The Degradation of Atrazine and Other Pesticides by Photolysis

Abstract

Groundwaters from chalk aquifers which are used as a supply for drinking water are often contaminated with pesticides ‐ in particular, atrazine. This paper discusses the use of an industrial‐scale ultraviolet chamber to reduce the concentration of atrazine in a chalk‐derived water which is used for drinking water supply. The concentration of atrazine varied between 0.1 μg/l and 0.5 μg/l, and the raw water was spiked when necessary. Results for other pesticides contaminants are also presented.The efficiency of atrazine removal is dependent only on the energy input and is constant, regardless of the initial concentration. Hydrogen peroxide improves the efficiency of ultraviolet irradiation but requires high doses.

Photolytic Treatment of Atrazine‐Contaminated Water: Products, Kinetics, and Reactor Design

“…However, in low atrazine concentrations (<70 μg/L), such as those in contaminated river water, only a few products exist in detectable levels. Our observation was that hydroxyatrazine (retention time, 8.5 minutes) was the primary product in agreement with the literature ( Azenha et al, 2003 ; Bourgine, 1995 ; Hequet et al, 2001 ; Nick et al, 1992 ), and an unknown product (retention time, 10.5 minutes) was the secondary product (Figure 2). The hydroxyatrazine peak was identified by means of HPLC/MS, and its retention time matched with that of commercial standard hydroxyatrazine (99.2 μg/mL in methyl alchohol: acetone (98:2), AccuStandard Inc., New Haven, Connecticut).…”

“…For the design of a continuous‐flow photochemical reactor, the known design parameters include operating flowrate, V fr (dm 3 /min); water transmittance, T ; initial atrazine concentration, C °; and outlet atrazine concentration, C. The parameters to be determined are reactor volume, V (L); number, d , reflecting average distance (cm/cm); and UV output power, P (W). Although the UV dose (the applied energy per unit area) is often used for disinfections, for photochemical decomposition, under the condition of complete mixing, directly using the applied UVC power is appropriate and preferred for an industrial application ( Bourgine et al, 1995 ). Integrating , we obtain the following: then and shows that the atrazine outlet concentration is related to the atrazine initial concentration, water transmittance, applied UVC output power, and flowrate in the reactor.…”

“…Others ( Aaron and Oturan, 2001 ; Aguera and Fernandez‐Alba, 1998 ; Gong et al, 2001 ; Zeng et al, 2002 ) analyzed atrazine and its photochemical fate. Only Bourgine et al (1995) observed atrazine degradation in trial runs of an industrial‐scale UV chamber under irradiation of a medium‐pressure mercury lamp. Studies on atrazine photolysis are limited and have not correlated a reactor performance with its operating parameters, such as UV output and water qualities.…”

Reaction pathways and mechanisms of photodegradation of pesticides

“…Various photoproducts have been identified, wavelengths longer than 300 nm. In a subsequent paper, 22 including SH , S , SO , SO , CS , amines, hydrazines, these authors studied the photolysis of 2-fluoro-and, 2-2 8 2 4 2 bromo-4,6-bis(ethylamino)-s-triazine, 2-iodo-triazine anadiscussed [149]. The efficiency of atrazine removal delogues of atrazine, propazine and simazine and 2-azido-4-pended only on the UV radiation input.…”

A review on pesticide degradation from irrigation water and techno‐economic feasibility of treatment technologies

“…But in indirect type, pesticide molecules react with intermediates, radicals, and electron-hole pairs formed due to sunlight. The degradation of various pesticides by the photolytic method has been extensively reported in the literature (Table 2) (Assalin et al, 2010;Bourgine et al, 1995;Chelme-Ayala et al, 2010;Chiron et al, 1995;Moctezuma et al, 2007;Moza et al, 1998;Rering et al, 2017;Wong & Chu, 2003).…”