Remediation and cytotoxicity study of polycyclic aromatic hydrocarbon-contaminated marine sediments using synthesized iron oxide-carbon composite

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 (-center dot)); 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 x 10(-7)-1.7 x 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 x 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 mu g/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.