Chitosan was extracted and characterized using several analyses. The produced chitosan was reacted by
glycine and chloroacetic acid. Chemical structures of biosorbents were confirmed. Adsorption
efficiencies of the two biosorbents in neutral and alkaline medium at 25 8C were determined using
atomic absorption spectroscopic analysis. Adsorption capacity ofmodified biosorbents toward Cu(II) and
Co(II) ions was determined and compared to virgin chitosan. The biosorbents showed lower adsorption
efficiency toward copper and cobalt ions compared to virgin biosorbent. Furthermore, adsorption
capacity of glycine–chitosan was higher than chloroacetic acid–chitosan biosorbents, which attributed
to chelating of amino groups than chloro-substituted polymer. Thermodynamic studies showed the
spontaneous behavior of the adsorption process of metal ions under the studied conditions. Entropy
changes indicate that the adsorption of the metal ions are endothermic process, and lower values of DS8
indicate the affinity toward metal ions by the biosorbents at different degrees depending on their
chemical structures.