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| Lead (Pb) adsorption on different mineral phases in two soils (Endoaquoll and Plinthudult) was studied using transmission electron microscopy (TEM), energy-dispersive X-ray spectrometry (EDX), and selected area electron diffraction (SEAD) in order to characterize the lead adsorption sites and adsorption capacity of different mineral phases. The adsorption of lead on two soils followed the Langmuir adsorption isotherm with a maximum adsorption capacity of 9460.7 for Endoaquoll and 5662.2 mg kg-1 for Plinthudult, respectively. Among various mineral phases in soils, larger size primary minerals rich in Si and Al were no EDX measurable Pb adsorption, indicating these mineral phases were not main adsorption carriers for Pb. In Endoaquoll, TEM observation and SEAD suggested that Pb carriers of soil consisted of amorphous and crystalline clay mineral phases rich in Si, Al and Fe. The maximum Pb adsorption (8.79 wt.%) was in the crystalline clay phases containing higher amount of Fe. In Plinthudult, Pb was found to be linked to the clay minerals, and amorphous or/and well crystalline iron oxide phases. The relative abundance of Pb in fine clay mineral phases suggested that these mineral phases were main Pb carriers in soils. This study demonstrates that TEM-EDX is an efficient method to investigate metal adsorption in the soil components. |
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| Keywords:Lead (Pb); Soil minerals; Adsorption; Transmission electron microscope (TEM);Energy-dispersive X-ray spectroscopy (EDX) |
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