Adsorption of Phosphate Ions from Aqueous Solution of Nickel Hydroxides Calcined at Different Temperatures

Abstract

Nickel hydroxide (Ni100) and nickel hydroxide, including cobalt (NiCo91), were calcined at different temperatures. These materials were investigated by analyzing data obtained from X-ray diffraction (XRD), scanning electron microscopy, specific surface area, thermogravimetric-differential thermal (TG-DTA) technique, and electron-probe microanalysis. The XRD and TG-DTA data obtained indicated that calcination at 250–270°C can promote the conversion of Ni(OH)₂ into NiO, and that cobalt hardly affected the structural changes of nickel hydroxide. The specific surface areas of Ni100 and NiCo91 were determined to be in the range 17.9–148.3 and 21.0–145.1 m²/g, respectively. The specific surface area increased suddenly at 260°C. The amount of phosphate adsorbed onto Ni100 and NiCo91 was measured to be in the range 29.2–44.7 and 29.7–54.0 mg/g, respectively. The amount adsorbed onto Ni100 or NiCo91 was greater than that onto another adsorbent previously reported. The correlation coefficient relationships between the specific surface areas of Ni100 and NiCo91 and the saturated amount of the adsorbed phosphate ions were found to be 0.935 and 0.960, respectively. These results suggested that adsorption of phosphate ions with Ni100 or NiCo91 is related to the specific surface area. Our study demonstrated that Ni100 and NiCo91 can be considered as promising materials for the adsorption of phosphate ions from aqueous solutions.[DOI: 10.1380/ejssnt.2014.404]