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The effect of pH on the citrate leaching behavior of heavy metal ion was investigated to develop an eco-friendly process forremoving heavy metals from soil contaminated with copper, zinc, and lead. The leaching tests were performed using citrate solu-tion with pH adjusted by mixing citric acid and sodium citrate under the following leaching conditions: particle size, under75 µ m; temperature, 50 o C; citrate concentration, 1 kmol/m 3 ; pulp density, 5%; shaking speed, 100 rpm; leaching time, 1 hour.The difference of pH before and after the leaching test was not observed, and this result indicates the direct effect of hydrogenion concentration on the leaching of metals was insignificant. The removal ratios of copper, zinc, and lead from the contaminatedsoil decreased with increasing pH. The thermodynamic calculation suggests that the leaching behaviors of metal ions were deter-mined by two reactions; one is the reaction to form complex ions between heavy metal ions and citrate ion species, and the otheris the reaction to form metal hydroxide between heavy metal ions and hydroxide ion. Key words : citrate, heavy metals, contaminated soil, leaching behavior * Received : February 14, 2013·Revised : March 11, 2013·Accepted : March 20, 2013Corresponding Author : Kyoungkeun Yoo (E-mail : kyoo@kmou.ac.kr)Department of Energy & Resources Engineering, Korea Maritime University, 727 Taejong-ro Youngdo-gu Busan, 606-791, KoreaTel : +82-51-410-4686 / Fax : +82-51-403-4680ⓒThe Korean Institute of Resources Recycling. All rights reserved. This is an open-access article distributed under the termsof the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permitsunrestricted non-commercial use, distribution and reproduction in any medium, provided the original work is properly cited. |
