Adsorption studies of nonionic surfactants on charcoal and alumina in aromatic solvents

Abstract Adsorptions of Tween 80 and Span 80 (nonionic) surfactants from benzene, toluene, and xylene solutions onto activated charcoal (AC) and neutral alumina (AN) are studied at 30°C. A Langmuir fit has been found. The molecular cross-sectional surface area of the adsorbed surfactant molecules under solvated and unsolvated conditions are determined in different solvents on AC and AN. The results are rationalized, invoking horizontal adsorptions and solvent–solvation differences. The low free energy changes of adsorptions found are indicative of physisorption.