Modelling the adsorption of fluoride onto activated alumina in the presence of other ions

Samrat, M V V N and Gandhi, K S and Rao, K K (2020) Modelling the adsorption of fluoride onto activated alumina in the presence of other ions. In: Journal of Environmental Chemical Engineering, 8 (5).

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Abstract

Removal of fluoride (F-) contamination in drinking water by adsorption has been studied experimentally, but often with synthetic solutions in the absence of other ions commonly present in a natural source. Selection of an adsorbent and design of adsorption columns for removal of F-from variety of feeds requires data on adsorption in the presence of other ionic species as well as models to predict the adsorption behaviour. A model is developed in this work which takes into account the speciation reactions that occur during adsorption onto activated alumina, and the presence of the ions H+, OH-, Na+, Cl-, and NO3- along with F-. The model accounts for the diffusional resistances in the multicomponent ionic system and the rates of adsorption reactions. Nernst-Planck equation is used to obtain the fluxes of the species. Data on adsorption are obtained using a differential bed adsorber. The data are used to determine the equilibrium constants and rate constants for the speciation reactions that appear in the model. The model was tested against independently determined batch adsorption data. A reasonable fit was obtained at low F-concentrations, except at short times. A significant discrepancy between predictions and data was observed at higher initial concentrations of F-, which is caused by an uncertainty in the amount of impurity present in the commercial adsorbent used. The model is general in nature and can be applied to any adsorbent with a charged interface. © 2020 Elsevier Ltd.

Item Type:	Journal Article
Publication:	Journal of Environmental Chemical Engineering
Publisher:	Elsevier Ltd
Additional Information:	The copyright for this article belongs to Elsevier Ltd.
Keywords:	Activated alumina; Aluminum oxide; Equilibrium constants; Fluorine compounds; Ions; Potable water; Rate constants, Adsorption behaviour; Adsorption columns; Adsorption reaction; Charged interfaces; Diffusional resistance; Initial concentration; Nernst-Planck equations; Synthetic solutions, Adsorption
Department/Centre:	Division of Mechanical Sciences > Chemical Engineering
Date Deposited:	23 Jul 2021 11:42
Last Modified:	23 Jul 2021 11:42
URI:	http://eprints.iisc.ac.in/id/eprint/66356

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