Highly efficient ultrasonic-assisted preconcentration of trace amounts of Ag(I), Pb(II), and Cd(II) ions using 3-mercaptopropyl trimethoxysilane-functionalized graphene oxide–magnetic nanoparticles

The preparation and characterization of thiol-functionalized graphene oxide–iron oxide (Fe3O4–GO–SH) nanocomposites (novel magnetic adsorbents) for the simultaneous preconcentration and determination of heavy metal ions, such as Ag(I), Pb(II), and Cd(II), from water samples were carried out in the present research. The characterization of the resultant Fe3O4–GO–SH nanocomposites was performed by SEM, TEM, EDX, XRD, FT-IR, and VSM. The preconcentration optimization of pH solution, adsorbent amount, ultrasonic power for adsorption and desorption processes, adsorption time, and elution solvent type and concentration was performed by the ultrasonic-assisted magnetic solid-phase extraction. Under optimal conditions, linear ranges were found to be 20–1000 μg L–1 for Ag(I) and Cd(II) ions and 200–10,000 μg L–1 for Pb(II) ions with a regression coefficient of R2 > 0.99. The limits of detection for Ag, Pb, and Cd ions were 1.7 μg L–1, 14.1 μg L–1, and 0.9 μg L–1, respectively, and the limits of quantification for Ag, Pb, and Cd ions were 5.9 μg L–1, 47.3 μg L–1, and 3.2 μg L–1, respectively. The recovery rate of these metal ions for water samples (drinking water, tap water, swamp water, and wastewater from plating plants) ranged between 80 and 115%. Therefore, the proposed method can potentially be used for the simultaneous preconcentration and determination of heavy metal ions from real water samples, and its reusability can be easily carried out by the deionized water treatment.