journal of Chemical Reactor Engineering, De Gruyter, 2014, vol. 12 (n° 1), pp. 1-13. 10.1515/ijcre- 2013-0121. hal-01153086 HAL Id: hal-01153086 https://hal.archives-ouvertes.fr/hal-01153086 Submitted on 19 May 2015 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Open Archive TOULOUSE Archive Ouverte (OATAO) OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao.univ-toulouse.fr/ Eprints ID : 11825 To link to this article : DOI:10.1515/ijcre-2013-0121 URL : http://dx.doi.org/10.1515/ijcre-2013-0121 To cite this version : Aillet, Tristan and Loubiere, Karine and Dechy-Cabaret, Odile and Prat, Laurent E. Accurate Measurement of the Photon Flux Received Inside Two Continuous Flow Microphotoreactors by Actinometry.
    [Show full text]
  • Semiconductor Photocatalysis: Mechanisms, Photocatalytic Performances and Lifetime of Redox Carriers
    University of Kentucky UKnowledge Theses and Dissertations--Chemistry Chemistry 2017 SEMICONDUCTOR PHOTOCATALYSIS: MECHANISMS, PHOTOCATALYTIC PERFORMANCES AND LIFETIME OF REDOX CARRIERS Ruixin Zhou University of Kentucky, [email protected] Author ORCID Identifier: https://orcid.org/0000-0002-2405-4893 Digital Object Identifier: https://doi.org/10.13023/ETD.2017.394 Right click to open a feedback form in a new tab to let us know how this document benefits ou.y Recommended Citation Zhou, Ruixin, "SEMICONDUCTOR PHOTOCATALYSIS: MECHANISMS, PHOTOCATALYTIC PERFORMANCES AND LIFETIME OF REDOX CARRIERS" (2017). Theses and Dissertations--Chemistry. 85. https://uknowledge.uky.edu/chemistry_etds/85 This Doctoral Dissertation is brought to you for free and open access by the Chemistry at UKnowledge. It has been accepted for inclusion in Theses and Dissertations--Chemistry by an authorized administrator of UKnowledge. For more information, please contact [email protected]. STUDENT AGREEMENT: I represent that my thesis or dissertation and abstract are my original work. Proper attribution has been given to all outside sources. I understand that I am solely responsible for obtaining any needed copyright permissions. I have obtained needed written permission statement(s) from the owner(s) of each third-party copyrighted matter to be included in my work, allowing electronic distribution (if such use is not permitted by the fair use doctrine) which will be submitted to UKnowledge as Additional File. I hereby grant to The University of Kentucky and its agents the irrevocable, non-exclusive, and royalty-free license to archive and make accessible my work in whole or in part in all forms of media, now or hereafter known.
    [Show full text]
  • Kinetics of Photoreduction of Ferri- Oxalat E - Deactivation and Inner Filter Caused by Ammoniummolybdate*
    @@ KINETICS OF PHOTOREDUCTION OF FERRI- OXALAT E - DEACTIVATION AND INNER FILTER CAUSED BY AMMONIUMMOLYBDATE* - Tadashi SHIROTSUKA and Hideo NISHIUMI Department of Applied Chemistry, Waseda University, Tokyo, Japan The kinetics of photoreduction of potassium ferrioxalate in the presence of ammoni- ummolybdate was studied at 365 6m//. Measurementswere madein a batchwise and parallel-beam reactor operated at atmospheric pressure and at room temperature. The concentrations of potassium ferrioxalate and ammoniummolybdate were changed from 6.17X10 8 to 3.45xlO"6 and from 2.94xlO"8 to 5.07X10"8 mol/cm3, respective- ly. The decrease in the reaction rate can be explained by the mechanism in which addi- tion of ammoniummolybdate causes both deactivation and inner filter. The ratio of the rate constant of deactivation, ko, to that of the forward reaction, k±9 was 12.5 at 365/6m//. The effect of the inner filter accompanied by addition of a substance on conversion is negligible when the optical thickness of all absorbing substances, r(c+//*), is very much smaller than 1. Undesirable wavelengths causing useless photo- that the addition of ammoniummolybdate caused a chemical side reactions or opaque tar from poly- decrease in the quantum efficiencies, which were en- chromatic light of a light source can be isolated by tirely dependent on the concentrations of both am- several methods: filter solution7), filter glass8), or a moniummolybdate and the reactant. fluorescent substance mixed in cooling water6). But The objectives of this paper are to present data on these are not the best industrial methods, because they the photoreduction of potassium ferrioxalate in the reduce not only undesirable radiation, but also a sig- presence ofammoniummolybdateand to obtain a rate nificant amount of effective radiation for a photo- equation based on reaction mechanismin order to chemical reaction.
