Sorption of Bi3+ from acidic solutions using nano-hydroxyapatite extracted from Persian corals
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Nano-crystallite hydroxyapatite (nano-HAp) synthesized from Persian corals was used for removing Bi3+ from acidic aqueous solutions. The effects of initial concentration, adsorbent dosage, contact time and temperature were studied in batch experiments. The sorption of Bi3+ by nano-HAp increased as the initial concentration of bismuth ion increased in the medium. The pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models were applied to study the kinetics of the sorption processes. The pseudo-second-order kinetic model provided the best correlation (R 2 > 0.999) of the used experimental data compared to the pseudo-first-order and intraparticle diffusion kinetic models. Various thermodynamic parameters, such as \( \Updelta G^\circ \), \( \Updelta H^\circ \) and \( \Updelta S^\circ \) were calculated. Thermodynamics of Bi3+ cation sorption onto nano-HAp system pointed at spontaneous and endothermic nature of the process. The maximum Bi3+ adsorbed was found to be 3,333.33 mg g−1. It was found that the sorption of Bi3+ on nano-HAp correlated well (R 2 = 0.979) with the Langmuir equation as compared to Freundlich and Dubinin–Kaganer–Radushkevich (D-K-R) isotherm equations under the concentration range studied. This study indicated that nano-HAp extracted from Persian corals could be used as an efficient adsorbent for removal of Bi3+ from acidic aqueous solution.
KeywordsSorption Bi3+ Nano-hydroxyapatite Thermodynamic Kinetic
This research was completely supported by Materials and Energy Research Center (MERC) under the project No. 371390051 for which the authors are grateful.