Recent advances in the treatment of PAHs in the environment: Application of nanomaterial-based technologies

Polycyclic aromatic hydrocarbons (PAHs) are one of the most frequent petroleum hydrocarbons detected in the environment. PAHs are receiving global attention due to their toxicity, environmental persistence, and potential bioaccumulation. PAHs contamination occurs mainly due to anthropogenic sources related to the disposal of industrial and domestic run-offs or atmospheric emissions from plants or vehicles. Once PAHs are introduced into the environment, they undergo different processes either physical, chemical, or biological transformations, which are collectively known as weathering processes. These weathering processes are highly dependent on the nature and the physiochemical properties of PAHs molecules and the surrounding environment, which eventually will determine their transport, fate, and distribution in the environment either through adsorption to soil/sediments, or volatilization to the atmosphere, or dissolution in the water. Different treatment strategies for PAHs pollution have been introduced. Each remediation technology has its advantages and disadvantages. To choose a treatment, a full analysis of the case study should be provided, including the properties of the target pollutant, site description, and treatment procedure. As the treatment of PAHs contaminated sites is usually a difficult and expensive task, it would be a good choice to go for treatment, which is adaptive, sustainable, eco-friendly, efficient, and cost-effective. In this review, the transport, fate, and distribution processes of PAHs in the environment with their dependent factors were elaborated. In addition, this paper provided an overview of different traditional and advanced potential treatment approaches used to treat PAHs-contaminated sites such as thermal, chemical, electrokinetic, nano-adsorption, and biological treatments.