title: Uptake properties of Ni2+ by nCaO.Al2O3.2SiO2 (n=1-4) prepared from solid-state reaction of kaolinite and calcite.
abstract: A series of nCaO.Al2O3.2SiO2 samples (n=1-4) were prepared by solid-state reaction of mechanochemically treated mixtures of kaolinite and calcite fired at 600-1000 degrees C for 24 h. All the samples were X-ray amorphous after firing at 600-800 degrees C but had crystallized by 900 degrees C. The main crystalline phases were anorthite (n=1), gehlenite (n=2 and 3) and larnite (n=4). The uptake of Ni2+ by nCaO.Al2O3.2SiO2 samples fired at 800 and 900 degrees C was investigated at room temperature using solutions with initial Ni2+ concentrations of 0.1-50 mmol/l. Amorphous samples (fired at 800 degrees C) showed a higher Ni2+ uptake capacity than crystalline samples (fired at 900 degrees C). Ni2+ uptake was found to increase with increasing of CaO content. Amorphous 4CaO.Al2O3.2SiO2 showed the highest Ni2+ uptake capacity (about 9 mmol/g). The Ni2+ uptake abilities of the present samples are higher than those of other materials reported in the literature. Since the sorbed Ni2+/released Ca2+ ratios of these samples are close to unity, ion replacement of Ni2+ for Ca2+ is thought to be the principal mechanism of Ni2+ uptake by the present samples.
authors.affiliation: Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, O-okayama, Meguro, Tokyo 152-8552, Japan.
authors.forename: Vinay Kumar
authors.initials: VK
authors.lastname: Jha
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Kameshima
authors.forename: Akira
authors.initials: A
authors.lastname: Nakajima
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Okada
authors.forename: Kenneth J D
authors.initials: KJ
authors.lastname: MacKenzie
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D002119:Calcium Carbonate / Q000737:chemistry*; D007616:Kaolin / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis; D014877:Water Pollution, Chemical / Q000517:prevention & control
chemical_list: D000538:Aluminum Silicates; D014874:Water Pollutants, Chemical; D007616:Kaolin; D009532:Nickel; D002119:Calcium Carbonate