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Fotiou T, Triantis TM, Kaloudis T, O'Shea KE, Dionysiou DD, Hiskia A. Assessment of the roles of reactive oxygen species in the UV and visible light photocatalytic degradation of cyanotoxins and water taste and odor compounds using C-TiO2. Water Res 2016; 90:52-61. [PMID: 26724439 DOI: 10.1016/j.watres.2015.12.006] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Revised: 11/30/2015] [Accepted: 12/04/2015] [Indexed: 06/05/2023]
Abstract
Visible light (VIS) photocatalysis has large potential as a sustainable water treatment process, however the reaction pathways and degradation processes of organic pollutants are not yet clearly defined. The presence of cyanobacteria cause water quality problems since several genera can produce potent cyanotoxins, harmful to human health. In addition, cyanobacteria produce taste and odor compounds, which pose serious aesthetic problems in drinking water. Although photocatalytic degradation of cyanotoxins and taste and odor compounds have been reported under UV-A light in the presence of TiO2, limited studies have been reported on their degradation pathways by VIS photocatalysis of these problematic compounds. The main objectives of this work were to study the VIS photocatalytic degradation process, define the reactive oxygen species (ROS) involved and elucidate the reaction mechanisms. We report carbon doped TiO2 (C-TiO2) under VIS leads to the slow degradation of cyanotoxins, microcystin-LR (MC-LR) and cylindrospermopsin (CYN), while taste and odor compounds, geosmin and 2-methylisoborneol, were not appreciably degraded. Further studies were carried-out employing several specific radical scavengers (potassium bromide, isopropyl alcohol, sodium azide, superoxide dismutase and catalase) and probes (coumarin) to assess the role of different ROS (hydroxyl radical OH, singlet oxygen (1)O2, superoxide radical anion [Formula: see text] ) in the degradation processes. Reaction pathways of MC-LR and CYN were defined through identification and monitoring of intermediates using liquid chromatography tandem mass spectrometry (LC-MS/MS) for VIS in comparison with UV-A photocatalytic treatment. The effects of scavengers and probes on the degradation process under VIS, as well as the differences in product distributions under VIS and UV-A, suggested that the main species in VIS photocatalysis is [Formula: see text] , with OH and (1)O2 playing minor roles in the degradation.
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Affiliation(s)
- Theodora Fotiou
- Laboratory of Catalytic - Photocatalytic Processes and Environmental Analysis, Institute of Nanoscience & Nanotechnology, National Center for Scientific Research "Demokritos", Patriarchou Grigoriou & Neapoleos, 15310, Agia Paraskevi, Athens, Greece
| | - Theodoros M Triantis
- Laboratory of Catalytic - Photocatalytic Processes and Environmental Analysis, Institute of Nanoscience & Nanotechnology, National Center for Scientific Research "Demokritos", Patriarchou Grigoriou & Neapoleos, 15310, Agia Paraskevi, Athens, Greece
| | - Triantafyllos Kaloudis
- Water Quality Department, Athens Water Supply and Sewerage Company (EYDAP SA), Oropou 156, 11146, Galatsi, Athens, Greece
| | - Kevin E O'Shea
- Department Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, USA
| | - Dionysios D Dionysiou
- Environmental Engineering and Science Program, Department of Biomedical, Chemical and Environmental Engineering (DBCEE), University of Cincinnati, Cincinnati, OH, 45221-0012, USA
| | - Anastasia Hiskia
- Laboratory of Catalytic - Photocatalytic Processes and Environmental Analysis, Institute of Nanoscience & Nanotechnology, National Center for Scientific Research "Demokritos", Patriarchou Grigoriou & Neapoleos, 15310, Agia Paraskevi, Athens, Greece.
