期刊
JOURNAL OF HAZARDOUS MATERIALS
卷 122, 期 1-2, 页码 85-90出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jhazmat.2005.03.010
关键词
soil washing; copper; EDTA; leaching mechanism
A series of 24 h batch tests of copper extraction from a sandy soil were performed by washing the soil with aqueous solution of ethylenediaminetetraacetic acid, EDTA. EDTA versus copper molar ratio were in the range between 1 (equimolar tests) and 13.3. The tests were performed at three selected liquid/solid ratio, 5, 12.5 and 25. Results show that decreasing the pH of the washing solution an higher copper extraction yield was achieved: an almost complete copper extraction was achieved after 23 h of mixing at a US = 5, and after 5 h of mixing at an US = 12.5. The mechanism of copper extraction was found to involve two sequential processes: the former dissolution of metal salts, that lead to an initial high concentration of both copper and some competitive cations (essentially Ca2+), and the following EDTA exchange reaction between calcium and copper complexes, which corresponded an increase of pH in the washing solution. A negligible extraction of Fe3+ was also observed at the investigated operative conditions. (c) 2005 Published by Elsevier B.V.
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