Preparation of a novel PAN–zeolite nanocomposite for removal of Cs+ and Sr2+ from aqueous solutions: Kinetic, equilibrium, and thermodynamic studies

Abstract

In this research a novel nanocomposite adsorbent consisting of nanocrystalline zeolite A and polyacrylonitrile (PAN) was prepared. Nanocrystalline zeolite A was synthesized by a new method using tetra methyl ammonium hydroxide and tetra methyl ammonium bromide as templating agents. The sample was characterized by X-ray diffraction, X-ray fluorescence spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and differential thermogravimetric technique. The nanocomposite was evaluated for removal of Cs+ and Sr2+ from aqueous solutions. The effect of different variables such as pH, initial concentration, contact time, and temperature was studied and optimized. The kinetic studies showed that the process was quite rapid and 90% of equilibrium capacity was achieved within 30min. The process followed the pseudo-second-order kinetic model with k2 values of 0.1912 and 0.1839gmmol−1min−1 for Cs+ and Sr2+ respectively. Positive ΔH° and negative ΔG° were indicative of the endothermic and spontaneous nature of Cs+ and Sr2+ removal. The Langmuir, Freundlich, and Dubinin–Radushkviech (D–R) isotherm models were also used to describe the equilibrium data.