Abstract
Recently, a photochemical process induced by ultraviolet (UV), vacuum UV (VUV), and iodide (I−) has gained attention for its robust potential for contaminant degradation. However, the mechanisms behind this process remain unclear because both oxidizing and reducing reactants are likely generated. To better understand this process, this study examined the evolutions of hydrogen peroxide (H2O2) and iodine species (i.e., iodide, iodate, and triiodide) during the UV/VUV/I− process under varying pH and dissolved oxygen (DO) conditions. Results show that increasing DO in water enhanced H2O2 and iodate production, suggesting that high DO favors the formation of oxidizing species. In contrast, increasing pH (from 6.0 to 11.0) resulted in lower H2O2 and iodate formation, indicating that there was a decrease of oxidative capacity for the UV/VUV/I− process. In addition, difluoroacetic acid (DFAA) was used as an exemplar contaminant to verify above observations. Although its degradation kinetics did not follow a constant trend as pH increases, the relative importance of mineralization appeared declining, suggesting that there was a redox transition from an oxidizing environment to a reducing environment as pH rises. The treatability of the UV/VUV/I− process was stronger than UV/VUV under pH of 11.0, while UV/VUV process presented a better performance at pH lower than 11.0.
Similar content being viewed by others
References
Abbaszadeh Haddad F, Moussavi G, Moradi M (2019). Advanced oxidation of formaldehyde in aqueous solution using the chemical-less UVC/VUV process: Kinetics and mechanism evaluation. Journal of Water Process Engineering, 27: 120–125
Alapi T, Schrantz K, Arany E, Kozmér Z (2017). Advanced Oxidation Processes for Water Treatment: Fundamentals and Applications. London: IWA Publishing
Buxton G V, Greenstock C L, Helman W P, Ross A B (1988). Critical Review of rate constants for reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals (· OH/ · O−) in aqueous solution. Journal of Physical and Chemical Reference Data, 17(2): 513–886
Chen Y, Wang J, Chen B, Wang L (2019). A green and robust method to measure nanomolar dissolved organic nitrogen (DON) by vacuum ultraviolet. Chemical Engineering Journal, 363: 57–63
Cui J, Gao P, Deng Y (2020). Destruction of per- and polyfluoroalkyl substances (PFAS) with advanced reduction processes (ARPs): A critical review. Environmental Science and Technology, 54(7): 3752–3766
Deng J, Shao Y S, Gao N Y, Xia S J, Tan C Q, Zhou S Q, Hu X H (2013). Degradation of the antiepileptic drug carbamazepine upon different UV-based advanced oxidation processes in water. Chemical Engineering Journal, 222: 150–158
Diesen V, Jonsson M (2014). Formation of H2O2 in TiO2 photocatalysis of oxygenated and deoxygenated aqueous systems: A probe for photocatalytically produced hydroxyl radicals. Journal of Physical Chemistry C, 118(19): 10083–10087
Dorgerloh U, Becker R, Kaiser M (2019). Evidence for the formation of difluoroacetic acid in chlorofluorocarbon-contaminated ground water. Molecules (Basel, Switzerland), 24(6): 1039–1045
Fan X, Tao Y, Wei D, Zhang X, Lei Y, Noguchi H (2015). Removal of organic matter and disinfection by-products precursors in a hybrid process combining ozonation with ceramic membrane ultrafiltration. Frontiers of Environmental Science & Engineering, 9(1): 112–120
Giri R R, Ozaki H, Guo X, Takanami R, Taniguchi S (2014). Oxidative-reductive photodecomposition of perfluorooctanoic acid in water. International Journal of Environmental Science and Technology, 11(5): 1277–1284
Gonzalez M G, Oliveros E, Worner M, Braun A M (2004). Vacuum-ultraviolet photolysis of aqueous reaction systems. Journal of Photochemistry and Photobiology C, Photochemistry Reviews, 5(3): 225–246
Gorka A P, Schnermann M J (2016). Harnessing cyanine photooxidation: From slowing photobleaching to near-IR uncaging. Current Opinion in Chemical Biology, 33: 117–125
Gu Y, Liu T, Wang H, Han H, Dong W (2017). Hydrated electron based decomposition of perfluorooctane sulfonate (PFOS) in the VUV/sulfite system. The Science of the Total Environment, 607–608: 541–548
He D, Yang Y, Tang J, Zhou K, Chen W, Chen Y, Dong Z (2019). Synergistic effect of TiO2-CuWO4 on the photocatalytic degradation of atrazine. Environmental Science and Pollution Research International, 26(12): 12359–12367
