Sorption behavior of Zn (II) ions by low cost and biological natural hydroxyapatite/chitosancomposite from industrial waste water

摘要

Waste waters that contain heavy metal ions like Zn(II) are dangerous for the environment and can be removed by N-HAP/chitosan composite. Chitosan is one of the chitin derivatives that is the second most abundant polymer in nature and is found in the exoskeletons of insects and shellfish. Chitosan is derived from useless and inexpensive material. Natural hydroxyapatite (N-HAP) extracted from bone ash is a good substitution for commercial HAP and is lower in cost than commercial HAP, and has an easiermethod of preparation too. N-HAP and chitosan which are both made from biological materials, have the potential of sorption of heavy metal ions. In this paper the sorption capacity of N-HAP/chitosan composite is investigated to find the advantages of this composite material. Sorption of Zn(II) ions has been studied by equilibrium sorption methods like Langmuir and Freundlich. Furthermore, thermodynamic and kinetic sorption experiments are carried out in different pH and particle sizes. Results show thatthe maximum sorption of Zn(II) on N-HAP/chitosan particles is 1.692 mmol/g at pH 7.5 and 47.6 nm particle size, and better performance was obtained through a 47.6 nm particle size, and higher pH values. The most favorable and spontaneous characteristicof the sorption process was proved by thermodynamic and kinetic sorption experiments.