pH EFFECTS ON LEACHABILITY OF PB-DOPED SOLIDIFIED WASTE FORMS USING PORTLAND CEMENT AND CALCITE |
Dongjin Lee† |
School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia |
Corresponding Author:
Dongjin Lee ,Tel: +61-2-9385-5562, Fax: +61-2-9385-6139, Email: dongj7@empal.com |
Received: July 20, 2004; Accepted: September 20, 2004. |
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ABSTRACT |
This study shows an effect of the pH on leachability of Pb-doped solidified waste forms(SWF) in the Toxicity Characteristic Leaching procedure (TCLP). Since the SWF using Portland cement has sufficient acid neutralization capacity (ANC), the pH of the leachate will be high up to 12 during the early extraction time. The leaching of lead is observed to be occurred initially only in the early and last extraction time because lead species markedly makes insoluble re-precipitates in the pH range of approximately 6-12 during the middle extraction time. In sequential (modified) TCLP, lead was released from Pb-doped SWF(KPIO) in only the Is' and 2nd extraction whilst the pH was greater than 12.0. In all extractions of calcite-additional SWF(KC5P10), insignificant amounts of lead were released because the reaction pH was such that the lead solids present were in their domain of maximum insolubility. |
Keywords:
Cement | CaCOj | Lead | TCLP | pH |
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