The potential of biochar-based catalysts in advanced treatment technologies for efficacious removal of persistent organic pollutants from wastewater: A review

Persistent organic pollutants (POPs) like pharmaceuticals, personal care products, pesticides and surfactants are found at trace environmental concentrations and possess high toxicity toward aquatic and human life. Thus, it is essential to remove POPs from wastewater before it is discharged into the receiving water bodies. Conventional treatment technologies are not efficacious to remediate POPs. In this regard, biochar (BC) based metal composites, which are highly-efficient and a low-cost catalyst, have been used in advanced technologies like photocatalyst, adsorption, electro-Fenton, Fenton-like processes, and catalytic ozonation to degrade POPs. However, owing to certain bottlenecks of raw BC, such as low conductivity, poor adsorption capacity, and low stability, it is vital to modify BC. Thus, the present state-of-the-art review elucidates the application of BC˗based advanced technologies and the basic mechanism involved in the remediation of POPs from wastewater. Moreover, the risk associated with POPs, synthesis procedure, and reusability of BC have been presented in this review. Furthermore, the bottlenecks towards the real-life applications and commercialization of BC˗based catalysts in advanced technologies have also been articulated.