Degradation of Imidacloprid in Water by Photo-Fenton and TiO₂ Photocatalysis at a Solar Pilot Plant:  A Comparative Study

Abstract

The technical feasibility, mechanisms, and performance of degradation of aqueous imidacloprid have been studied at pilot scale in two well-defined photocatalytic systems of special interest because natural UV light can be used: heterogeneous photocatalysis with titanium dioxide and homogeneous photocatalysis by photo-Fenton. Equivalent pilot-scale and field conditions used for both allowed adequate comparison of the degree of mineralization and toxicity achieved as well as the transformation products generated in route to mineralization by both systems. Ninety-five percent of mineralization (<2.0 mg/L) was reached after 250 min of photocatalytic treatment with Fenton and 450 min with TiO2, meaning that TOC disappears 2.4 times faster with photo-Fenton photocatalytic treatment than with TiO2. The Daphnia Magna test for final residual TOC does not reveal anytoxic behavior. Transformation products evaluated by GC-MS/AED after two SPE procedures and LC-IC were the same in both cases. The main differences between the two processes are in the amount of transformation products (TPs) generated, not in the TPs detected which were always the same. At the end of both processes low concentration (<0.1 mg/L) of 2 pyrrolidinone (transformation product) remains in the dissolution and around 1 mg/L of formate in the case of photo-Fenton.

Atmospheric cold plasma dissipation efficiency of agrochemicals on blueberries

“…In this study, the degradation of boscalid is likely due to attack of hydroxyl radicals at −H in the three rings (benzene and pyridine rings) leading to four mono and di hydroxylated products and other carboxylic acids (Lagunas-Allué, Martínez-Soria, Sanz-Asensio, Salvador, Ferronato, & Chovelon, 2010). Furthermore, the suggested degradation of imidacloprid is due to the reaction of hydroxyl radicals to form 6-chloronicotinic aldehyde and 6-chloronicotinic acid (Agüera, Almansa, Malato, Maldonado, & Fernández-Alba, 1998;Malato, et al, 2001). …”

Studies on the reaction pathway of arsenate adsorption at water–TiO2 interfaces using density functional theory

“…TiO 2 was chosen as the adsorbent because it is a widely used material in many interface-related studies [21,22] 0021-9797/$ -see front matter Ó 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.jcis.2011.08.040 including the treatment for arsenic pollution [15,23].…”

Comparative Study of Advanced Oxidation Processes to Treat Petroleum Wastewater

“…Zarei et al [6] showed that the removal efficiency of phenol was 69% after 150 min using photoelectro-Fenton (PEF)/Mn 2+ /TiO 2 nanoparticles for the removal of phenol from aqueous solutions. Nogueira [7] showed that the role of Fe 2+ ions and H 2 O 2 are much more important than that of TiO 2 in the photodegradation of both 4-chloro-phenol (4CP) and dichloro-acetic acid (DCA) under solar irradiation [7].…”