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Antoniou MG, Zhao C, O’Shea KE, Zhang G, Dionysiou DD, Zhao C, Han C, Nadagouda MN, Choi H, Fotiou T, Triantis TM, Hiskia A. CHAPTER 1. Photocatalytic Degradation of Organic Contaminants in Water: Process Optimization and Degradation Pathways. Energy and Environment Series 2016. [DOI: 10.1039/9781782627104-00001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Fotiou T, Triantis T, Kaloudis T, Hiskia A. Photocatalytic degradation of cylindrospermopsin under UV-A, solar and visible light using TiO2. Mineralization and intermediate products. Chemosphere 2015; 119 Suppl:S89-S94. [PMID: 24846598 DOI: 10.1016/j.chemosphere.2014.04.045] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 04/02/2014] [Accepted: 04/03/2014] [Indexed: 06/03/2023]
Abstract
Cyanobacteria (blue-green algae) are considered an important water quality problem, since several genera can produce toxins, called cyanotoxins that are harmful to human health. Cylindrospermopsin (CYN) is an alkaloid-like potent cyanotoxin that has been reported in water reservoirs and lakes worldwide. In this paper the removal of CYN from water by UV-A, solar and visible light photocatalysis was investigated. Two different commercially available TiO2 photocatalysts were used, i.e., Degussa P25 and Kronos-vlp7000. Complete degradation of CYN was achieved with both photocatalysts in 15 and 40 min under UV-A and 40 and 120 min under solar light irradiation, for Degussa P25 and Kronos vlp-7000 respectively. Experiments in the absence of photocatalysts showed that direct photolysis was negligible. Under visible light irradiation only the Kronos vlp-7000 which is a visible light activated catalyst was able to degrade CYN. A number of intermediates were identified and a complete degradation pathway is proposed, leading to the conclusion that hydroxyl radical attack is the main mechanism followed. TOC and inorganic ions (NO2-, NO3-, SO4(2-) and NH4+) determinations suggested that complete mineralization of CYN was achieved under UV-A in the presence of Degussa P25.
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Affiliation(s)
- Theodora Fotiou
- Laboratory of Catalytic - Photocatalytic Processes (Solar Energy - Environment), Institute of Advanced Materials, Physicochemical Processes, Nanotechnology & Microsystems, National Center for Scientific Research "Demokritos", Patriarchou Grigoriou & Neapoleos, 15310 Agia Paraskevi, Athens, Greece
| | - Theodoros Triantis
- Laboratory of Catalytic - Photocatalytic Processes (Solar Energy - Environment), Institute of Advanced Materials, Physicochemical Processes, Nanotechnology & Microsystems, National Center for Scientific Research "Demokritos", Patriarchou Grigoriou & Neapoleos, 15310 Agia Paraskevi, Athens, Greece
| | - Triantafyllos Kaloudis
- Water Quality Department, Athens Water Supply and Sewerage Company (EYDAP SA), Oropou 156, 11146 Galatsi, Athens, Greece.
| | - Anastasia Hiskia
- Laboratory of Catalytic - Photocatalytic Processes (Solar Energy - Environment), Institute of Advanced Materials, Physicochemical Processes, Nanotechnology & Microsystems, National Center for Scientific Research "Demokritos", Patriarchou Grigoriou & Neapoleos, 15310 Agia Paraskevi, Athens, Greece.
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Fotiou T, Triantis TM, Kaloudis T, Papaconstantinou E, Hiskia A. Photocatalytic degradation of water taste and odour compounds in the presence of polyoxometalates and TiO2: Intermediates and degradation pathways. J Photochem Photobiol A Chem 2014. [DOI: 10.1016/j.jphotochem.2014.04.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Kaloudis T, Zervou SK, Tsimeli K, Triantis TM, Fotiou T, Hiskia A. Determination of microcystins and nodularin (cyanobacterial toxins) in water by LC-MS/MS. Monitoring of Lake Marathonas, a water reservoir of Athens, Greece. J Hazard Mater 2013; 263 Pt 1:105-115. [PMID: 23958137 DOI: 10.1016/j.jhazmat.2013.07.036] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 07/04/2013] [Accepted: 07/17/2013] [Indexed: 06/02/2023]
Abstract
A method for the determination of the hepatotoxic cyanotoxins microcystins (MCs, i.e. MC-LR, MC-RR, MC-YR, MC-LA) and nodularin (NOD) in water was developed using liquid chromatography with electrospray ionization triple quadrupole mass spectrometry (LC-ESI-MS/MS) after solid phase extraction (SPE). New patterns of fragmentation of MC-LA were observed under the experimental conditions used. The method was fully validated to meet accreditation criteria. Mean recoveries at three concentration levels (0.006, 0.1 and 1 μg L(-1)) ranged between 70 and 114% with %RSD values generally below 20%. Detection limits were 2 ng L(-1) for all hepatotoxins. The method was applied to study the occurrence of MCs and NOD in Lake Marathonas, a water reservoir of Athens, over a period from July 2007 to December 2010. The protein phosphatase inhibition assay (PPIA) was additionally used for fast screening of samples. MC-YR, MC-LR and MC-RR were detected and found to vary seasonally with consistent peaks during early autumn, having maximum concentrations of 717, 451 and 174 ng L(-1), respectively. The results of this study constitute the first report on the presence, concentration levels and seasonal variations of MCs in Lake Marathonas. None of the target cyanotoxins were detected in treated drinking water samples during the period of the study.
