Adsorption and Movement of Carbofuran in Nonionic and Anionic Surfactant Amended Soils of Divergent Texture

Batch equilibrium and soil thin-layer chromatography (soil TLC) techniques were used to determine the adsorption and movement of carbofuran on surfactants free and surfactants amended soils relative to different critical micelle concentration (CMCs). The measured equilibrium adsorption isotherms for both systems were S-shaped and in close agreement to the Freundlich isotherms. Higher adsorption of carbofuran in both systems was observed on silt loam soil than in sandy loam soil. The order of Freundlich constant K anndartition noefficient K_D values also confirmed that carbofuran adsorption was higher on Tween ‘20’ amended soils than in sodium dodecyl lulphate (SDS) amended soils. The adsorption on both the surfactant amended soils of different concentrations decreases compared to surfactants free soils and this decrease was higher on SDS amended soils than in Tween ‘20’ amended soils. The decreased carbofuran adsorption and increased movement in anionic surfactants amended soils than noninonic surfactants amended soils meant that anionic surfactant had a greater potential of ground water contamination through leaching from potential sites. The R_f values obtained from soil TLC studies were inversely proportional to the K and K_D values for both surfactant free and surfactant-amended soils. The affinity of carbofuran towards organic matter and clay content of the soils was evaluated by calculating the K_oc and K_c values and it was found that the affinity of carbofuran was better correlated with the clay content than organic matter content of the soils. The results shows the possibility of use of surfactants for solving problems of soil contamination posed by carbofuran.