Photolysis of atrazine in aqueous solution: role of process variables and reactive oxygen species.
Photochemical advanced oxidation processes have been considered for the treatment of water and wastewater containing the herbicide atrazine (ATZ), a possible human carcinogen and endocrine disruptor. In this study, we investigated the effects of the photon emission rate and initial concentration on ATZ photolysis at 254 nm, an issue not usually detailed in literature. Moreover, the role of reactive oxygen species (ROS) is discussed. Photon emission rates in the range 0.87 × 10(18)-3.6 × 10(18) photons L(-1) s(-1) and [ATZ]0 = 5 and 20 mg L(-1) were used. The results showed more than 65 % of ATZ removal after 30 min. ATZ photolysis followed apparent first-order kinetics with k values and percent removals decreasing with increasing herbicide initial concentration. A fivefold linear increase in specific degradation rate constants with photon emission rate was observed. Also, regardless the presence of persistent degradation products, toxicity was efficiently removed after 60-min exposure to UV radiation. Experiments confirmed a noticeable contribution of singlet oxygen and radical species to atrazine degradation during photolysis. These results may help understand the behavior of atrazine in different UV-driven photochemical degradation treatment processes.
Chemical Engineering Department, University of São Paulo, Avenida Prof. Luciano Gualberto, tr. 3, 380, São Paulo, Brazil, marpradosilva@usp.br.
Marcela Prado
MP
Silva
Ana Paula dos Santos
AP
Batista
Sueli Ivone
SI
Borrely
Vanessa Honda Ogihara
VH
Silva
Antonio Carlos Silva Costa
AC
Teixeira
D001280:Atrazine / Q000737:chemistry*; D052244:Endocrine Disruptors; D006540:Herbicides / Q000737:chemistry*; D007700:Kinetics; D010084:Oxidation-Reduction; D010782:Photolysis; D017382:Reactive Oxygen Species / Q000737:chemistry*; D014466:Ultraviolet Rays; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*
D052244:Endocrine Disruptors; D006540:Herbicides; D017382:Reactive Oxygen Species; D014874:Water Pollutants, Chemical; D014867:Water; D001280:Atrazine