Experimental and Theoretical Study for The Photo degradation of Chlorpyrifos and Cypermethrin Insecticides on γ-Alumina Surface

R. Ali, Ramzi; Yousif,

	Experimental and Theoretical Study for The Photo degradation of Chlorpyrifos and Cypermethrin Insecticides on γ-Alumina Surface
Al-Mustansiriyah Journal of Science
Article 1, Volume 22, Issue 6, 2011, Pages 25-38
Authors
Ramzi R. Ali;
Abstract
In this research, experimental and theoretical study of the adsorption andphotodegradation of two insecticides (chlorpyrifos and cypermethrin) using the (UV) light and (gamma-alumina) as sensitizer.The photolysis of insecticides by using water and hexane as solvents at (pH=7-7.5) and (0.1g) of sensitizer were found increasethe rate of decomposition of both insecticides.The reactions of photodegradation of insecticides followed the first order reactions.It was observed that the increasing in reaction temperature led to increase the rate constant of the reaction (0.8×10-2-1.4×10-2)min-1 for chlorpyrifos and(1×10-2-1.6×10-2)min-1 for cypermethrin.Activation energy of degradation were calculated and found (22.971KJ. mol-1) for chlorpyrifos and (13.127 KJ. mol-1) which was relatively low, it explain the rapid reactions of insecticides. The values of heats of formation were calculated for both insecticides experimentally and theoretically using the hyper chem.8.0/semi-empirical(PM3) and the values were as follows (20.452 KJ. mol-1, (21.56)p KJ. mol-1) for chlorpyrifos and (10.608KJ.mol-1, (17.348)p KJ. mol-1) for cypermethrin, they showed apositive values which means that the decomposition processes of insecticides is an endothermic process. The electronic and vibrational spectra of both insecticides were identified experimentally and theoreticallyand found obvious changes.

Statistics Article View: 171 PDF Download: 118