Biochar-derived photocatalysts for pharmaceutical waste removal, a sustainable approach to water purification

In the past few years, the utilization of pharmaceutical compounds has considerably increased to treat human and animal diseases. The pharmaceutical waste, processed or unprocessed, is being released into water systems. This contamination leads to the death of millions of people across the globe annually. Tailored treatment procedures are effectively employed to remove these compounds. However, many of these techniques suffer from high-cost apparatus, generation of secondary pollutants, and sludge etc. Conversely, adsorption combined with photocatalysis is an alternative, economical and efficient method for water remediation. This review delves deeper into the synthesis protocols of biochar derived photocatalysts and investigates their water purification applications. Specifically, studies focusing Fluoroquinolones, Tetracyclines, non-steroidal anti- inflammatory drugs (NSAIDs), Sulfa drugs, anti-bacterial, antiviral and anti-convulsant drugs have been explored. The degradation pathways of these drugs have been elucidated in detail along with the reaction parameters and kinetic studies. Notably, the highest removal efficiency reported to date for these drugs is 100 % with recyclability up to 8 cycles, maintaining minimal efficacy decline. Literature has explained that the use of bare biochar does not perform effectively. On the contrary, combining it with other materials including metal oxides, MOFs, CNTs significantly enhances its efficiency. The practical implementation of BC nanocomposites in the real-world water systems is in infancy and requires scalability. Moreover, the regeneration studies of the photocatalysts are restricted to fewer cycles and needs upgradation. This review aims to open avenues for future research in the domain of photocatalytic degradation of pharmaceutical waste in wastewater.