Removal of copper(II) using chitin/chitosan nano-hydroxyapatite composite.

Polymeric composites made up of nano-hydroxyapatite (n-HAp) with chitin and chitosan have been prepared and studied for the removal of Cu(II) ions from the aqueous solution. The sorption capacity (SC) of n-HAp, n-HAp/chitin (n-HApC) composite and n-HAp/chitosan (n-HApCs) composite were found to be 4.7, 5.4 and 6.2 mg/g respectively with a minimum contact time of 30 min. Batch adsorption studies were conducted to optimize various equilibrating conditions like contact time, pH and selectivity of metal ion. The sorbents were characterized by FTIR, TEM, XRD and SEM with EDAX analysis. The sorption process was explained with Freundlich and Langmuir isotherms respectively. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were calculated to understand the nature of sorption. A suitable mechanism for copper sorption was established and the selectivity of the metal ions for the composites was identified.