Degradation of PAHs using TiO2 as a semiconductor in the heterogeneous photocatalysis process: A systematic review

[Display omitted] •In the literature, data on degradation of PHA mixtures are scarce, only isolated molecules.•Systematic review of the photocatalytic process of PAHs, with its advantages and disadvantages.•Around 99% PAHs degradation with pellets obtained using TiO2. Polycyclic Aromatic Hydrocarbons (PAHs) are organic compounds formed by benzene rings fused in their structure, arranged in different ways, and may have different radicals and organic functions. The contamination of soil, air, and water environments has increased, and studies of alternative remediation of contaminated sites. Removal of PAHs in the medium can be done by a series of techniques such as biofiltration, biodegradation; adsorption; and phytoremediation. One method that has been widely studied is heterogeneous photocatalysis. It is an Advanced Oxidative Process (AOP) and alternative technology to those traditionally used and can degrade toxic organic compounds of environmental relevance until their complete mineralization. This article aims to present a systematic review on the action of Advanced Oxidative Processes, in particular heterogeneous photocatalysis, used by titanium dioxide (TiO2) on PAH. This systematic review presents the main information obtained from 86 research articles, taken from four databases, on advanced oxidative processes, heterogeneous photocatalysis, and the use of TiO2 in the degradation of PAHs. In addition, we present a discussion on how these reaction mechanisms, the formation of reaction sub-products, and verifying the need for experimental studies that detect the toxicity of the formed compounds and compare them with the initial reaction molecules. It should be noted that experimental studies of heterogeneous photocatalysis for PAH degradation are needed to clarify whether there was the formation of more toxic compounds, as well as in vitro and in vivo toxicity, in addition, of course, to the formation of CO2 and H2O, which are the products desired at the end of the reaction, which would not harm the aquatic biota nor cause harm to human beings.