Li J, Zhang Q, Chen B, Wang L, Zhu R, Yang J (2021). Hydrogen peroxide formation in water during the VUV/UV irradiation process: Impacts and mechanisms of selected anions. Environmental Research, 195: 110751
Li X, Fang J, Liu G, Zhang S, Pan B, Ma J (2014). Kinetics and efficiency of the hydrated electron-induced dehalogenation by the sulfite/UV process. Water Research, 62: 220–228
Liu X, Vellanki B P, Batchelor B, Abdel-Wahab A (2014). Degradation of 1,2-dichloroethane with advanced reduction processes (ARPs): Effects of process variables and mechanisms. Chemical Engineering Journal, 237: 300–307
Liu X, Yoon S, Batchelor B, Abdel-Wahab A (2013). Photochemical degradation of vinyl chloride with an advanced reduction process (ARP): Effects of reagents and pH. Chemical Engineering Journal, 215–216: 868–875
Liu Z, Bentel M J, Yu Y, Ren C, Gao J, Pulikkal V F, Sun M, Men Y, Liu J (2021). Near-quantitative defluorination of perfluorinated and fluorotelomer carboxylates and sulfonates with integrated oxidation and reduction. Environmental Science & Technology, 55(10): 7052–7062
Li X, Li Z, Xing Z, Song Z, Ye B, Wang Z, Wu Q (2020). UV-LED/P25-based photocatalysis for effective degradation of isothiazolone biocide. Frontiers of Environmental Science & Engineering, 15(5): 85
Li W, Ding Y, Sui Q, Lu S, Qiu Z, Lin K (2012). Identification and ecotoxicity assessment of intermediates generated during the degradation of clofibric acid by advanced oxidation processes. Frontiers of Environmental Science & Engineering, 6(4): 445–454
Meunier S M, Todorovic B, Dare E V, Begum A, Guillemette S, Wenger A, Saxena P, Campbell J L, Sasges M, Aucoin M G (2016). Impact of dissolved oxygen during UV-irradiation on the chemical composition and function of CHO cell culture media. PLoS One, 11(3): e0150957
Moradi M, Moussavi G (2018). Investigation of chemical-less UVC/VUV process for advanced oxidation of sulfamethoxazole in aqueous solutions: Evaluation of operational variables and degradation mechanism. Separation and Purification Technology, 190: 90–99
Moussavi G, Rezaei M (2017). Exploring the advanced oxidation/reduction processes in the VUV photoreactor for dechlorination and mineralization of trichloroacetic acid: Parametric experiments, degradation pathway and bioassessment. Chemical Engineering Journal, 328: 331–342
Motohashi N, Saito Y (1993). Competitive measurement of rate constants for hydroxyl radical reactions using radiolytic hydroxylation of benzoate. Chemical & Pharmaceutical Bulletin, 41(10): 1842–1845
Nosaka Y, Nosaka A Y (2017). Generation and detection of reactive oxygen species in photocatalysis. Chemical Reviews, 117(17): 11302–11336
Park H, Vecitis C D, Cheng J, Dalleska N F, Mader B T, Hoffmann M R (2011). Reductive degradation of perfluoroalkyl compounds with aquated electrons generated from iodide photolysis at 254 nm. Photochemical & Photobiological Sciences: Official journal of the European Photochemistry Association and the European Society for Photobiology, 10(12): 1945–1953
Pourakbar M, Moussavi G, Shekoohiyan S (2016). Homogenous VUV advanced oxidation process for enhanced degradation and mineralization of antibiotics in contaminated water. Ecotoxicology and Environmental Safety, 125: 72–77
Qu Y, Zhang C, Li F, Chen J, Zhou Q (2010). Photo-reductive defluorination of perfluorooctanoic acid in water. Water Research, 44(9): 2939–2947
Roth O, LaVerne J A (2011). Effect of pH on H2O2 production in the radiolysis of water. The Journal of Physical Chemistry A, 115(5): 700–708
Scott B F, Spencer C, Marvin C H, MacTavish D C, Muir D C G (2002). Distribution of haloacetic acids in the water columns of the Laurentian Great Lakes and Lake Malawi. Environmental Science & Technology, 36(9): 1893–1898
Song M, Wang J, Chen B, Wang L (2017). A Facile, nonreactive hydrogen peroxide (H2O2) detection method enabled by ion chromatography with UV detector. Analytical Chemistry, 89(21): 11537–11544
Sun Z, Zhang C, Chen P, Zhou Q, Hoffmann M R (2017a). Impact of humic acid on the photoreductive degradation of perfluorooctane sulfonate (PFOS) by UV/Iodide process. Water Research, 127: 50–58
Sun Z, Zhang C, Zhao X, Chen J, Zhou Q (2017b). Efficient photoreductive decomposition of N-nitrosodimethylamine by UV/iodide process. Journal of Hazardous Materials, 329: 185–192
Tobien T, Cooper W J, Asmus K D (2000). Natural organic matter and disinfection by-products. Washington, DC: American Chemical Society
