Synthesis of strontium hydroxyapatite embedding ferroferric oxide nano-composite and its application in Pb2+ adsorption

A method of co-precipitation was used to synthesize a novel magnetic nano-composite strontium hydroxyapatite/ferroferric oxide (SrHAp/Fe3O4) by embedding ferroferric oxide into strontium hydroxyapatite and this SrHAp/Fe3O4 was utilized as adsorbent to remove Pb2+ from aqueous solutions. The morphology features at the micro level of the obtained adsorbent were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface area and Fourier transform infrared (FTIR). The maximal immobilization capacity of Pb2+ reached to 1249 mg/g at the optimum adsorption conditions (dosage of 0.2 mg/mL, contact time for 20 min, pH at 4.5 and temperature at 25 degrees C). Adsorption of Pb2+ onto SrHAp/Fe3O4 agreed well with the pseudo-second order model (R-2 = 0.9997). For adsorption isotherms, the Freundlich isotherm was provided to be the best correlation (R-2 = 0.9862) compared to the Henry and Langmuir isotherms. The thermodynamic parameters (Delta G < 0, Delta S = 21.8215 J/mol/K, Delta K = 0.1789 kJ/mol) indicated that adsorption process was a spontaneously endothermic reaction. Furthermore, the adsorbent, SrHAp/Fe3O4 was good in terms of anti-interference through the interference of coexistence metal cation experiment. (C) 2014 Elsevier B.V. All rights reserved.