    [Show full text]
  • Mechanism of Ferric Oxalate Photolysis
    Mechanism of Ferric Oxalate Photolysis David. M. Mangiante², Richard D. Schaller³ , Piotr Zarzycki²§ , Jillian F. Banfield²∥, and Benjamin Gilbert *² ² Energy Geosciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States ³ Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Building 440, Argonne, Illinois 60439, United States § Institute of Physical Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Poland ∥ Department of Earth and Planetary Science, University of California, Berkeley, Berkeley, California 94720, United States ACS Earth Space Chem., 2017, 1 (5), pp 270±276 DOI: 10.1021/acsearthspacechem.7b00026 Publication Date (Web): June 8, 2017 *E-mail: [email protected]. Abstract 3+ 3± Iron(III) oxalate, Fe (C2O4)3 , is a photoactive metal organic complex found in natural systems and used to quantify photon flux as a result of its high absorbance and reaction quantum yield. It also serves as a model complex to understand metal carboxylate complex photolysis because the mechanism of photolysis and eventual production of CO2 is not well understood for any system. We employed pump/probe mid-infrared transient absorption spectroscopy to study the photolysis reaction of the iron(III) oxalate ion in D2O and H2O up to 3 ns following photoexcitation. We find that intramolecular electron transfer from oxalate to iron occurs on a sub-picosecond time scale, creating iron(II) complexed by one oxidized and two spectator oxalate ligands. Within 40 ps following electron transfer, the oxidized oxalate molecule dissociates to form free solvated CO2(aq)and a species inferred · ± to be CO2 based on the appearance of a new vibrational absorption band and ab initio simulation.
    [Show full text]
  • Architectures Multi-Photochromiques: Structures Et Fonctions
    Architectures multi-photochromiques : structures et fonctions Agostino Galanti To cite this version: Agostino Galanti. Architectures multi-photochromiques : structures et fonctions. Theoretical and/or physical chemistry. Université de Strasbourg, 2018. English. NNT : 2018STRAF046. tel-02083921 HAL Id: tel-02083921 https://tel.archives-ouvertes.fr/tel-02083921 Submitted on 29 Mar 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. UNIVERSITÉ DE STRASBOURG ÉCOLE DOCTORALE DES SCIENCES CHIMIQUES UMR 7006 – Institut de Science et d’Ingénierie Supramoléculaires (I.S.I.S) THÈSE présentée par : Agostino GALANTI soutenue le : 4 Décembre 2018 pour obtenir le grade de : Docteur de l’université de Strasbourg Discipline/ Spécialité : Chimie / Chimie physique Multi-Photochromic Architectures: from Structure to Function THÈSE dirigée par : M. SAMORÌ Paolo Professeur, Université de Strasbourg RAPPORTEURS : M. DE FEYTER Steven Professeur, Katholieke Universiteit Leuven M. MONTALTI Marco Professeur, Università di Bologna AUTRES MEMBRES DU JURY : M. HERMANS Thomas Maître de conférences, Université de Strasbourg L’objectif de cette thèse a été axé sur le développement des systèmes capable de répondre à des stimuli externes, basés sur des unités photochromiques. Au cours des dernières décennies, d’énormes progrès ont été effectués quant à la réalisation des systèmes synthétiques contenant des interrupteurs moléculaires contrôlables à distance, notamment en utilisant préférentiellement la lumière comme stimulus.
    [Show full text]
  • Photolysis of Alkaline Earth Metal Tris(Oxalato)Ferrates(III): a Mossbauer Study
    Indian Journal of Chemistry Vol. 25A. January 1986, pp. 23-25 Photolysis of Alkaline Earth Metal Tris(oxalato)ferrates(III): A Mossbauer Study AS BRAR·, S BRAR & S S SANDHUt Chemistry Department, Indian Institute of Technology. New Delhi 110016 Received 19 April 1984; revised and accepted 30 August 1985 Photolysis of alkaline earth metal tris(oxalato)ferrates(llI) in solid and liquid states has been investigated using Mossbaucr and electronic spectroscopy. Iron(l I) species is formed in solid as well as liquid state. The effect of outer cations. viz. Mg, Ca. Sr and Ba has been observed on the formation of intermediates and quantum yields for Fe(II) species in the liquid state. In earlier papers the effect of outer cations (Li, Na, K, Results and Discussion Cs) on the photolysis and radiolysis of alkali metal Mossbauer parameters, IR data and magnetic moments tristoxalatojferratestl ll)"? and alkali metal of trisioxalato )ferrates(III) of alkaline earth bis'citratojferrates lf l):' in solid and liquid phases was M~ssbauer spectra of the alkaline earth metal reported. The photolysis of hexamminecobalt(III)tris- tris(oxalato)ferrates(III) of Mg, Ca, Sr and Ba are (oxalato)ferrate(III) has also been reported." As an broad, due to spin-lattice relaxation effect? The isomer extension the effect of outer cations, viz. Mg. Ca, Sr. shift value for magnesium, calcium, strontium and and Ba on the products of photolysis of alkaline earth barium tris(oxalato)ferrates(llI) are 0.24. 0.26. 0.25 tris(oxalato)ferrates(I1I) and a comparison of results and 0.31 mms-I respectively, the values for strontium with those of potassium ferrioxalate are reported in and barium tris(oxalato)ferrates(lII) being close to this paper.
    [Show full text]