ADSORPTION ISOTHERMS OF SOME COMMERCIAL SURFACTANTS ONTO CLAY. COMPARISONS WITH SYNTHESIS SURFACTANT

Abstract

The adsorption of polyoxyethylene mono soya bean fatty acid [Soy (EO)_20,40 and ₈₀] and polyoxyethylene (80) monolinoleate [Li(EO)₈₀] onto Na-montmorillonite has been determined at 30°C. The adsorption isotherms of all the tested surfactants exhibit an L-shaped following the Langmuirian model. The experimental adsorption data are fitted to Langmuir adsorption equation, the maximum amount adsorbed, Γ_max, and the minimum area occupied per molecule, A_max at the pseudo-plateau have been calculated. Γ_max value increases with the increase in the number of ethylene oxide units following the order, Soy (EO)₂₀ < Soy (EO)₄₀ Soy (EO) ≃ Li (EO)₈₀. Both Soy (EO)₈₀ and Li (EO)₈₀ nearly show the same adsorption behavior.

Key words:

• Surfactant
• conductivity
• clay
• adsorption