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Open AccessArticle

A Comparative Study of Microcystin-LR Degradation by UV-A, Solar and Visible Light Irradiation Using Bare and C/N/S-Modified Titania

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Nanomaterials and Nanotechnology Department, Central Metallurgical Research and Development Institute (CMRDI) P.O. Box: 87 Helwan, Cairo 11421, Egypt
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Institute of Technical Chemistry, Photocatalysis and Nanotechnology Research Unit, Leibniz Universität Hannover, Callinstr. 3, D-30167 Hannover, Germany
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Institute for Catalysis, Hokkaido University, N21, W10, Sapporo 001-0021, Japan
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Chemistry Department, Faculty of Science, Ain Shams University, 11566 Abassia, Cairo, Egypt
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Laboratory Photoactive Nanocomposite Materials (Director), Saint-Petersburg State University, Ulyanovskaya str. 1, Peterhof, 198504 Saint-Petersburg, Russia
*
Author to whom correspondence should be addressed.
Catalysts 2019, 9(11), 877; https://doi.org/10.3390/catal9110877
Received: 19 September 2019 / Revised: 16 October 2019 / Accepted: 20 October 2019 / Published: 23 October 2019
In an endeavor to tackle environmental problems, the photodegradation of microcystin-LR (MC-LR), one of the most common and toxic cyanotoxins, produced by the cyanobacteria blooms, was examined using nanostructured TiO2 photocatalysts (anatase, brookite, anatase–brookite, and C/N/S co-modified anatase–brookite) under UV-A, solar and visible light irradiation. The tailoring of TiO2 properties to hinder the electron–hole recombination and improve MC-LR adsorption on TiO2 surface was achieved by altering the preparation pH value. The highest photocatalytic efficiency was 97% and 99% with degradation rate of 0.002 mmol L−1 min−1 and 0.0007 mmol L−1 min−1 under UV and solar irradiation, respectively, using a bare TiO2 photocatalyst prepared at pH 10 with anatase to brookite ratio of ca. 1:2.5. However, the bare TiO2 samples were hardly active under visible light irradiation (<25%) due to a large band gap. Upon UV, solar and vis irradiation, the complete MC-LR degradation (100%) was obtained in the presence of C/N/S co-modified TiO2 with a degradation rate constant of 0.26 min−1, 0.11 min−1 and 0.04 min−1, respectively. It was proposed that the remarkable activity of co-modified TiO2 might originate from its mixed-phase composition, mesoporous structure, and non-metal co-modification. View Full-Text
Keywords: anatase/brookite; non-metal co-modification; emerging pollutants; cyanotoxins; microcystin-LR; photodecomposition anatase/brookite; non-metal co-modification; emerging pollutants; cyanotoxins; microcystin-LR; photodecomposition
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Khedr, T.M.; El-Sheikh, S.M.; Abdeldayem, H.M.; Ismail, A.A.; Kowalska, E.; Bahnemann, D.W. A Comparative Study of Microcystin-LR Degradation by UV-A, Solar and Visible Light Irradiation Using Bare and C/N/S-Modified Titania. Catalysts 2019, 9, 877.

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