TY - JOUR
T1 - Mechanisms of lead immobilization in treated soils
AU - Dermatas, Dimitris
AU - Menounou, Nektaria
AU - Meng, Xiao Guang
PY - 2006/2
Y1 - 2006/2
N2 - We investigated the leachability and immobilization mechanisms of lead in quicklime- and quicklime-fly-ash-treated artificial soils and lead-contaminated field soils. Artificially prepared clay-sand mixtures with two different types of clays at different clay-sand ratios enabled us to Investigate mineralogical and surface area effects. Batch extraction results indicate that Pb leachability in the montmorillonite-sand mixtures was much lower than in the kaolinite-sand mixtures. The effectiveness of the lime-based treatment was tested with different extraction tests and was compared to other effective immobilization techniques such as cement- and phosphate-based systems. The pH affects lead immobilization, and the apparent pH range of immobilization increases with increasing surface area (addition of fly ash). Lead immobilization was caused either by precipitation, adsorption, or chemical inclusion. However, the solubility of possible Pb precipitates (e.g. carbonate, sulphates, etc.), is much higher than the leachable Pb from both artificial and natural soils. Moreover, chemical extraction at pH 4 showed that much of the Pb is not adsorbed, while quicklim-fly-ash treatment in the artificial soils converted more than 70% of the total Pb to a strongly immobilized form. Therefore, the mechanism controlling the immobilization of Pb in lime-treated contaminated soils seems to be chemical inclusion in the newly formed pozzolanic products.
AB - We investigated the leachability and immobilization mechanisms of lead in quicklime- and quicklime-fly-ash-treated artificial soils and lead-contaminated field soils. Artificially prepared clay-sand mixtures with two different types of clays at different clay-sand ratios enabled us to Investigate mineralogical and surface area effects. Batch extraction results indicate that Pb leachability in the montmorillonite-sand mixtures was much lower than in the kaolinite-sand mixtures. The effectiveness of the lime-based treatment was tested with different extraction tests and was compared to other effective immobilization techniques such as cement- and phosphate-based systems. The pH affects lead immobilization, and the apparent pH range of immobilization increases with increasing surface area (addition of fly ash). Lead immobilization was caused either by precipitation, adsorption, or chemical inclusion. However, the solubility of possible Pb precipitates (e.g. carbonate, sulphates, etc.), is much higher than the leachable Pb from both artificial and natural soils. Moreover, chemical extraction at pH 4 showed that much of the Pb is not adsorbed, while quicklim-fly-ash treatment in the artificial soils converted more than 70% of the total Pb to a strongly immobilized form. Therefore, the mechanism controlling the immobilization of Pb in lime-treated contaminated soils seems to be chemical inclusion in the newly formed pozzolanic products.
KW - Contamination
KW - Fly ash
KW - Immobilization
KW - Leaching
KW - Lead
KW - Lime
KW - Mechanisms
KW - Soil
KW - Stabilization
KW - TCLP
UR - http://www.scopus.com/inward/record.url?scp=33644827428&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33644827428&partnerID=8YFLogxK
U2 - 10.2462/09670513.702
DO - 10.2462/09670513.702
M3 - Article
AN - SCOPUS:33644827428
SN - 0967-0513
VL - 14
SP - 43
EP - 56
JO - Land Contamination and Reclamation
JF - Land Contamination and Reclamation
IS - 1
ER -