Adsorption of Chromium in Aqueous Solution by Using Zeolite A Prepared from Fly Ash

Abstract

Adsorption of Cr(III) and Cr(VI) in aqueous solution by the zeolite A from coal fly ash at various conditions has been carried out. Zeolite A was synthesized from fly ash through modified alkaline fusion hydrothermal process in a reactor stainless steel. Adsorption is carried out by direct contact between the adsorbent and adsorbate in an adsorption batch. Zeolite A from fly ash (ZA-FA) of 0.01 g was mixed with 20 mL both Cr(III) and Cr(VI) at various pH, contact time and initial concentration, in a flask Erlenmeyer 50 mL. The result showed that pH conditions of adsorption process, affect the adsorption ability of zeolite A to Cr(III) and Cr(VI) in aqueous solution. The adsorption of Cr(III) and Cr(VI) on zeolite A reached a maximum at pH 6 and time contact 120 minutes. The adsorption of Cr(III) on zeolite A increased from 3.4 mg/g at pH 3 and achieved a maximum adsorption of 42.67 mg/g at pH 6. At higher pH (7-8) the Cr(III) adsorption tends decreases. The adsorption ability of ZA-FA to Cr(III) is higher than that of Cr(VI) in aqueous solution. The Cr(III) adsorption process on ZA-FA follows the pseudo-order 2 kinetics model.