Insight into the extractability of metals from soils using an implementation of the linear adsorption isotherm model |
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Authors: | Johannes T van Elteren Bojan Budi? |
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Institution: | National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia |
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Abstract: | This paper deals with an often overlooked artifact in sequential and single extraction of metals from soils, viz. the volume to mass (V/m) ratio as a potential source for inadequate extraction yields. We offer a theoretical framework to get a grip on this intricate parameter and came up with a model based on a linear adsorption isotherm to derive the correct maximal metal extractability for a certain extractant. We verified the model experimentally using 0.1 mol l−1 nitric acid for extraction of seven metals (Cr, Co, Cu, Cd, Pb, Ni and Zn) from an urban soil sample, and concluded that commonly used V/m ratios in the range of 10-40 ml g−1 may give as much as 50% too low extraction yields. Thus, a strong caveat is in place as to be very critical what V/m ratios to use and preferably apply the model derived to obtain the correct maximal extractability using a variable V/m ratio method. |
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Keywords: | Extraction Metal Soil Linear adsorption isotherm Partitioning coefficient |
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