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

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.

The Effect of Si/Al Ratio on Local and Nanoscale Water Diffusion in H-Zsm-5: A Quasielastic Neutron Scattering and Molecular Dynamics Simulation Study

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Efficient Removal of Aqueous Manganese (II) Cations by Activated Opuntia Ficus Indica Powder: Adsorption Performance and Mechanism

“…11 Several physicochemical methods for manganese elimination such as aeration, filtration , ion exchange, and settling techniques have evolved in search of efficiency, affordability, and ease of use. [12][13][14] During these last few years, the adsorption technique has been considered one of the most preferred methods for removing traces of heavy metals from water and wastewater due to its high efficiency, ease of handling and the availability of various adsorbents. This physicochemical process is a sustainable cost-effective alternative process in the environment.…”

Rol de los planos cristalográficos {0001} y {0112} de la α-Fe₂O₃ en la remoción del arsénico

“…A partir de las energías y de las características geométricas de la adsorción calculadas, demostraron que ambas especies de As se adsorben favorablemente (asociativa y exotérmicamente) en condiciones anhidras, mientras que en la zeolita hidratada la adsorción es menos favorecida y disociativa. Las energías de adsorción obtenidas -mayores a −20 kJ/mol-dependen sensiblemente de la relación Si/Al, donde una relación baja de 1.7 demostró ser preferida para la zeolita en condiciones anhidras, pero la proporción de 5, demostró ser más favorable en condiciones de hidratación [66].…”