Synthesis of strontium hydroxyapatite embedding ferroferric oxide nano-composite and its application in Pb~(2+) adsorption

摘要

A method of co-precipitation was used to synthesize a novel magnetic nano-composite strontium hydroxyapa- tite/ferroferric oxide (SrHAp/Fe _3 O _4) by embedding ferroferric oxide into strontium hydroxyapatite and this SrHAp/Fe _3 O _4 was utilized as adsorbent to remove Pb~(2+) from aqueous solutions. The morphology features at the micro level of the obtained adsorbent were characterized by scanning electron microscopy (SEM), transmis-sion electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface area and Fourier transform infrared (FTIR). The maximal immobilization capacity of Pb~(2+) reached to 1249 mg/g at the optimum adsorption condi-tions (dosage of 0.2 mg/mL, contact time for 20 min, pH at 4.5 and temperature at 25 ℃). Adsorption of Pb~(2+) onto SrHAp/Fe _3 O _4 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 Lang-muir isotherms. The thermodynamic parameters (ΔG b 0, ΔS = 21.8215 J/mol/K, ΔH = 0.1789 kJ/mol) indicated that adsorption process was a spontaneously endothermic reaction. Furthermore, the adsorbent, SrHAp/Fe _3 O _4 was good in terms of anti-interference through the interference of coexistence metal cation experiment.