Preparation of chitosan from the shrimp shells and its application for pre-concentration of uranium after cross-linking with epichlorohydrin

Chitosan (CTS) was first prepared by proper treatment of shrimp shells and the cross-linked chitosan (CCTS) was then synthesized by its reaction with epichlorohydrin (ECH) under alkaline conditions. Adsorption of uranium from aqueous nitrate solution onto CCTS was investigated batch wise. The adsorption isotherm and the adsorption kinetic as well as thermodynamic studies of this adsorption are carried out. The influence factors on uranium (VI) adsorption were optimized and were found to include an initial pH of 3 and a contact time of 120 min. The Langmuir adsorption model was then applied for the mathematical description of the obtained adsorption equilibrium and where its data greatly agree with that model and where the maximum adsorption capacity was estimated to be 903 mg/g. Adsorption kinetics data were also tested using pseudo-first-order and pseudo-second-order models and where the studied adsorption followed the latter. In addition, determination of the thermodynamic parameters (ΔG°, ΔH° and ΔS°) using van’t Hoff equation has indicated that the prepared CCTS can conveniently be used for uranium adsorption from its aqueous solution.