Granulation of cobalt-containing nickel hydroxide with polyethylene terephthalate and its phosphate ion adsorption capability

Abstract

In this study, nickel hydroxide containing cobalt as a co-precipitation hydroxide (NiCo91) was granulated with a binder (polyethylene terephthalate, PET) and characterized (scanning electron microscopy, specific surface area, amount of hydroxyl groups, and surface pH). In addition, the phosphate ion adsorption capability of the granulated adsorbent was evaluated by examining the effects of contact time and solution pH, analysis of adsorption isotherms, and a desorption study. It was confirmed that NiCo91 calcined at 270°C could be granulated using a PET binder. The specific surface area (32 m2/g) and hydroxyl group amount (0.19 mmol/g) of PET20S (20% binder content and < 500 μm particle diameter) were greater than those of other adsorbents. The amount of the adsorbed phosphate ions was greater for PET20S than that for other adsorbents, indicating that the adsorbent surface properties were related to the adsorption of phosphate ions. The phosphate ions adsorbed onto PET20S could be desorbed by different concentrations of sodium hydroxide, and at least three-fold increase in adsorption/ desorption onto PET20S could be obtained. The results show that PET20S is highly promising as a renewable adsorbent of phosphate ions from aqueous solutions.