Chitosan/nanohydroxyapatite composites based on scallop shells (CP12, CP14 and CP21) were prepared with different chitosan: nanohydroxyapatite ratios (1:2, 1:4 and 2:1, respectively). Nanohydroxyapatite (P), chitosan(C) and their composites were characterized by means of TGA, XRD, N2 adsorption/desorption analysis, SEM, Zeta potential and FTIR. The BET surface area ranged between 189 and 512 m2/g. Static adsorption of Hg+2 was tested for the effect of adsorbent dosage, pH, time and initial Hg+2 concentrations indicating that maximum static adsorption capacity was confirmed by CP12 (111.6 mg/g). Static adsorption well fitted with Langmuir adsorption isotherm and Pseudo-second order kinetic models. CP12 was selected for dynamic adsorption of Hg+2 considering the effect of bed height, flow rate and the effect of Hg+2 concentrations. Maximum dynamic adsorption capacity was confirmed at bed height of 3 cm, 2.0 mL/min flow rate and 300 mg/L as Hg+2 concentration with breakthrough time (tb) and exhaustion time (te) of 9 and 21 h. Yoon-Nelson and Thomas models best described the experimental Hg+2 breakthrough curve model. After static adsorption, EDTA solution confirmed the maximum desorption efficiency. The validity of CP12 was tested through three cycles of column dynamic adsorption-desorption.

Department of Chemistry Faculty of Science University of Damanhour Damanhour Egypt; Central European Institute of Technology Institute of Physics of Materials Žižkova 22 CZ 61662 Brno Czech Republic

Institute of Organic Chemistry and Technology Faculty of Chemical Technology University of Pardubice Czech Republic

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