Extraction and preconcentration of Pb(II) from water and soil samples using modified activated carbon

In this work, a new extractant was prepared by immobilizing ligand 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol, (5-Br-PADAP), on the activated carbon and, then, applied to extraction of Pb(II) prior to determination by flame atomic absorption spectrometry. It was confirmed by FT- IR analysis. The metal ion was retained on the 0.05 g of the sorbent in the pH range 6-8, and then eluted with 5 mL of 0.5 mol L^-1 nitric acid. Seven replicate determinations of a 1.0 μg mL^-1 of lead solution in the final solution gave relative standard deviation of ±3.3%. The maximum equilibrium capacity of the new sorbent from Langmuir model was 18.2 mg g^-1. The linearity was maintained in the concentration range of 0.1-10.0 ng mL^-1 for the concentrated solution. The limit of detection based on three times the standard deviation of the blank (3σbl/m), was found to be 0.83 ng mL^-1 in original solution. Common coexisting ions did not interfere with the separation and determination of the lead. The prepared sorbent was applied to the preconcentration of Pb(II) in water and soil samples with satisfactory results.