| 摘要 |
PURPOSE:To obtain goethite with excellent acicularity by a method wherein ferric salt solution is added to alkali hydroxide solution and colloid of ferric hydroxide is precipitated in an alkaline region in which pH has a specific value and alkali carbonate is added to this suspension and aged. CONSTITUTION:2.5l of water solution of ferric chloride of 1.25mol is added to 1.5l of solution of sodium hydroxide of 2.5mol/l. After the mixed solution is stirred and colloid of ferric hydroxide is procuced, more solution of sodium hydroxide of 2.5mol/l is added to make pH of colloidal suspension 9.0-12.0. After that, the solution is stirred and mixed completely and 500ml of solution of sodium carbonate of 2.5mol/l is added to it and the mixed solution is sterred and mixed again. Then this ferric hydroxide colloid suspension is aged at 45 deg.C for 120hr and alpha-FeOOH particles are produced. With this constitution, a needle- shape crystal, whose long axis is 0.37mum and short axis is 0.03mum is obtained. |
