Adsorption and Desorption Characteristics of Pretilachlor in Three Soils of Punjab

Abstract

The study delineates the investigation to determine the adsorption and desorption behaviour of Pretilachlor in three soils of Punjab with varying physicochemical characteristics using batch equilibration techniques. Kinetics of adsorption followed a pseudo-second-order model (R ²  > 0.99) and adsorption–desorption data fitted well to the Freundlich equation for the three soils. L-type isotherms were obtained for the adsorption process, which indicated high affinity between Pretilachlor and adsorption sites. The magnitude of logK _Fads values for the three soils ranged from 0.887–1.226 μg^1−1/n g⁻¹ mL^1/n and the order of adsorption was clay loam > sandy loam > loamy sand. Desorption of Pretilachlor was concentration dependent and in three desorption cycles ranged from 5.04 to 56.03 % in loamy sand, 3.14 to 23.12 % in sandy loam and 1.63 to 18.64 % in clay loam soil indicative of difficulty in the release of strongly adsorbed Pretilachlor. The removal of organic matter by hydrogen peroxide (H₂O₂) oxidation increased the adsorption of Pretilachlor in three Punjab soils. Pretilachlor desorption was hysteretic in the original as well as H₂O₂-treated soils. It could therefore be concluded that the adsorption was controlled by clay minerals and desorption of Pretilachlor in soils was controlled by the organic matter.

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