Adsorption of benzene derivatives on allophane

The adsorption properties of benzene derivatives from water on allophane, extracted from soil, have been investigated by UV and FTIR spectroscopic measurements. Allophane adsorbs benzoic acid, phthalic acid, benzaldehyde, ethyl benzoate, and diethyl phthalate. Benzoic acid, phthalic acid, and benzaldehyde formed carboxylate anions on the positive sites of the hydrated alumina surface of allophane. In the case of adsorption from an acidic solution (pH 2), a small amount of a neutral species of benzoic acid was detected on the allophane. Ethyl benzoate and diethyl phthalate were adsorbed by an interaction between their carbonyl groups and the hydroxyl groups of the allophane. It was confirmed that allophane has an adsorption ability for the benzene derivatives that are not only ionic but also polar molecules. Allophane was found to be available as an absorbent for use in water purification by a simple procedure.