Photodegradation of glyphosate in water by UV/H2O2 process.

CRISTINA S. ZALAZAR; AGUSTINA MANASSERO; ANTONIO NEGRO; RODOLFO J. BRANDI; ALBERTO E. CASSANO

Berlin

Conferencia; 5th International Conference Oxidation Technologies for Water and Wastewater Treatment; 2009

Glyphosate is an organophosphate herbicide, which is the most widely used in the world. In Argentina, over 13 million ha of arable land are dedicated to the production of transgenic, glyphosate-resistant (GR) soy. This production has been accompanied by an increase in the use of glyphosate (over 60 million L between 1998 and 1999). The United Nations estimates that less than 1 % of used pesticides in agriculture actually reach the crops. The rest ends up contaminating the soil, the air and, mainly, the water. Due to the lack of availability of onsite treatment technologies, only a small amount of this waste is currently treated. The combination of hydrogen peroxide and UV radiation seems to be a suitable option to decrease glyphosate concentration to acceptable limits. In this work the effects of initial pH, hydrogen peroxide initial concentration, and incident radiation in the glyphosate degradation were studied. The experimental device employed was a cylinder irradiated with a tubular, germicidal lamp. The small bath reactor was part of a recycle. The results have shown that the best conditions for degradation are: pH 7-10 and hydrogen peroxide concentration of 2.20-7.97 mM (75-271 mg/L). In addition, the identification of same intermediates was possible and a degradation path is suggested.