Equilibrium, kinetics and thermodynamic studies for adsorption of As(III) on activated alumina

Contamination of drinking water due to arsenic is a severe health hazard problem. Most of the techniques developed for pentavalent arsenic [As(V)] species are not very effective for trivalent arsenic ions [As(III)] which are more toxic and mobile than arsenate ions. Present investigation aims to remove arsenite ions [As(III)] by activated alumina. Effect of adsorbent dose, solution pH, and contact time has been investigated. Kinetics reveal that uptake of As(III) ion is very rapid in the first 6h and equilibrium time is independent of initial As(III) concentration. The arsenite removal was strongly dependent on pH and temperature. Equilibrium studies show that As(III) ions have high affinity towards activated alumina at pH 7.6. Both Freundlich and Langmuir adsorption isotherms were well fit to the experimental data. Thermodynamic parameters depict the exothermic nature of adsorption and the process is spontaneous and favorable. The results suggest that activated alumina can be used effectively for the removal of A(III) ions. (C) 2003 Elsevier B.V. All rights reserved.