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چکیده
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Soils contaminated with heavy metals (HM) are among the common problems of geo-environmental issues all around the world. Modification of clay soils using polymers is an effective method to improve the soils’ geo-environmental properties. Despite the extensive research done on the process of interaction between polymers and clay soils, very limited research has been undertaken in respect to the study of interactions between polymers and contaminated soils. The primary objective of this study was to determine the mechanisms involved in the partitioning and retention of Pb contaminants in interaction with smectite-polymer mixtures. Two procedures for determining the interaction of smectite-polymer mixtures with the HM contaminant Pb were used. In the first procedure, (Procedure A), smectite samples were first exposed to the polymer before being brought into contact with the HM contaminants. In the second procedure, (Procedure B), smectite samples previously contaminated with the Pb were brought into contact with the polymer. Series of batch equilibrium tests, buffering capacity, pH measurements, X-ray diffraction analysis, and scanning electron microscope photograph evaluation were conducted to determine the retention capacity of Pb in these two series of samples. The results state that the addition of 3% polymer to the samples contaminated with 200 cmol/kg-soil Pb contaminant resulted in a 72% increase in Pb contaminant retention relative to the untreated smectite. In general, the results of this study indicate that more effective partitioning of Pb contaminants was achieved with Procedure B samples because of the solidification of the polymer and polymer-bonding mechanisms.
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