Application of chitosan-citric acid nanoparticles for removal of chromium (VI).

In the present study, CS-CA nanoparticle was prepared for forming a new amide linkage, by grafting the amino groups of CS in the presence of carboxylic groups of CA that acts as cross-linking agent. The as-prepared CS-CA nanoparticle samples were characterized by use of dynamic light scattering (DLS), scanning electron microscopy (SEM), Fourier-transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques, which showed that the cross-linking agent preserved during the chemical modifications. The adsorption capacity of the CS-CA nanoparticles for the removal of Cr (VI) in aqueous solution was studied. The adsorption equilibrium data taken at the optimized condition, i.e., 25 °C and pH of 3, were analyzed with the Langmuir, Freundlich and Redlich-Peterson isotherm models. The kinetics of Cr (VI) adsorption on CS-CA nanoparticles obtained at different initial concentrations were also analyzed using the pseudo-second-order model.