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Affiliation(s)
- Triantafyllos Kaloudis
- Quality Control Department, Athens Water Supply and Sewerage Company (EYDAP SA), Oropou 156, 11146 Galatsi, Athens, Greece
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Fotiou T, Triantis TM, Kaloudis T, Pastrana-Martínez LM, Likodimos V, Falaras P, Silva AM, Hiskia A. Photocatalytic Degradation of Microcystin-LR and Off-Odor Compounds in Water under UV-A and Solar Light with a Nanostructured Photocatalyst Based on Reduced Graphene Oxide–TiO2 Composite. Identification of Intermediate Products. Ind Eng Chem Res 2013. [DOI: 10.1021/ie400382r] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
| | | | - Triantafyllos Kaloudis
- Quality Control Department, Athens Water Supply and Sewerage Company (EYDAP SA), Oropou
156, 11146 Galatsi, Athens, Greece
| | - Luisa M. Pastrana-Martínez
- LCM—Laboratory of Catalysis
and Materials−Associate Laboratory LSRE/LCM, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465
Porto, Portugal
| | | | | | - Adrián M.T. Silva
- LCM—Laboratory of Catalysis
and Materials−Associate Laboratory LSRE/LCM, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465
Porto, Portugal
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Triantis TM, Fotiou T, Kaloudis T, Kontos AG, Falaras P, Dionysiou DD, Pelaez M, Hiskia A. Photocatalytic degradation and mineralization of microcystin-LR under UV-A, solar and visible light using nanostructured nitrogen doped TiO2. J Hazard Mater 2012; 211-212:196-202. [PMID: 22169146 DOI: 10.1016/j.jhazmat.2011.11.042] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 11/09/2011] [Accepted: 11/12/2011] [Indexed: 05/31/2023]
Abstract
In an attempt to face serious environmental hazards, the degradation of microcystin-LR (MC-LR), one of the most common and more toxic water soluble cyanotoxin compounds released by cyanobacteria blooms, was investigated using nitrogen doped TiO(2) (N-TiO(2)) photocatalyst, under UV-A, solar and visible light. Commercial Degussa P25 TiO(2), Kronos and reference TiO(2) nanopowders were used for comparison. It was found that under UV-A irradiation, all photocatalysts were effective in toxin elimination. The higher MC-LR degradation (99%) was observed with Degussa P25 TiO(2) followed by N-TiO(2) with 96% toxin destruction after 20 min of illumination. Under solar light illumination, N-TiO(2) nanocatalyst exhibits similar photocatalytic activity with that of commercially available materials such as Degussa P25 and Kronos TiO(2) for the destruction of MC-LR. Upon irradiation with visible light Degussa P25 practically did not show any response, while the N-TiO(2) displayed remarkable photocatalytic efficiency. In addition, it has been shown that photodegradation products did not present any significant protein phosphatase inhibition activity, proving that toxicity is proportional only to the remaining MC-LR in solution. Finally, total organic carbon (TOC) and inorganic ions (NO(2)(-), NO(3)(-) and NH(4)(+)) determinations confirmed that complete photocatalytic mineralization of MC-LR was achieved under both UV-A and solar light.
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Affiliation(s)
- T M Triantis
- Laboratory of Catalytic - Photocatalytic Processes (Solar Energy - Environment), Institute of Physical Chemistry, National Center for Scientific Research Demokritos, Neapoleos 25, 15310 Agia Paraskevi, Attiki, Greece
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