PHOTODEGRADATION OF CHLORPYRIFOS

MARÍA ALCIRA TRINELLI; MARÍA DOS SANTOS AFONSO

Montreal, Québec, Canadá

Taller; ACS Summer School on Green Chemistry; 2005

Green Chemistry Institute-American Chemical Society

Chlorpyrifos 0,0-diethyl 0-(3,5,6-trichloro-2-pyridyl) phosphorothioate) is an organophosphorus insecticide - acaricide - nematicide of wide. It is used without restrictions in the agriculture and at domestic level in Argentina. Among the natural processes of removal of Chlorpyrifos of water columns they are the hydrolysis, biodegradation, volatilization, photodegradaction and union to the silts. Due to the low solubility of Chlorpyrifos in water (2 ppm), methanol was used as solvent and then a mixture methanol-water was looked for that which allowed to obtain concentrations of the dissolved compound between 10-5 and 10-4 M. The samples are irradiated with fluorescent tubes as UV luminous source. Samples were measured spectrophotometricaly to determine the concentration of the still existing Chlorpyrifos. An exponential decline of the absorbance is observed in all the essays with the time. It was determined that it is first order with respect to the reagent. The values for the photofegradation rate constant were found.