Document Type : Original Article
Author
Department of Pesticide Chemistry and Technology, Faculty of Agriculture, Alexandria University, Aflaton St., 21545, El-Shatby, Alexandria, Egypt
Abstract
the adsorption-desorption isotherms of thiamethoxam in clay loam, clay, sandy loam, sandy clay loam, sand, and loamy sand soils at 25 and 50 ˚C were studied. The amount of thiamethoxam adsorbed and desorbed by soils was significantly influenced by the temperature. The average of adsorbed of thiamethoxam on soils were 13.129, 14.611, 12.305, 6.812, and 6.943 µg g soil-1 for clay loam, clay, sandy loam, sandy clay loam, and loamy sand soil, respectively. However, the adsorbed amount was reduced to 11.238, 10.450, 7.430, 5.578, and 6.832 µg g soil-1 for clay loam, clay, sandy loam, sandy clay loam, sand, and loamy sand soils as the temperature was decreased to 25˚C, except for sand soil. The value of Freundlich adsorption coefficient (KF) in adsorption for clay loam and sandy clay loam soil is greater at 25˚C than that at 50˚C and the opposite in clay, sandy loam, sand, and loamy sand soil. Freundlich model was the best fit for thiamethoxam adsorption and desorption on all soils. The adsorption and desorption of thiamethoxam in soils are spontaneous with a high affinity for thiamethoxam.
Keywords
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