A review on eco-sustainable photocatalytic degradation of pharmaceutical pollutants using biosynthesized nanoparticles

Pharmaceutical substances, a pill for every ill, have become a sweet poison by remarkably boosting the global economy as well as human and animal wellness and at the same time causing environmental pollution, especially in the aquatic ecosystem, and this has led to a fatal diminution in the availability of clean water and upsurge in water insecurity. Notably, traditional techniques and materials have been employed to clean up pharmaceutical pollutants (PP) from aquatic bodies; however, they have come under controversy because they require hazardous chemicals and cannot fully mineralize stubborn PPs. Interestingly, the photocatalytic degradation approach employing eco-benign biosynthesized nanoparticles (BNP) is an avant-garde practice and has shown to be an eco-sustainable method that can fully mineralize PPs into harmless molecules. Thus, this study critically explores the application of BNPs for the photocatalytic degradation of PPs. The review revealed that the greatest degradation efficacy of BNPs was greater than 80% in most cases, and that the least amount of time required was around 10 min. In addition, the oxygen-containing functional groups found in the biological sources used for the fabrication of BNPs contributed to the supremacy of ^•OH and O₂^• radicals in the degradation operation. Also, the photocatalytic degradation kinetic data was well modeled by pseudo-first order, and this indicates that ^•OH was more involved in the PPs degradation operation than O₂^•. Moreso, BNPs have excellent reusability potential (>5 rounds) while maintaining inherent structural integrity. Techno-economic analysis revealed that BNPs are cost-effective, costing about $1.5/1,000,000 mL of pharmaceutical wastewater on average.