Identification of intermediates, acute toxicity removal, and kinetics investigation to the Ametryn treatment by direct photolysis (UV 254 ), UV 254 /H 2 O 2 , Fenton, and photo-Fenton processes

• Published in: Environmental science and pollution research international Vol. 26; no. 5; p. 4348
• Main Authors: de Oliveira, Dirce Martins, Cavalcante, Rodrigo Pereira, da Silva, Lucas de Melo, Sans, Carme, Esplugas, Santiago, de Oliveira, Silvio Cesar, Junior, Amilcar Machulek
• Format: Journal Article
• Language: English
• Published: Germany 20.02.2019
• Subjects: Aliivibrio fischeri - drug effects; Equipment Design; Herbicides - chemistry; Herbicides - toxicity; Hydrogen Peroxide - chemistry; Iron - chemistry; Kinetics; Oxidation-Reduction; Photolysis; Toxicity Tests, Acute; Triazines - chemistry; Triazines - toxicity; Ultraviolet Rays; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - toxicity; Water Purification - instrumentation; Water Purification - methods; Acute ecotoxicity; Water treatment; Fenton; Biodegradability; Degradation mechanism; Kinetic constant; Herbicide; Hydroxyl radical
• ISSN: 1614-7499
• DOI: 10.1007/s11356-018-1342-6

This paper reports the degradation of 10 mg L Ametryn solution with different advanced oxidation processes and by ultraviolet (UV ) irradiation alone with the main objective of reducing acute toxicity and increase biodegradability. The investigated factors included Fe and H O concentrations. The effectiveness of the UV and UV /H O processes were investigated using a low-pressure mercury UV lamp (254 nm). Photo-Fenton process was explored using a blacklight blue lamp (BLB, λ = 365 nm). The UV irradiation process achieved complete degradation of Ametryn solution after 60 min. The degradation time of Ametryn was greatly improved by the addition of H O . It is worth pointing out that a high rate of Ametryn removal was attained even at low concentrations of H O . The kinetic constant of the reaction between Ametryn and HO for UV /H O was 3.53 × 10  L mol  s . The complete Ametryn degradation by the Fenton and photo-Fenton processes was observed following 10 min of reaction for various combinations of Fe and H O under investigation. Working with the highest concentration (150 mg L H O and 10 mg L Fe ), around 30 and 70% of TOC removal were reached within 120 min of treatment by Fenton and photo-Fenton processes, respectively. Although it did not obtain complete mineralization, the intermediates formed in the degradation processes were hydroxylated and did not promote acute toxicity of Vibrio fischeri. Furthermore, a substantial improvement of biodegradability was obtained for all studied processes.