Photocatalytic Degradation of Selected s-Triazine Herbicides and Organophosphorus Insecticides over Aqueous TiO₂ Suspensions

Abstract

The photocatalytic degradation of selected s-triazine herbicides and organophosphorus insecticides was carried out in aqueous TiO2 suspensions under simulated solar light. The tested herbicides from the s-triazines group were atrazine, propazine, cyanazine, prometryne, and irgarol. The tested insecticides from the organophosphorus group were ethyl parathion, methyl parathion, ethyl bromophos, methyl bromophos, and diclofenthion. Degradation kinetics followed first-order reaction and has been monitored through gas chromatography. The degradation was fast with half-lives varying from 10.2 to 38.3 min depending on the nature and the structure of compounds. The generated transformation products (TPs) were formed via oxidation, dealkylation, and dechlorination for s-triazines and via oxidation and photohydrolysis for organophosphates. The TPs of irgarol, bromophos, and dichlofenthion were identified using solid-phase extraction (SDB-disks) and GC-MS techniques, and possible degradation routes were proposed showing similar degradation pathways as for other triazines and organophosporus pesticides. This work points out to the necessity of extended knowledge of the successive steps in a solar-assisted detoxification process.

A review of TiO2 nanoparticles

“…The use of TiO 2 for environmental cleanup of organic pollutants through photooxidation has received much attention in the past decade. Various reports have been made on the degradation of pesticides using TiO 2 or modified TiO 2 in solution, as listed in Table 2 [147][148][149][150][151][152][153].…”

Photocatalytic Degradation of Organic Pollutants: Mechanisms and Kinetics

“…A brief summary showing the starting material and by-products under photolytic condition is shown below in Chart 2. Konstantinou et al, 2001a;Pelizzetti et al, 1990Pelizzetti et al, , 1992aPelizzetti et al, , 1992bMinero et al, 1996;Muszkat et al, 1995;Sanlaville et al, 1996, Sleiman et al, 2006 Aniline and Amide derivative Amines, Dechlorinated, Dealkylated, Cyclized, Aliphatics, Cyclized Konstantinou et al, 2001bKonstantinou et al, , 2002Sakkas et al, 2004;Peñuela and Barceló, 1996;Pathirana & Maithreepala, 1997 7 Thicarbamate derivative Amine, Carboxy, Sulfoxide, Dealkylated Vidal et al, 1999;Sturini et al, 1996;Vidal & Martin, 2001 8 Phenoxy-acids derivatives Hydroxylated, Carboxylated, Chlorophenols, Quinonidal Herrmann et al, 1998;Topalov et al, 2000;Barbeni et al, 1987;Poulios et al, 1998;9 Organophosphorus derivatives Hydroxy, Oxon, Phenol, Dialkylated, Trialkyl esters, Fragmented products Herrmann, 1999;Konstantinou et al, 2001a, Oncescu et al, 2010Herrmann et al, 1999;Hua et al, 1995;Sakkas et al, 2002;Dominguez et al, 1998 10 Carbamate derivative Hydroxylated, Decarboxylated, Phenolic, Dealkylated, Cyclized Tamimi et al, 2006;Percerancier et al, 1995;Pramauro et al, 1997;Tanaka et al, 1999;Marinas et al, 2001;Bianco Prevot et al, 199...…”

Photochemischer und photokatalytischer Abbau von Carbamazepin, Clofibrinsäure, Iomeprol und Iopromid

“…Im allgemeinen wird bei der heterogenen Photokatalyse die Abhängigkeit der Abbaurate von der Reaktandenkonzentration formal mit Hilfe der Langmuir-Adsorptionsisotherme bzw. mit der Langmuir-Hinshelwood-Kinetik (L-H-Kinetik) beschrieben [98,118,119,121,[170][171][172][173][174][175][176][177][178][179]. Bei der heterogenen Katalyse werden zwei Fälle unterschieden: zum einen sind an der Halbleiteroberfläche beide Reaktionskomponenten adsorbiert, zum anderen ist nur eine adsorbiert.…”