Synthesis of mesoporous NiO nanoparticles and their application in the adsorption of Cr(VI)

• Preparation mesoporous NiO nanoparticles by chemical precipitation method.
• Adsorption of Cr(VI) onto mesoporous NiO.
• Detailed adsorbent characterization and adsorption studies.

Mesoporous NiO nanoparticles were synthesized by chemical precipitation method, and they were characterized by various techniques. Average obtained nanoparticle size was about 15 nm by TEM technique, which has good consistency with the crystalline size calculated from XRD pattern. Morphology and purity of these nanoparticles were studied by FE-SEM and EDX techniques, respectively. Nitrogen physisorption and SEM image verified that the synthesized NiO nanoparticles possessed mesoporous structure. Specific surface area of these nanoparticles was calculated as 71.09 m2 g−1 by BET method. The results indicate that mesoporous NiO is efficient adsorbent for the removal of Cr(VI) from aqueous solutions. The effect of parameters such as Cr(VI) initial concentration, dosage of adsorbent, pH and temperature were investigated in the adsorption capacity of Cr(VI) from aqueous solutions onto mesoporous NiO. The equilibrium data were analyzed by various isotherm and kinetic models. The results showed that adsorption isotherm and kinetics in this process follow sips isotherm and pseudo-second-order kinetic, respectively.