A Nanocomposite Based on Dipyridylamine Functionalized Magnetic Multiwalled Carbon Nanotubes for Separation and Preconcentration of Toxic Elements in Black Tea Leaves and Drinking Water

A novel functionalized magnetic multiwalled carbon nanotube composite was prepared and utilized as a nanosorbent for separation and preconcentration of Cr(III), Cd(II), Cu(II), Pb(II), and Ni(II) ions. The synthesized nanosorbent was characterized with various techniques. The parameters influencing the preconcentration efficiency were optimized through experimental design methodology by using Box-Behnken design method. Uptake time, pH of sample, and magnetic nanosorbent amount were evaluated in the sorption step as the main affecting factors, while four variables including type, volume, concentration of the eluent, and elution time were considered in the elution step. After sorption and elution steps, the target analytes were determined by flame atomic absorption spectrometry. Limit of detection was 0.5, 0.08, 0.7, 0.4, and 0.1 ng mL(-1) for Cr(III), Cu(II), Pb(II), Ni(II), and Cd(II) ions, respectively. All relative standard deviations of the method were < 9.5%. The capacity of the sorbent ranged between 184 and 215 mg g(-1). Finally, the developed method was successfully applied to the rapid extraction of trace amounts of these ions from black tea leaf samples and drinking water.