A comparative study for the removal of As(III) and As(V) by activated alumina

Contamination of arsenic in drinking water is a severe health risk indifferent parts of the world. In the present study effectiveness of activated alumina (AA) was examined for the adsorption of arsenite and arsenate ions from water. Batch experiments with temperature and agitation control was employed to determine the adsorption capacity and adsorption kinetics for arsenite and arsenate removal. Removal of both As(III) and As(V) was found to be strongly dependent on initial pH of water. Effects of contact time, temperature, initial concentration of adsorbent dose and adsorbate concentration were studied to establish optimum conditions. The present investigation revealed that arsenate ions adsorb well on activated alumina at pH less then pH(ZPC) (8.2) and maximum removal (98.6%) was achieved at pH 5.8 from water. Compared to As(V), As(III) ions have high affinity towards activated alumina at pH 7.6. The experimental data for adsorption of both As(III) and As(V) fitted well to the Freundlich and Langmuir adsorption isotherm and adsorption was favorable. Column experiments revealed that the breakthrough performance strongly depends on bed height and feed flow rate. By taking chemistry of water into consideration, this process can be used effectively for the removal of arsenic species.