Adsorption and determination of polycyclic aromatic hydrocarbons in water through the aggregation of graphene oxide

In this study, a simple method was developed for the aggregation of graphene oxide (GO) with the addition of NaCl to concentrate and separate polycyclic aromatic hydrocarbons (PAHs) from water samples, and this method was used as a environmentally friendly method for the determination of PAHs. We demonstrate the uniform dispersion of GO sheets in aqueous samples for the fast high-efficiency adsorption of PAHs. Aggregation occurred immediately upon elimination of electrostatic repulsion by adding NaCl to neutralize the excessive negative charges on the surfaces of the GO sheets. The aggregates of GO and PAHs were separated and treated with hexane to form a slurry. The slurry was filtered and subjected to gas chromatography mass spectroscopy (GC-MS) analysis. Based on a 40-mL sample volume, limits of detection of 10-30 ng L-1 were obtained for 16 PAHs, with correlation coefficients (R-2) exceeding 0.99. The method yielded good recovery, ranging from 80 to 111% and 80 to 107% for real spiked water samples at 100 and 500 ng L-1, respectively. Compared to traditional solid-phase extraction and liquid-liquid extraction methods, this method is free of organic reagents in the pretreatment procedure and uses only 1 mL hexane for sample introduction.