SYNTHESIS OF NANO-SIZED IRON FOR REDUCTIVE DECHLORINATION. 2. Effects of Synthesis Conditions on Iron Reactivities |
Hocheol Song1, Elizabeth R. Carraway1, and Young-Hun Kim2† |
1Department of Environmental Engineering and Science, Clemson University, 342 Computer Court, Anderson, SC 29625 2Department of Environmental Engineering, College of Engineering, Andong National University, Andong, KyungPook 760-749, Korea |
Corresponding Author:
Young-Hun Kim ,Tel: +82-054-820-5818, Fax: +82-054-820-6187 , Email: youngkim@andong.ac.kr |
Received: February 8, 2005; Accepted: July 7, 2005. |
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ABSTRACT |
Nano-sized iron was synthesized using borohydride reduction of FeJ in aqueous solution. A wide range of synthesis conditions including varying concentrations of reagents, reagent feeding rate, and solution pH was applied in an aqueous system under anaerobic condition. The reactivity of nano-sized iron from each synthesis was evaluated by reacting the iron with TCE in batch systems. Evidence obtained from this study surggest the reactivity of iron is strongly dependent on the synthesis solution pH. The iron reactivity increased as solution pH decreased. More rapid TCE reduction was observed for iron samples synthesized from higher initial FeJ concentration, which resulted in lower solution pH during the synthesis reaction. Faster feeding of BELT solution to the Fe3+ solution resulted in lower synthesis solution pH and the resultant iron samples gave higher TCE reduction rate. Lowering the pH of the solution after completion of the synthesis reaction significantly increased reactivity of iron. It is presumed that the increase in the reactivity of iron synthesized at lower pH is due to less precipitation of iron (hydr)oxides or less surface passivation of iron. |
Keywords:
zero-valent metals | nano-particle | pH | borate injection rate | reduction | dechlorination |
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