Amino acid functionalized magnetic nanoparticles for removal of Ni(II) from aqueous solution

In this study, asparagine functionalized magnetic nanoparticles (Fe3O4-Aspa) were prepared and characterized by fourier transform infrared spectroscopy, x-ray diffractometer, scanning electron microscopy, transmission electron microscopy, vibrational sampling magnetometer and pHzpc. The functionalized magnetic nanoparticles were applied for Ni(II) adsorption by batch adsorption technique under different variable factors such as temperature, pH, contact time, adsorbent dosage etc. The study indicates that the adsorption reaction has fast kinetics with applied pseudo-first-order, pseudo-second-order, intra-particle diffusion and Elovich model. The pseudo-second order model found to be best linear fit with experimental data of Ni(II) adsorption. The high correlation coefficient (R2) of 0.996, 0.998, 0.998 and 0.999 at 20, 40, 60 and 80 mg l−1 of aqueous solution reveal that the pseudo-second order model is suitable for Ni(II) ions adsorption. The effect of contact time on Ni(II) adsorption has described that solution equilibrium was achieved within 70 min at optimized pH 6. The experimental adsorption capacity values were applied to Langmuir and Freundlich isotherm model and found satisfactory result through best linear fitting of Langmuir isotherm model with high R2 of 0.999, 0.998 and 0.996 at 303, 308, and 313 K, respectively. The adsorption thermodynamics of parameters are found to be as 344.087 (kJ mol−1), 101.583 (kJ mol−1 K−1) and 1.640–1.172 (kJ mol−1), respectively at ΔH°, ΔSº and ΔGº which indicates that the adsorption process is spontaneous with exothermic nature. © 2016 Taiwan Institute of Chemical Engineers