Fabrication of magnetic particles reinforced nano- hydroxyapatite/gelatin composite for selective Cr(ⅵ) removal from water

摘要

The presence of chromium ion in drinking water has been proven to be toxic and carcinogenic. Hence, an attempt has been made to synthesize magnetic Fe3O4 fabricated with nano-hydroxyapatite (n-HAp)/gelatin (Gel) biocomposite by both in situ precipitation (in situ) and hydrothermal (hydro) methods. The hydrothermal-assisted Fe3O4@n-HApGel biocomposite achieved enhanced sorption capacity (SC) compare to the in situ precipitation method. The physico-chemical properties of the as-synthesized adsorbents were thoroughly characterized using various advanced instrumental techniques, namely, FTIR, XRD, SEM, EDAX, TEM and BET surface area analysis. Chromium adsorption mechanism of hydrothermal-assisted Fe3O4@n-HApGel composite was described by electrostatic attraction with surface complexation and reduction. The chromium adsorption behaviour of hydrothermal-assisted Fe3O4@n-HApGel biocomposite was interpreted using Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms. The thermodynamic experimental data of Fe3O4@n-HApGel biocomposite indicates that the chromium sorption process is endothermic and spontaneous in nature. Fe3O4@n-HApGel composite can be easily recycled for more than 5 cycles using NaOH eluent. In addition, the magnetic biocomposite is also suitable for treating chromium polluted ground water.