Silica-coated magnetic graphene oxide nanocomposite based magnetic solid phase extraction of trace amounts of heavy metals in water samples prior to determination by inductively coupled plasma mass spectrometry

Abstract

The silica-coated magnetic graphene oxide (Fe3O4-GO@SiO2) composites were synthesized by a simple procedure in this work. The nanocomposite was characterized and applied for the rapid magnetic solid-phase extraction (MSPE) of chromium (Cr), cobalt (Co), nickel (Ni), copper (Cu), cadmium (Cd), lead (Pb), silver (Ag) ions at trace level in environmental water samples. Various experimental parameters affecting the extraction efficiency of the target metal ions by Fe3O4-GO@SiO2 were investigated and optimized, including sorbent dosage, pH of sample solution, sorption time, volume and eluent concentration, as well as elution time. Under the optimal conditions, the limits of detection (LODs, 3σ) for the target analytes were obtained in the range of 2.023–13.810 ng L−1. The recoveries of the target metals in four environmental water samples ranged from 83% to 109% and the relative standard deviations (RSDs) were lower than 7%. Moreover, in batch adsorption experiments, the adsorption of these seven metal ions was relatively speedy and the equilibrium was established after shaking 35 min which kinetics followed the pseudo second-order model, indicating a chemisorption nature. The adsorption process was simulated by the Langmuir isotherm accurately, and the calculated maximum adsorption (qmax) capacities of Fe3O4-GO@SiO2 were 182.98 mg g−1, 116.35 mg g−1, 226.08 mg g−1, 149.59 mg g−1, 100.81 mg g−1, 168.55 mg g−1 and 141.09 mg g−1 for Cr (III), Co (II), Ni (II), Cu (II), Cd (II), Pb (II) and Ag (I), respectively. Finally, the developed method was successfully applied for simultaneous and sensitive determination of target metals at trace level in environmental water samples.