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The Effect of Adding Phosphate on the Size of Extremely Fine Needle‐like Lepidocrocite Particles Prepared by Oxidizing an Aqueous Suspension of Ferrous Hydroxide
Author(s) -
Mihara Naoki,
Kawasaki Hiroyuki,
Kumazawa Hidehiro,
Choi WooSik,
Kwak JungSup,
Choi HeeKyu
Publication year - 2002
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450800428
Subject(s) - lepidocrocite , ferrous , aqueous solution , oxidizing agent , aqueous suspension , hydroxide , suspension (topology) , particle size , chemistry , phosphate , oxygen , particle (ecology) , inorganic chemistry , reaction rate constant , materials science , nuclear chemistry , kinetics , goethite , adsorption , organic chemistry , mathematics , homotopy , pure mathematics , oceanography , physics , quantum mechanics , geology
Extremely fine particles of needle‐like lepidocrocite (γ‐FeOOH) were synthesized by the oxidation of aqueous suspensions of ferrous hydroxide using a bubble column with draft tube at a constant temperature of 30°C, and the effects of the reaction conditions or the oxidation rate were investigated in order to determine the parameters that control the particle size. When the concentration of oxygen in the feed stream was varied under a constant gas velocity, the mean size based on the major axis of a needle‐like particle decreased from 0.7 µm to 0.4 µm with increasing oxidation rate. By adding of NaH 2 PO 4 to an aqueous Fe(OH) 2 suspension, in concentrations up to 1.0 mol/m 3 during the air oxidation, and up to 0.9 mol/m 3 during the oxidation with 30% and 50% O 2 , the major axis could be reduced to ca. 0.3 µm with the minor axis and the oxidation rate remained almost unchanged.