Preparation and Maghemite Using Waste Pickling Acid

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J. Korean Ceram. Soc. > Volume 28(12); 1991 > Article

Journal of the Korean Ceramic Society 1991;28(12): 996.

산세폐액을 이용한 Maghemite의 제조

변태봉, 이재영, 김대영, 손진군, 권순주¹

산업과학기술연구소
¹포항공과대학

Preparation and Maghemite Using Waste Pickling Acid

ABSTRACT

In this study, we tried to synthesis iron hydroxide suitable for longitudinal magnetic recording media from waste acid, which is a by-product of an iron works factory. Effects of initial pH of reactants, reaction temperature, reaction time for the synthesis of acicular iron hydroxide were studied in relation to particle properties of iron hydroxide and magnetic properties of maghemite powders. As the pH in reactant solution increased, $beta$-FeOOH(pH=4.5), mixture of $beta$-FeOOH and $alpha$-FeOOH(4.5$alpha$-FeOOH and Fe3O4(6.4$alpha$-FeOOH (pH>13) was found to from in order. Especially, $alpha$-FeOOH formed above pH 13 was single phase with superior acicularity. The temperature range over which the single-phase goethite can be formed increased as the initial pH of reactants increased (pH 13:10~5$0^{circ}C$, pH 13.2:10~7$0^{circ}C$, pH 13.5:0~8$0^{circ}C$). The goethite formed between 40~6$0^{circ}C$ has superior characteristics because the acicularity increased with increasing temperature but at high temperature (>6$0^{circ}C$) Fe3O4 (pH=13) was found to start to form. Generally, single phase of goethite was found to form after one hour when an optimized condition. The particle size of goethite did not change as the reaction time increased over one hour. Accordingly, the magnetic properties of ${gamma}$-Fe2O3 produced from goethite were not altered.