Remediation and cytotoxicity study of polycyclic aromatic hydrocarbon-contaminated marine sediments using synthesized...

The study developed a new and cost-effective method for the remediation of marine sediments contaminated with polycyclic aromatic hydrocarbons (PAHs). Iron oxide (Fe₃O₄) nanoparticles were synthesized as the active component, supported on carbon black (CB), to form a composite catalyst (Fe₃O₄-CB) by using a wet chemical method. The oxidation of 16 PAH contaminants present in marine sediments significantly activated sodium persulfate (Na₂S₂O₈) to form sulfate free radicals (SO₄^-·); this was investigated in a slurry system. In addition, in vitro cytotoxic activity and oxidative stress studies were performed. The synthesized composite catalysts (Fe₃O₄-CB) were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, a superconducting quantum interference device magnetometry, and environmental scanning electron microscopy. The efficiency of PAH removal was 39-63% for unactivated persulfate (PS) from an initial dose of 1.7 × 10^-7-1.7 × 10^-2 M. The removal of PAHs was evaluated using Fe₃O₄/PS, CB/PS, and Fe₃O₄/PS and found to be 75, 64, and 86%, respectively, at a temperature of 303 K, PS concentration of 1.7 × 10^-5 M, and pH of 6.0. An MTT assay was used to assess the cytotoxicity of the composite catalyst at five concentrations (25, 50, 100, 200, and 400 μg/mL) on human hepatoma carcinoma (HepG2) cells for 24 h. This revealed a dose-dependent decrease in cell viability. A dichlorofluorescein diacetate assay was performed to evaluate the generation of reactive oxygen species, which principally originated from the ferrous ions of the composite catalyst.