Highly Efficient Removal of Organic Dyes from Waste Water Using Hierarchical NiO Spheres with High Surface Area

A facile solvothermal method has been developed for large-scale preparation of uniform spheres of a nickel-ethylene glycol complex (Ni-EG complex) with a hierarchical nanostructure. The dispersibility and hierarchical structure of the Ni-EG particles can be tuned by varying the concentration of additives added. On the basis of experimental observations, a plausible mechanism has been proposed to understand the formation process of the Ni-EG complex spheres. Calcining these as-prepared Ni-EG complex spheres at 300 degrees C in air results in uniform porous NiO spheres with a high specific surface area of 222 m(2) g(-1). When served as the adsorbent for Congo red in water, the colloidal suspension of the as-prepared NiO hierarchical spheres exhibits a high adsorption capacity for the dye removal, suggesting their potential use in water treatment.