Uranium removal by chitosan impregnated with magnetite nanoparticles: Adsorption and desorption

A magnetic biosorbent composed of nanoparticles of magnetite covered with chitosan, denominated magnetic chitosan, was prepared. The magnetic chitosan showed a magnetic response of intense attraction in the presence of a magnetic field without becoming magnet, a typical behaviour of superparamagnetic material. Its adsorption performance was evaluated by the adsorption isotherm models of Langmuir and Freundlich for uranium ions, and the desorption behaviour using carbonate and oxalate ions was investigated. The adsorption equilibrium data fitted well to the Langmuir model, being the maximum adsorption capacity equal 42 mg g-1. In the desorption studies, 94% of recovered UO 22+ with carbonate ion was verified under the conditions studied. The chitosan, available as a byproduct of marine food processing, is environmentally safe and can be a low cost adsorbent for U removal from wastewater. The magnetic chitosan as adsorbent of U to treat radioactive wastewater is a sustainable technology. © 2010 Inderscience Enterprises Ltd.