A novel exfoliated graphite-based device for passive sampling and detection of polycyclic aromatic hydrocarbons in air

Abstract

Water scarcity is a major problem in the Sub-Saharan Africa, as such rainwater harvesting is considered as an alternative source of water. However, air pollution may affect the quality of taken rainwater. Specifically, particle-bound polycyclic aromatic hydrocarbons (PAHs) a class of persistent organic pollutants (POPs) known to have toxic effects on human beings and environmental sectors. In this study, a novel electrode material called exfoliated graphite (EG) was synthesized and used as sorbent material in fabrication of passive sampler and electrode device for the monitoring of polycyclic aromatic hydrocarbons (PAHs) in air. The surface morphology, structure, surface functionality of the materials were investigated using, Scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) techniques. A sorption kinetic’s evaluation of EG was conducted. It was found that EG has shown an outstanding affinity towards detection of PAHs with maximum partition coefficients. Moreover, EG electrode-based device was developed and utilized for detection of PAHs in air through electrochemical technique. This was conducted by exposing the sampler to PAHs gases for 12 days, thereafter it was transferred to a blank supporting electrolyte and analyzed using differential pulse voltammetry (DPV). The EG-based tubular sampler was calibrated in a laboratory flow-through exposure experiment. Furthermore, the effects of time and pollutants concentration were examined under controlled experimental conditions. Most importantly, extraction of the sampler was performed, followed by determination of PAHs using gas chromatography-mass spectrometer (GC–MS). As the result, uptake of PAHs onto the EG tubular based sampler was observed with linear uptake throughout the exposure time. Interestingly, an increasing of uptake by PAHs was indicated when the concentration of the pollutant was increased. These results imply that EG showed a great potential and preferable candidate for monitoring of PAHs in air.