Glyphosate Photodegradation. Stoichiometry, Kinetic and Catalytic Effects

MARÍA A. TRINELLI; CECILIA GISELA CANTERA; MARÍA MAR ARECO; MARÍA DOS SANTOS AFONSO

International Journal of Environment and Health

Inderscience

Año: 2020 vol. 9 p. 306 - 326

1743-4955

In the present article the photodegradation of glyphosate (PMG) in aqueous solution by the action of UV-light and the catalytic effect of copper and copper-alga Ulva lactuca on the photodegradation is studied. The photodegradation kinetic reaction of PMG can be described using a first-order kinetic model, with a mean rate constant of k = (0.04 ± 0.01) h-1 and a mean half-life (t1/2) = (17 ± 4) h. The quantum yield () obtained for the photochemical decomposition of PMG was (4.8 ± 0.1) x 10-4 mol Einstein-1, and the photodegradation by-products obtained were: acetate, aminomethylphosphonic acid (AMPA), phosphate, sarcosine and to a lesser extent nitrate. The photolytic process seems to be the main responsible for the herbicide degradation. The presence of copper in the reaction media increases 30 times the rate of PMG degradation, with respect to the photodegradation in the absence of the metal. The degradation efficiency of the ternary system PMG-Cu-alga is ≈ 8 times higher than the photolysis of PMG in aqueous solution, but is around 4 times lower than the degradation efficiency in the presence of Cu(II). The present work represents a new approach on the photodegradation of the herbicide glyphosate that can contribute to the development of new remediation technologies.