Preconcentration of Pb~(2+) by iron oxide/amino-functionalized silica core-shell magnetic nanoparticles as a novel solid-phase extraction adsorbent and its determination by flame atomic absorption spectrometry

摘要

The use of iron oxide/amino-functionalized silica core-shell magnetic nanoparticles for preconcentration of Pb~(2+) followed by its consecutive atomic absorption spectrometry determination is described. Effects of various operating variables, namely, solution pH, initial Pb~(2+) concentration, contact time, adsorbent dosage, sample volume, concentration and volume of desorbing solution, and co-existing ions on solid-phase extraction (SPE) of Pb~(2+) were studied by batch equilibrium technique. The experimental adsorption data were well fitted to the Langmuir isotherm model. The Langmuir adsorption capacity and equilibrium time were found to be 100 mg g~(-1) and 20 min, respectively. The adsorption data were also fitted to kinetic pseudo-first-order and pseudo-second-order models. Kinetic studies showed that the adsorption followed pseudo-second-order model. Under the optimal SPE conditions, the enrichment factor, detection limit and relative standard deviation for determination of Pb~(2+) were found to be 211, 1 μg L~(-1), and 3.7 % for 50 μg L~(-1), respectively. The proposed method was successfully applied to the determination of lead in a real sample with satisfactory results.