Three-dimensional multi-walled carbon nanotubes@g-C3N4@Fe3O4nanocomposites-based magnetic solid phase extraction for the determination of polycyclic aromatic hydrocarbons in water samples

In this study, three-dimensional multi-walled carbon nanotubes@g-C3N4@Fe3O4 nanocomposites (3D MWNTs@g-C3N4@Fe3O4 nanocomposites) were prepared and used as a novel magnetic solid phase extraction (MSPE) sorbent for the analysis of 16 polycyclic aromatic hydrocarbons (PAHs). The novel nanocomposites were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), and vibrating sample magnetometer (VSM) methods. To achieve the best extraction efficiency, several experimental parameters, including sorbent amount, extraction time, stirring rate, ionic strength, desorption solvent, desorption volume and desorption time, were optimized. Under the optimized preparation and extraction conditions, the proposed method showed the limits of detection (LODs) for polycyclic aromatic hydrocarbons (PAHs) were found to be in the range of 0.001-0.5 μg L−1, limits of quantification (LOQs) were in the range of 0.005-0.8 μg L−1 and their relative standard deviations (RSDs) were lower than 5.0%. The proposed MSPE method was applied successfully in the analysis of PAHs in rainwater, river water and industrial wastewater samples. The recovery of the PAHs in all samples spiked with 5 g L−1 ranged from 82.4 to 116.9% with RSDs below 9.7%.