Titanium Dioxide-Mediated Photcatalysed Degradation of Two Herbicide Derivatives Chloridazon and Metribuzin in Aqueous Suspensions

Abstract

The aim of this paper is to find out the optimal degradation condition for two potential environmental pollutants, chloridazon and metribuzin (herbicide derivatives), employing advanced oxidation process using TiO 2 photocatalyst in aqueous suspensions. The degradation/mineralization of the herbicide was monitored by measuring the change in pollutant concentration and depletion in TOC content as a function of time. A detailed degradation kinetics was studied under different conditions such as types of TiO 2 (anatase/anatase-rutile mixture), catalyst concentration, herbicide concentration, initial reaction pH, and in the presence of electron acceptors (hydrogen peroxide, ammonium persulphate, potassium persulphate) in addition to atmospheric oxygen. The photocatalyst, Degussa P25, was found to be more efficient catalyst for the degradation of both herbicides as compared with two other commercially available TiO 2 powders like Hombikat UV100 and PC500. Chloridazon (CHL) was found to degrade more efficiently under acidic condition, whereas metribuzin (MET) degraded faster under alkaline medium. All three electron acceptors tested in this study were found to enhance the degradation rate of both herbicides.

Kinetics of Degradation of Metribuzin in aqueous solution using Zero Valent Iron Nanoparticles

“…From these results, it is sufficient to conclude that the degradtion of metribuzin by nZVI NPs occurs better in an acidic medum than basic medium. This is in agreement with several studies [15][16][17], which have reported slow degradation of most pesticides using Fe 0 with the increasing pH value of the reaction medium.…”

Health effects of herbicides and its current removal strategies

“…In another study, two different photocatalysts which were TiO 2 /Al 2 O 3 /carbon nanotube nanocomposite and TiO 2 /Al 2 O 3 /graphene were utilized for photocatalytic degradation of metamifop where photodegradation percentage were 95% and above in the presence of UV light and 2 Lmin −1 of air [ 110 , 111 ]. Khan et al [ 112 ] found that TiO 2 can efficiently catalyzed the degradation and mineralization of herbicide derivatives chloridazon, and metribuzin in the presence of UV light. In another chemical treatment approach, acid-treated graphene (G-COOH) catalyst was combined with ozone-activated peroxymonosulfate, while in a different investigation, G-C 3 N 4 co-doped with phosphorus and kalium was used [ 113 ].…”