Photodegradation of EDTA and NTA in the UV/H20 2 Process

für Naturforschung in cooperation with the Max Planck Society for the Advancement of Science under a Creative Commons Attribution 4.0 International License. Dieses Werk wurde im Jahr 2013 vom Verlag Zeitschrift für Naturforschung in Zusammenarbeit mit der Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. digitalisiert und unter folgender Lizenz veröffentlicht: Creative Commons Namensnennung 4.0 Lizenz. Photodegradation of EDTA and NTA in the UV/H20 2 Process Martin Sörensen, Fritz H. Frimmel* Lehrstuhl für Wasserchemie, Engler-Bunte-Institut, Richard-Willstätter-Alle 5, Universität Karlsruhe, D-76131 Karlsruhe, Deutschland Dedicated to Prof. H. P. Fritz on the occasion o f his retirement Z. Naturforsch. 50b, 1845-1853 (1995); received May 4, 1995 EDTA, NTA, UV/H 2 0 2, Photochemical Degradation The influence of H 2 0 2 on the U V degradation of the broadly used aminopolycarboxylates EDTA and NTA in aqueous solution was investigated. The photochemical degradation in the U V /H 2 0 2 process was compared with classical oxidative treatment of potable water. The German drinking water regulation (Trinkwasserverordnung) was the orientation for all experiments. The Advanced Oxidation Process (AOP) turned out to be superior to the classi­ cal oxidation processes. The photochemical degradation of EDTA and NTA by UV irradiation could be signifi­ cantly stimulated in the presence of H 2 0 2. There was a strong increase in the degradation rate and a decrease in the quantum yield of the aminopolycarboxylates. Experiments with butyl chloride as radical scavenger proved the photolytically generated hydroxyl radicals to be responsible for the increase in the degradation rates. The effect of increasing the degradation rate at higher concentrations of H 2 0 2 was limited, because the steady-state concentrations of the hydroxyl radicals as reactive species, did not increase at the same rate as the initial concentration of H 2 0 2. Low amounts of iron dissolved from the high-grade steel photoreactor walls had a signifi­ cant catalytic effect on the degradation.