Vicente J, Arcas A, Bautista D, Shul’pin G B (1994). Aerobic photooxidation and C-C bond cleavage of the acetylacetonate ligand in (2-arylazo)arylpalladium(II) complexes induced by visible light. Journal of the Chemical Society, Dalton Transactions: Inorganic Chemistry, 10: 1505–1509
Wang L, Niu R, Chen B, Wang L, Zhang G (2017). A comparison of photodegradation kinetics, mechanisms, and products between chlorinated and brominated/iodinated haloacetic acids in water. Chemical Engineering Journal, 330: 1326–1333
Wang L, Zhang Q, Chen B, Bu Y, Chen Y, Ma J, Rosario-Ortiz F L, Zhu R (2020). Some issues limiting photo(cata)lysis application in water pollutant control: A critical review from chemistry perspectives. Water Research, 174: 115605
Wang W L, Wu Q Y, Huang N, Wang T, Hu H Y (2016). Synergistic effect between UV and chlorine (UV/chlorine) on the degradation of carbamazepine: Influence factors and radical species. Water Research, 98: 190–198
Wei Y J, Liu C G, Mo L P (2005). Ultraviolet absorption spectra of iodine, iodide ion and triiodide ion. Spectroscopy and Spectral Analysis, 25(1): 86–88
Xie B H, Shan C, Xu Z, Li X C, Zhang X L, Chen J J, Pan B C (2017). One-step removal of Cr(VI) at alkaline pH by UV/sulfite process: Reduction to Cr(III) and in situ Cr(III) precipitation. Chemical Engineering Journal, 308: 791–797
Yang L, Li M, Li W, Bolton J R, Qiang Z (2018a). A green method to determine VUV (185 nm) fluence rate based on hydrogen peroxide production in aqueous solution. Photochemistry and Photobiology, 94(4): 821–824
Yang M, Jonsson M (2014). Evaluation of the O2 and pH effects on probes for surface bound hydroxyl radicals. Journal of Physical Chemistry C, 118(15): 7971–7979
Yang X Y, Wei H, Xie J C, Wang N, Wei N, Wang J W (2018b). 4th International Conference on Water Resource and Environment. Kaohsiung City, July 17th to 21st, 2018
Yang C, Sun W, Ao X (2019). Bacterial inactivation, DNA damage, and faster ATP degradation induced by ultraviolet disinfection. Frontiers of Environmental Science & Engineering, 14(1): 13
Yeo J, Choi W (2009). Iodide-mediated photooxidation of arsenite under 254 nm irradiation. Environmental Science & Technology, 43(10): 3784–3788
Yu K, Li X, Chen L, Fang J, Chen H, Li Q, Chi N, Ma J (2018). Mechanism and efficiency of contaminant reduction by hydrated electron in the sulfite/iodide/UV process. Water Research, 129: 357–364
Zhang Q, Wang L, Chen B, Chen Y, Ma J (2020). Understanding and modeling the formation and transformation of hydrogen peroxide in water irradiated by 254 nm ultraviolet (UV) and 185 nm vacuum UV (VUV): Effects of pH and oxygen. Chemosphere, 244: 125483
Zhang T Y, Lin Y L, Wang A Q, Tian F X, Xu B, Xia S J, Gao N Y (2016). Formation of iodinated trihalomethanes during UV/chloramination with iodate as the iodine source. Water Research, 98: 199–205
Zoschke K, Börnick H, Worch E (2014). Vacuum-UV radiation at 185 nm in water treatment: A review. Water Research, 52: 131–145
Acknowledgements
We appreciate the financial support of the National Natural Science Foundation of China (Grant No. 51978194) and the Shenzhen Science and Technology Innovation Committee (No. JCYJ20180306171820685), as well as assistance from coworkers in the laboratory including Siyan Hao and Yuanxi Huang.
Author information
Authors and Affiliations
Corresponding author
Additional information
Highlights
• UV/VUV/I induces substantial H2O2 and IO3 formation, but UV/I does not.
• Increasing DO level in water enhances H2O2 and iodate productions.
• Increasing pH decreases H2O2 and iodate formation and also photo-oxidation.
• The redox potentials of UV/VUV/I and UV/VUV changes with pH changes.
• The treatability of the UV/VUV/I process was stronger than UV/VUV at pH 11.0.
Supporting information
11783_2021_1489_MOESM1_ESM.pdf
Toward better understanding vacuum ultraviolet—iodide induced photolysis via hydrogen peroxide formation, iodine species change, and difluoroacetic acid degradation
Rights and permissions
About this article
Cite this article
Yang, Y., Zhang, Q., Chen, B. et al. Toward better understanding vacuum ultraviolet—iodide induced photolysis via hydrogen peroxide formation, iodine species change, and difluoroacetic acid degradation. Front. Environ. Sci. Eng. 16, 55 (2022). https://doi.org/10.1007/s11783-021-1489-0
Received:
Revised:
Accepted:
Published:
DOI: https://doi.org/10.1007/s11783-021-1489-0