Title: Enhanced removal of Cr (VI) from aqueous solution by mesoporous activated carbons

Authors: Mingxia Fan; Shitang Tong; Charles Q. Jia

Addresses: Department of Chemical Engineering, Wuhan University of Science and Technology, 947 Heping Avenue, Wuhan, Hubei 430081, China; College of Chemistry and Chemical Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China ' Department of Chemical Engineering, Wuhan University of Science and Technology, 947 Heping Avenue, Wuhan, Hubei 430081, China ' Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, M5S 3E5, Toronto, Ontario, Canada

Abstract: The capability of mesoporous activated carbons (MACs) to adsorb Cr (VI) in aqueous solution was investigated. The MACs were prepared in the lab from upgraded coal tar pitch using the nano-sized imprinting method. Adsorption of Cr (VI) was found to be dependent on the solution pH. The adsorption kinetic data was found to fit well with a pseudo-second-order rate equation. Three adsorption isotherm models were used to analyse the equilibrium data. Removal of Cr (VI) increased with an increase in mesoporosity of MACs, highlighting the importance of mesoporosity in enhancing adsorption efficiency. The major surface oxygen groups were carboxylic, lactonic and hydroxyl. X-ray photoelectron spectroscopy analysis was employed to investigate the sorption mechanism. It was revealed that a portion of Cr (VI) was adsorbed via electrostatic interaction, while the rest was adsorbed in the reduced form (Cr (III)) which was most likely bound to surface oxygen groups on the MAC. [Received: July 17, 2013; Accepted: November 13, 2013]

Keywords: chromium removal; mesoporous activated carbons; MAC; coal tar pitch; adsorption; surface oxygen groups; X-ray photoelectron spectroscopy; XPS; aqueous solutions; Cr(VI); nanoimprinting; nanotechnology; isotherm modelling; sorption mechanisms.

DOI: 10.1504/IJOGCT.2014.066301

International Journal of Oil, Gas and Coal Technology, 2014 Vol.8 No.4, pp.489 - 499

Received: 19 Jul 2013
Accepted: 27 Dec 2013
Published online: 23 Dec 2014 *

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