Preparation of alumina-iron oxide compounds by gel evaporation method and its simultaneous uptake properties for Ni2+, NH4+ and H2PO4-.
Fe(2)O(3)/Al(2)O(3) powders with a range of Fe/Al compositions were prepared by a gel evaporation method to investigate the effect of alumina on the product phases, magnetic properties and simultaneous adsorption of Ni(2+) (a model heavy metal cation), NH(4)(+) (a model eutrophication-related cation) and H(2)PO(4)(-) (a model harmful anion). Precursor gels were prepared by dissolving Fe(NO(3))(3).9H(2)O and Al(NO(3))(3).9H(2)O in ethylene glycol, evaporating to dryness, grinding and heating at 300-1000 degrees C for 5h. The crystalline products were gamma-Fe(2)O(3) (maghemite), formed at 300-600 degrees C, or alpha-Fe(2)O(3) (hematite) and AlFeO(3), formed >600 degrees C. The temperatures of the phase change from gamma-Fe(2)O(3) to alpha-Fe(2)O(3) increased with increasing alumina additions. The resulting lattice parameters suggest that Al(3+) is incorporated into these phases up to about 15 mol.% at 300 degrees C, falling to 11 mol.% in the gamma-Fe(2)O(3) formed at 600 degrees C. The alpha-Fe(2)O(3) formed at 700 degrees C contained 6 mol.% Al, increasing to 14 mol.% at 1000 degrees C. The magnetic properties of the samples were measured using a vibrating sample magnetometer. The saturation magnetization values of the gamma-Fe(2)O(3)-containing samples increased with the addition of alumina to a maximum value of 61emu/g in the sample containing 95 mol.% Fe(2)O(3) heated at 400 degrees C. The simultaneous adsorption of Ni(2+), NH(4)(+) and H(2)PO(4)(-) from water was investigated by a batch method. The highest adsorption values were found for the sample containing 80 mol.% Fe(2)O(3) heated at 600 degrees C, which contained both gamma-Fe(2)O(3) and alpha-Fe(2)O(3). It was therefore concluded that the addition of alumina to iron oxide affects the crystalline phases and phase changes, and enhances the simultaneous cation and anion uptake ability of the materials.
Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, O-okayama, Meguro, Tokyo 152-8552, Japan.
Fahmida
F
Gulshan
Yoshikazu
Y
Kameshima
Akira
A
Nakajima
Kiyoshi
K
Okada
D000327:Adsorption; D000537:Aluminum Oxide / Q000737:chemistry*; D000641:Ammonia / Q000302:isolation & purification*; D003460:Crystallization; D005290:Ferric Compounds / Q000737:chemistry*; D005782:Gels; D007477:Ions; D008280:Magnetics; D009532:Nickel / Q000302:isolation & purification*; D044367:Phase Transition; D010756:Phosphoric Acids / Q000302:isolation & purification*; D011208:Powders
D005290:Ferric Compounds; D005782:Gels; D007477:Ions; D010756:Phosphoric Acids; D011208:Powders; C000499:ferric oxide; D000641:Ammonia; D009532:Nickel; C030242:phosphoric acid; D000537:Aluminum Oxide