Adsorption of Aqueous Solutions of Carboxylic Acids on Montmorillonite, Silicalite, H-ZSM-5 and their Na+- and Li+- Exchanged Forms

The adsorption of binary carboxylic acid-water solutions on montmorillonite clay, silicalite, H-ZSM-5 zeolites and Li-exchanged montmorillonite, Na- and Li-exchanged ZSM-5 has been studied. The purity, morphology and textural properties were characterized by XRD and SEM techniques. Liquid phase adsorption experiments were carried out at room temperature in screwed cap septum 14 mL round bottom vials. The mole fractions before and after adsorption were determined refractometrically. Montmorillonite clays swelled to jell-form in aqueous carboxylic acid solutions indicating no significant separation selectivity for water or carboxylic acid. The zeolites showed hydrophobicity in the order: silicalite H-ZSM-5 Na- ZSM-5 Li- ZSM-5. The uptake of carboxylic acid was found in the order: C2HsCOOH CH,COOH HCOOH. At higher concentration the adsorption of carboxylic acids decreased.