Nitrate removal from aqueous solutions by ZnO nanoparticles and chitosan-polystyrene-Zn nanocomposite: Kinetic, isotherm, batch and fixed-bed studies.

Chitosan-polystyrene-Zn nanocomposite was synthesized through precipitation procedure and well characterized by analytical instruments such as Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. After characterizations, the nanocomposite was applied as an adsorbent for removal of nitrate ions from aqueous solutions. The study parameters influencing batch adsorption show that 0.5g of chitosan-polystyrene-Zn nanocomposite removed 90% of the nitrate ions (initial concentration 10mg/L) from 25mL of water at pH=3 after 30min while, in fixed-bed column technique, and at a similar condition, it removed 82.5% of nitrate. On the other hand, ZnO nanoparticles after activation by HCl solution applied for removal of nitrate contamination at the same condition which was used for chitosan-polystyrene-Zn nanocomposite. But ZnO nanoparticles removed all nitrate in the polluted solution in both techniques. The Elovich and the Langmuir models successfully exhibited the experimental data kinetic and isotherm for the adsorption processes.