Reoxidation of Photoreduced Polyoxotungstate ([PW12O40]4–) by Different Oxidants in the Presence of a Model Pollutant. Kinetics and Reaction Mechanism
Polyoxometalates (POMs) are attractive photocatalysts for water purification. Reoxidation of the photoreduced form of POM by a bulk oxidant is an important step in the cycle yet has received little attention. Photoreduced phosphotungstate ([PW12O40]4–; “POM–”) was reacted with bulk oxidants, XOOX, including hydrogen peroxide (HP), peroxyacetic acid (PAA), peroxymonosulfate (MS), peroxydisulfate (DS), and dioxygen (O2), in the presence of the model pollutant 2-propanol under various conditions, and the stoichiometries and rate laws were established. A unified chain reaction is proposed in which the rate-limiting step is outer-sphere one-electron transfer to XOOX yielding •OX (•OH, SO4•– or CH3CO2•). This step is found to be proton-assisted when the leaving group OX– is a strong base (OH–), but independent of [H+] when the leaving group is a weak base (O2•–, SO42–). The rate of this step follows the order PAA > MS > O2 > HP > DS at pH 1.3, but O2 > PAA > MS > HP > DS at pH 4.1. The chain includes a number of POM–-regenerating steps that, with some bulk oxidants (especially MS and DS), leads to further consumption of bulk oxidant and transformation of pollutant. These steps were identified through effects of conditions on reaction stoichiometry, order with respect to [POM–], and suppression by POM. Chloride ion “short-circuits” the chain by reducing •OX and forming Cl2•–, which scavenges POM–. The results provide insight into POM-catalyzed redox reactions in water purification and selective redox applications.
This article is cited by 12 publications.
- Mooeung Kim, Masoumeh Chamack, Yurii V. Geletii, and Craig L. Hill . Synergetic Catalysis of Copper and Iron in Oxidation of Reduced Keggin Heteropolytungstates by Dioxygen. Inorganic Chemistry 2018, 57 (1) , 311-318. https://doi.org/10.1021/acs.inorgchem.7b02506
- Éva Dóka and Gábor Lente . Modeling Studies of Inhomogeneity Effects during Laser Flash Photolysis Experiments: A Reaction–Diffusion Approach. The Journal of Physical Chemistry A 2017, 121 (14) , 2740-2747. https://doi.org/10.1021/acs.jpca.7b00443
- Mooeung Kim, Ira A. Weinstock, Yurii V. Geletii, and Craig L. Hill . Oxidation of Reduced Keggin Heteropolytungstates by Dioxygen in Water Catalyzed by Cu(II). ACS Catalysis 2015, 5 (12) , 7048-7054. https://doi.org/10.1021/acscatal.5b01771
- Ziru Wang, Hajime Hojo, Hisahiro Einaga. One-step oxidation of benzene to phenol with H3PW12O40 under photoirradiation: Effect of operating conditions. Chemical Engineering Journal 2022, 427 , 131369. https://doi.org/10.1016/j.cej.2021.131369
- Sarit K. Ghosh, Venketa K. Perla, Kaushik Mallick, Tarasankar Pal. Ammonium phosphomolybdate: a material for dielectric crossover and resistive switching performance. Nanoscale Advances 2020, 2 (11) , 5343-5351. https://doi.org/10.1039/D0NA00481B
- Aman Mahajan, Princy Gupta. Halloysite nanotubes based heterogeneous solid acid catalysts. New Journal of Chemistry 2020, 44 (30) , 12897-12908. https://doi.org/10.1039/D0NJ02846K
- Yanhong Sun, Xia Liu. Efficient visible-light photocatalytic degradation of imidacloprid and acetamiprid using a modified carbon nitride/tungstophosphoric acid composite induced by a nucleophilic addition reaction. Applied Surface Science 2019, 485 , 423-431. https://doi.org/10.1016/j.apsusc.2019.04.203
- Neelam, Dan Meyerstein, Ariela Burg, Dror Shamir, Yael Albo. Polyoxometalates entrapped in sol-gel matrices as electron exchange columns and catalysts for the reductive de-halogenation of halo-organic acids in water. Journal of Coordination Chemistry 2018, 71 (19) , 3180-3193. https://doi.org/10.1080/00958972.2018.1515926
- Yanhong Sun, Pengcheng Meng, Xia Liu. Self-assembly of tungstophosphoric acid/acidified carbon nitride hybrids with enhanced visible-light-driven photocatalytic activity for the degradation of imidacloprid and acetamiprid. Applied Surface Science 2018, 456 , 259-269. https://doi.org/10.1016/j.apsusc.2018.06.104
- Nadiia I. Gumerova, Annette Rompel. Synthesis, structures and applications of electron-rich polyoxometalates. Nature Reviews Chemistry 2018, 2 (2) https://doi.org/10.1038/s41570-018-0112
- Samahe Sadjadi, Majid M. Heravi, Mansoureh Daraie. Heteropolyacid supported on amine-functionalized halloysite nano clay as an efficient catalyst for the synthesis of pyrazolopyranopyrimidines via four-component domino reaction. Research on Chemical Intermediates 2017, 43 (4) , 2201-2214. https://doi.org/10.1007/s11164-016-2756-8
- Hooman Rezaei Ghalebi, Soheil Aber, Afzal Karimi. Keggin type of cesium phosphomolybdate synthesized via solid-state reaction as an efficient catalyst for the photodegradation of a dye pollutant in aqueous phase. Journal of Molecular Catalysis A: Chemical 2016, 415 , 96-103. https://doi.org/10.1016/j.molcata.2016.01.031