Degradation of amicarbazone herbicide by photochemical processes

Autor(es)

de Castro Peixoto, Andre Luis ^{[1, 2]} ; Silva Costa Teixeira, Antonio Carlos ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Chem Engn, BR-05508900 Sao Paulo - Brazil

^[2] Fed Inst Educ Sci & Technol Sao Paulo IFSP, BR-13360000 Capivari, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY; v. 275, p. 54-64, FEB 1 2014.
• Citações Web of Science: 15

Resumo

Amicarbazone is a triazolinone herbicide developed to replace atrazine in the world market. Several technologies have been studied aiming at removing pesticides from wastewater, seeking to study the degradation mechanisms involved and the degree of toxicity of the transformation products formed. In this context, our main goal was to study the degradation of amicarbazone in aqueous solution by direct photolysis, suggesting possible chemical structures for the transformation products according to a theoretical and fundamental approach. The effects of herbicide initial concentration, pH, dissolved oxygen and nitrate concentrations, the role of singlet oxygen, and the presence of propan-2-ol as a free radical scavenger in amicarbazone photodegradation are discussed for the first time. Among these variables, pH showed influence on the photochemical degradation pathway. For instance, the transformation product amicarbazole was obtained under mildly acidic conditions, while 4-amino-5-oxo-3-(propan-2-yl)-4,5dihydro-1H-1,2,4-triazole-1-carboxamide intermediate was found in both acidic and basic conditions. A primary degradation product formed as a result of deamination in acidic medium was found out. Concerning the effect of the variables involved in the process, the lowest AMZ half-life of 120 min was achieved under the following conditions: pH =3; {[}AMZ](0) = 50 mg L-1; 75W LP-Hg lamp. (C) 2013 Elsevier B.V.. All rights reserved. (AU)

• Processo FAPESP: 08/56430-5 - Degradacao do herbicida amicarbazona por fotolise direta e h202/uv em reator fotoquimico anular coaxial.
• Beneficiário: André Luís de Castro Peixoto
• Modalidade de apoio: Bolsas no Brasil - Doutorado