Jornal de Ciência e Tecnologia de Membranas

Abstrato

Effect of Incandescent and Fluorescence Bulb on Pentachlorophenol and Di-methoate on Spinach Leaf Surface

Antony Kinyua*, James Kamau Mbugua, Gabriel A Waswa , Joyce GN Kithure

Photo-degradation of pentachlorophenol and Di-methoate on spinach leaf surface by incandescent and a fluorescence bulb was investigated. The study involved, spraying the standard pesticide solutions on 5 cm-by-5 cm spinach leaf obtained from Negara market before exposing to 40 W, 60 W, 75 W and 100 W incandescent bulbs and 9 W, 11 W, 15 W and 20 W fluorescence tube for 10, 20, 30, 60 and 120 minutes. The remaining residues level after exposure was determined by Shimadzu UV-Visible spectrophotometer at 322 nm and 229 nm for Pentachlorophenol and Di-methoate respectively.

The results obtained indicate that the photo-degradation of pesticide residue depends on light intensity, temperature, pesticide molecular structure and time of exposure. The rate constant ranged from 0.0091 to 0.0116 for Di-methoate and 0.046 to 0.069 for pentachlorophenol. The rate of degradation was highest during the first 8 minutes of exposure platooning after 20 minutes. The degradation was highest in incandescent bulbs. This explained by the fact that these bulbs author emit both light and heat. It was highest in 100 W due to the high number of photons responsible for chemical reaction. The residues breakdown followed 1st order kinetics.