Magnetic Solid-Phase Extraction Based on Fe3O4/g-C3N4 Nanocomposite for the Determination of Polychlorinated Biphenyls and Polychlorinated Diphenyl Ethers in Environmental Waters

The graphitic carbon nitride (g-C3N4) and the Fe3O4/g-C3N4 magnetic materials were synthesized in this paper. The structures of the materials were confirmed by a series of analysis. The Fe3O4/g-C3N4 was then used as a sorbent to adsorb polychlorinated diphenyl ethers and polychlorinated biphenyls. Different extraction conditions were examined, including adsorbent amount, salinity, pH of the sample matrix, adsorption time, reaction temperature, elution solvent and preconcentration factor. The maximum recoveries were obtained by employing methanol to desorb pollutants on 40.0 mg Fe3O4/g-C3N4 in 120.0 mL environmental water with a salinity of 5% (w/v) at a pH of 7 at 25 °C within 10 min. Using the optimized parameters, the detection limits of the method are between 0.01 and 0.04 μ · L−1 with a satisfying linear relationship. The adsorbent can be recycled at least 10 times with no significant reduction in the extraction efficiency.