A density functional theory study of arsenic immobilization by the Al(III)-modified zeolite clinoptilolite

Joel B Awuah; Nelson Y Dzade; Richard Tia; Evans Adei; Bright Kwakye-Awuah; C Richard A Catlow; Nora H de Leeuw

doi:10.1039/c6cp00190d

A density functional theory study of arsenic immobilization by the Al(III)-modified zeolite clinoptilolite

Phys Chem Chem Phys. 2016 Apr 28;18(16):11297-305. doi: 10.1039/c6cp00190d.

Authors

Joel B Awuah¹, Nelson Y Dzade², Richard Tia³, Evans Adei³, Bright Kwakye-Awuah⁴, C Richard A Catlow⁵, Nora H de Leeuw⁶

Affiliations

¹ Department of Physics, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
² Department of Earth Sciences, Utrecht University, Princetonplein 9, Utrecht, 3584 CC, The Netherlands. N.Y.Dzade@uu.nl N.H.Deleeuw@uu.nl.
³ Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
⁴ Department of Physics, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana and Department of Chemistry, University College London, 20 Gordon Street, WC1H 0AJ, UK.
⁵ School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.
⁶ Department of Earth Sciences, Utrecht University, Princetonplein 9, Utrecht, 3584 CC, The Netherlands. N.Y.Dzade@uu.nl N.H.Deleeuw@uu.nl and Department of Chemistry, University College London, 20 Gordon Street, WC1H 0AJ, UK and School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.

PMID: 27052997
DOI: 10.1039/c6cp00190d

Abstract

We present density functional theory calculations of the adsorption of arsenic acid (AsO(OH)3) and arsenous acid (As(OH)3) on the Al(III)-modified natural zeolite clinoptilolite under anhydrous and hydrated conditions. From our calculated adsorption energies, we show that adsorption of both arsenic species is favorable (associative and exothermic) under anhydrous conditions. When the zeolite is hydrated, adsorption is less favourable, with the water molecules causing dissociation of the arsenic complexes, although exothermic adsorption is still observed for some sites. The strength of interaction of the arsenic complexes is shown to depend sensitively on the Si/Al ratio in the Al(III)-modified clinoptilolite, which decreases as the Si/Al ratio increases. The calculated large adsorption energies indicate the potential of Al(iii)-modified clinoptilolite for arsenic immobilization.

Publication types

Research Support, Non-U.S. Gov't