Adsorption of quinoline from aqueous solutions by some clays and oxides

Abstract The adsorption isotherms of quinoline from aqueous olutions by some clays and oxides varied from the S type for silica to a form somewhat similar to the Langmuir type for montmorillonite and silica-alumina. The adsorption reaction reached equilibrium in about 2 hr and was irreversible. X-ray powder diffraction studies howed that a single layer of molecules i adsorbed on montmorillonite and that the molecules lie either flat or in an upright position depending on surface coverage. The adsorption showed high sensitivity owards pH, attaining a maximum at pH 6. The decrease below pH 6 was due to competition with protons as well as to problems inherent in surface packing of positively charged quinoline molecules. The decrease above pH 6 is probably due to more exchangeable metallic ations on the surface leading to a favored sorption of water over organic molecules. Key Words---Adsorption, Montmorillonite, pH, Quinoline, Silica-alumina, X-ray powder diffraction