Photocatalytic degradation of cylindrospermopsin under UV-A, solar and visible light using TiO2. Mineralization and intermediate products.
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.
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.
Theodora
T
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
T
Triantis
Water Quality Department, Athens Water Supply and Sewerage Company (EYDAP SA), Oropou 156, 11146 Galatsi, Athens, Greece. Electronic address: kaloudis@eydap.gr.
Triantafyllos
T
Kaloudis
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. Electronic address: hiskia@chem.demokritos.gr.
Anastasia
A
Hiskia
D000470:Alkaloids; D001427:Bacterial Toxins; D002384:Catalysis; D002853:Chromatography, Liquid; D000087522:Cyanobacteria Toxins; D017665:Hydroxyl Radical / Q000737:chemistry; D008027:Light; D010782:Photolysis; D053719:Tandem Mass Spectrometry; D014025:Titanium / Q000737:chemistry* / Q000528:radiation effects*; D014498:Uracil / Q000031:analogs & derivatives* / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*
D000470:Alkaloids; D001427:Bacterial Toxins; D000087522:Cyanobacteria Toxins; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; C089595:cylindrospermopsin; D017665:Hydroxyl Radical; D014498:Uracil; D014025:Titanium
Cylindrospermopsin; Intermediate products; Mineralization; Photocatalysis; Titanium dioxide