title: Adsorption of phosphate ions from an aqueous solution by calcined nickel-cobalt binary hydroxide.
abstract: Different molar ratios of a Ni/Co binary hydroxide (NiCo82, NiCo91, and Ni100) were prepared and calcined at 270 °C (NiCo82-270, NiCo91-270, and Ni100-270). The properties of the adsorbents and the amount of adsorbed phosphate ions were evaluated. The adsorbents calcined at 270 °C had a nickel oxide structure. The amount of adsorbed phosphate ions, the amount of hydroxyl groups, and the specific surface area of the calcined adsorbents at 270 °C were greater than those of the uncalcined adsorbents. The amount of adsorbed phosphate ions was related to the amount of hydroxyl groups and the specific surface area; the correlation coefficients were 0.966 and 0.953, respectively. The adsorption isotherm data for NiCo91 and NiCo91-270 were fit to both the Freundlich and Langmuir equations. The amount of adsorbed phosphate ions increased with increasing temperature. The experimental data fit the pseudo-second-order model better than the pseudo-first-order model. A neutral pH was optimal for phosphate ion adsorption. In addition, the phosphate ions that were adsorbed onto NiCo91-270 could be recovered using sodium hydroxide, and the adsorbent was useful for the repetitive adsorption/desorption of phosphate ions. Collectively, these results suggest that NiCo91-270 is prospectively useful for the adsorption of phosphate ions from aqueous solutions.
authors.affiliation: Faculty of Pharmacy, Kinki University, 3-4-1 Kowakae, Higashi-Osaka, Osaka 577-8502, Japan E-mail: kawasaki@phar.kindai.ac.jp.
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Ogata
authors.affiliation: Faculty of Pharmacy, Kinki University, 3-4-1 Kowakae, Higashi-Osaka, Osaka 577-8502, Japan E-mail: kawasaki@phar.kindai.ac.jp.
authors.forename: Erimi
authors.initials: E
authors.lastname: Ueta
authors.affiliation: Kansai Catalyst Co., Ltd, 1-3-13, Kashiwagi-cho, Sakai-ku, Sakai, Osaka 590-0837, Japan.
authors.forename: Megumu
authors.initials: M
authors.lastname: Toda
authors.affiliation: Kansai Catalyst Co., Ltd, 1-3-13, Kashiwagi-cho, Sakai-ku, Sakai, Osaka 590-0837, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Otani
authors.affiliation: Faculty of Pharmacy, Kinki University, 3-4-1 Kowakae, Higashi-Osaka, Osaka 577-8502, Japan E-mail: kawasaki@phar.kindai.ac.jp; Antiaging Center, Kinki University, 3-4-1 Kowakae, Higashi-Osaka, Osaka 577-8502, Japan.
authors.forename: Naohito
authors.initials: N
authors.lastname: Kawasaki
mesh_terms: D000327:Adsorption; D000536:Aluminum Hydroxide / Q000737:chemistry; D003035:Cobalt / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides / Q000737:chemistry*; D007700:Kinetics; D009532:Nickel / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry*; D012996:Solutions; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D006878:Hydroxides; D010710:Phosphates; D012996:Solutions; D014867:Water; D003035:Cobalt; D000536:Aluminum Hydroxide; D009532:Nickel