LIVE AND DEAD SPIRULINA SP TO REMOVE ARSENIC (V) FROM WATER

Arsenic (As)-contaminated water is a grave health hazard and its removal from water poses a great challenge. Conventional methods are associated with many shortcomings. Biosorption of arsenic using blue-green algae is an interesting alternative to conventional methods. In this article, the results of the biosorption of As(V) as AsO4- 3 by live and dead Spirulina sp. are reported. The sorption of arsenic could be explained satisfactorily both by the Freundlich and the Langmuir isotherms. The maximum sorption capacities of live and dead Spirulina were estimated to be 525 and 402mg/g, respectively. These values are high in comparison with those reported for other arsenic sorbents. The sorption kinetics of arsenic by both live and dead Spirulina sp. could be well modeled by Lagergrens pseudosecond order-rate equation. Infrared spectra have been employed to understand how Spirulina sp. binds with arsenate. Scanning electron micrography and fluorescent microscopic images are used to discuss the extent of uptake. Preferential uptake of Cu(II), Ni(II), Cd(II), and AsO4-3 by live Spirulina sp. was investigated and explained with the help of rate constants for sorption.