Adsorption - desorption behavior of metolachlor [ 2-chloro-N- (2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide)] which is nonionic herbicide, and 2,4-D (2,4- dichlorophenoxyacetic acid) as anionic herbicide have been studied, by performing batch equilibrium experiments on six agricultural soil samples which has different texture. The adsorption processes of metolachlor and 2, 4-D on the soil solid matrix exhibited moderate rate of accumulation with 20.30% and, 24.71 % respectively after 0.5h. Data revealed that the adsorption- desorption of metolachlor and 2, 4-D on the selected soil samples followed the first order rate law. Linear and Freundlich models were used to describe the adsorption- desorption of the two pesticides. Variation in adsorption affinities of the soils to the pesticides was observed, distribution coefficient Kd values for adsorption process varied between 1.882 - 3.025 mlg-1 and 2.123- 3.989 mlg-1 for metolachlor and 2,4-D respectively , and for desorption process varied between 4.222- 10.986 and 4.755- 14.54 mlg-1 for metolachlor and 2,4-D respectively. Freundlich coefficient KF for metolachlor and 2,4-D ranged between 0.105-0.312 and 0.119-0.355 mlg-1 for adsorption processes. The value Freundlich coefficient for desorption process KFdes ranged from 0.479 to 1.130 mlg-1 and 0.284 to 1.012 mlg-1 for metolachlor and 2,4-D respectively. Values of equilibrium constant Ko conducted by the ratio between the constant rate of adsorption to the constant rate of desorption, equilibrium constant for metolachlor and 2,4-D on selected soil samples were in the following from 1.345 to 1.572 and from 1.157 to 1.706 respectively. All desorption isotherms exhibited hysteresis. Higher desorption hystersis (for metolachlor and 2,4-D was less readily desorbed).

Author Name: Rounak M. Shariff

URL: View PDF

Keywords: Adsorption –desorption kinetics and isotherms, HPLC, Metolachlor, 2, 4-D.,IJSER

ISSN: 22295518

EISSN:

EOI/DOI:

Add Citation Views: 4658

---