Rezaei kalanteri R, Dadban shahamat Y, Farzadkia M, Esrafily A. Investigation of Photocatalytic Degradation of Diazinon in Synthetic Wastewater Using Nano -TiO2/UV. JGUMS 2014; 22 (S1) :32-41
URL:
http://journal.gums.ac.ir/article-1-593-en.html
1- Iran University of Medical Sciences
2- Golestan University of Medical Sciences , ydadban@ yahoo.com
Abstract: (9805 Views)
Abstract Introduction:Diazinon is an organophosphorus pesticide used to control a variety of insects in agriculture and it is relatively water soluble, non-polar, moderately mobile and persistent in soil, hence, it is a matter of health concern when using groundwater and surface derived drinking water. Objective: In this study, Photocatalytic degradation of Diazinon was investigated using the nano-TiO2, as a photocatalyst and in aqueous solution. Materials and Methods: The UV source was provided by OSRAM 125W high-pressure mercury lamp and the initial concentration of Diazinon was 40 mgl-1. In this study, the treatment conditions included the presence of UV and aeration, pH, amount of nano-TiO2 and the contact time. For the purpose of pre-concentration and extraction of the Diazinon from the samples, extraction was done using dispersive liquid-liquid microextraction (DLLME) technique and, then, analysis was done by gas chromatography (GC-FID). The extent of Diazinon degradation was also determined by COD measurements by titration of the treated solution with KCr2O7 solution. The toxicity of nano-TiO2 was investigated by daphnia magna bioassay analyses. Results: The kinetics of Diazinon photodegradation was found to follow the first-order rate law and the rate constant was 0.099 (min-1). The optimum conditions for the degradation of Diazinon were found to be pH 8, [nano-TiO2] = 0.2 gl-1 and [time] = 120 min, and the removal efficiency of Diazinon and COD were 99.64% and 65%, respectively. The LC50 (96h) and NOEC (96h) of nano-TiO2 were 1173 and 507 mgl-1, respectively. Conclusion: The results show that the presence of UV and aeration, has a positive effect on Photocatalytic degradation of Diazinon and COD removal and the maximum removal of them were due to UV irradiation, exposure time, aeration and nano-TiO2, respectively. According to the US EPA classification, nano-TiO2 is classified as practically non-toxic.
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Special Received: 2014/04/22 | Accepted: 2014/04/22 | Published: 2014/04/22