Carbaryl Adsorption on Calcium-Bentonite and Soils
1980
Aly, M. I. | Bakry, N. | Kishk, F. | El-Sebae, A. H.
Adsorption of carbaryl on Ca-bentonite, and two Egyptian soils, a Nile alluvial and a highly calcareous soil, was carried out at different temperatures. Carbaryl adsorption increased as the temperature decreases. Ca-bentonite exhibited the highest degree of adsorption followed by the Nile alluvial soil and the calcareous soil. The calculated partial molar heat of adsorption ΔH* for bentonite, alluvial and calcareous soils were −3.8, −0.924 and −10.282 kcal/mol, respectively, indicating that adsorption may be physical in nature. The ΔG* values of the three systems were −0.570, −0.118, and −0.346 kcal/mol, respectively, indicating that the adsorption reaction was spontaneous in all cases. The adsorption data followed the Freundlich adsorption equation. The entropy values for the adsorption of carbaryl by the three adsorbents were −15.0, −36.7, and −8.0 entropy units indicating that carbaryl adsorption is favored by the alluvial soil that contains the highest organic matter content.
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