LED-Based Photocatalytic Treatment of Pesticides and Chlorophenols
Publication: Journal of Environmental Engineering
Volume 139, Issue 9
Abstract
In this paper, light-emitting diodes (LEDs), a novel light source, is reported for the photocatalytic degradation of four known pesticides [2,4-dichlorophenoxyacetic acid (2,4-D), 2-methyl-4-chlorophenoxyacetic acid (MCPA), 4-chlorophenol (4-CP), and 2,4-dichlorophenol (2,4-DCP)] in aqueous solution. 2,4-Dichlorophenoxyacetic acid was further chosen to evaluate the impact of photocatalyst loading and light intensity on the degradation rate. The degradation of 2,4-D under LED irradiation (365 nm) was compared with that using mercury discharge lamp irradiation (350 nm). Irradiation of the different pesticides with a 365-nm LED light source led to their complete mineralization upon prolonged exposure. The degradation rate was slower when mixtures of pesticides were used because of competition between pesticide molecules for adsorption sites, hydroxyl radicals, and holes. A suitable photocatalyst loading was determined to be of ; a linear relationship between the first-order kinetic rate and light intensity (2.7 to approximately 46.5 mW) was observed. A comparison between LEDs and conventional mercury discharge lamps indicated that the former was more energy-efficient.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The writers acknowledge the financial assistance provided by the Natural Science and Engineering Council of Canada to conduct this research through support of the RES’EAU WaterNet strategic research network. The writers also thank Mr. Edward C. Cairns in the electronic workshop and Mr. Andrew Read in the science workshop of the University of Calgary for fabrication of the LED reactor.
References
Andreozzi, R., Caprio, V., Insola, A., and Marotta, R. (1999). “Advanced oxidation processes (AOP) for water purification and recovery.” Catal. Today, 53(1), 51–59.
Augugliaro, V., Palmisano, L., Sclafani, A., Minero, C., and Pelizzetti, E. (1988). “Photocatalytic degradation of phenol in aqueous titanium dioxide dispersions.” Toxicol. Environ. Chem., 16(2), 89–109.
Bhatkhande, D. S., Pangarkar, V. G., and Beenackers, A. A. C. M. (2002). “Photocatalytic degradation for environmental applications—A review.” J. Chem. Technol. Biotechnol., 77(1), 102–116.
Brimble, S., Bacchus, P., and Caux, P. Y. (2005). “Pesticide utilization in Canada: A compilation of current sales and use data.” Environment Canada, Gatineau, QB, Canada.
Calvert, J., and Pitts, J. (1996). Photochemistry, Wiley, New York.
Chen, D. H., Ye, X., and Li, K. (2005). “Oxidation of PCE with a UV LED photocatalytic reactor.” Chem. Eng. Technol., 28(1), 95–97.
Chen, Y., et al. (2011). “Photocatalytic inactivation of Escherichia coli by natural sphalerite suspension: Effect of spectrum, wavelength and intensity of visible light.” Chemosphere, 84(9), 1276–1281.
Exon, J. H. (1984). “A review of chlorinated phenols.” Vet. Hum. Toxicol., 26(6), 508–520.
Fox, M. A., and Dulay, M. T. (1993). “Heterogeneous photocatalysis.” Chem. Rev., 93(1), 341–357.
Ghosh, J. P., Langford, C. H., and Achari, G. (2008). “Characterization of an LED based photoreactor to degrade 4-chlorophenol in an aqueous medium using coumarin (C-343) sensitized .” J. Phys. Chem. A, 112(41), 10310–10314.
Health Canada. (2006). “2-Methyl-4-chlorophenoxyacetic acid (MCPA) in drinking water.” 〈http://www.hc-sc.gc.ca/ewh-semt/consult/_2007/mcpa/chap2-draft-ebauche-eng.php〉 (Mar. 11, 2012).
Health Canada. (2008). “Chlorophenols.” 〈http://www.hc-sc.gc.ca/ewh-semt/pubs/water-eau/chlorophenols/index-eng.php〉 (Mar. 11, 2012).
Health Canada. (2009). “Dichlorophenoxyacetic acid.” 〈http://www.hc-sc.gc.ca/ewh-semt/pubs/water-eau/dichlorophenoxyacetic_acid/guideline-recommandation-eng.php〉 (Mar. 11, 2012).
Hoffmann, M. R., Martin, S. T., Choi, W., and Bahnemann, D. W. (1995). “Environmental applications of semiconductor photocatalysis.” Chem. Rev., 95(1), 69–96.
Huang, X., Wang, H., Yin, S., Chen, X., Chen, W., and Yang, H. (2009). “Sterilization system for air purifier by combining ultraviolet light emitting diodes with .” J. Chem. Technol. Biotechnol., 84(10), 1437–1440.
Kwan, C. Y., and Chu, W. (2004). “A study of the reaction mechanisms of the degradation of 2,4-dichlorophenoxyacetic acid by oxalate-mediated photooxidation.” Water Res., 38(19), 4213–4221.
Linsebigler, A. L., Lu, G., and Yates, J. T. (1995). “Photocatalysis on surfaces: Principles, mechanisms, and selected results.” Chem. Rev., 95(3), 735–758.
Ollis, D. F., Pelizzetti, E., and Serpone, N. (1991). “Photocatalyzed destruction of water contaminants.” Environ. Sci. Technol., 25(9), 1522–1529.
Parsons, S. (2004). Advanced oxidation processes for water and wastewater treatment, International Water Association, London.
Shie, J.-L., Lee, C.-H., Chiou, C.-S., Chang, C.-T., Chang, C.-C., and Chang, C.-Y. (2008). “Photodegradation kinetics of formaldehyde using light sources of UVA, UVC and UVLED in the presence of composed silver titanium oxide photocatalyst.” J. Hazard. Mater., 155(1–2), 164–172.
Theurich, J., Lindner, M., and Bahnemann, D. W. (1996). “Photocatalytic degradation of 4-chlorophenol in aerated aqueous titanium dioxide suspensions: A kinetic and mechanistic study.” Langmuir, 12(26), 6368–6376.
Topalov, A., Abramović, B., Molnár-Gábor, D., Csanádi, J., and Arcson, O. (2001). “Photocatalytic oxidation of the herbicide (4-chloro-2-methylphenoxy) acetic acid (MCPA) over .” J. Photochem. Photobiol. A Chem., 140(3), 249–253.
Wang, W.-Y., and Ku, Y. (2006). “Photocatalytic degradation of Reactive Red 22 in aqueous solution by UV-LED radiation.” Water Res., 40(12), 2249–2258.
Information & Authors
Information
Published In
Journal of Environmental Engineering
Volume 139 • Issue 9 • September 2013
Pages: 1146 - 1151
Copyright
© 2013 American Society of Civil Engineers.
History
Received: Jul 16, 2012
Accepted: May 6, 2013
Published online: Aug 15, 2013
Published in print: Sep 1, 2013
Discussion open until: Jan 15, 2014
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.