DEFECT-ENGINEERED NANOCOMPOSITE MATERIALS FOR ENHANCED PHOTOCATALYTIC REMOVAL OF EMERGING PHARMACEUTICAL POLLUTANTS FROM PAKISTANI WATER SOURCES

Abstract

Pharmaceutical residues in aquatic environments represent an emerging environmental challenge because of their persistence, biological activity, and incomplete removal by conventional wastewater-treatment processes. This study investigated the potential of defect-engineered nanocomposite materials for enhanced photocatalytic removal of emerging pharmaceutical pollutants from water sources in Pakistan. A quantitative laboratory-based experimental framework was developed to compare pristine photocatalysts, non-defective nanocomposites, and defect-engineered nanocomposites. Material performance was evaluated through structural, morphological, optical, surface, and charge-transfer characterization, followed by controlled photocatalytic degradation experiments. The analysis considered pollutant removal efficiency, apparent degradation kinetics, mineralization, reactive oxygen species generation, operational conditions, water-matrix effects, and catalyst reusability. The results showed that the defect-engineered nanocomposite achieved 91.6% pharmaceutical removal and an apparent first-order rate constant of 0.0248 min⁻¹, compared with 58.4% and 0.0086 min⁻¹, respectively, for the pristine photocatalyst. TOC removal reached 78.9%, indicating substantial mineralization in addition to parent-compound degradation. Statistical analysis indicated significant differences among photocatalyst configurations, while mechanistic analysis suggested that improved charge separation, reduced recombination, enhanced interfacial transfer, and reactive oxygen species generation contributed to the observed performance. Removal efficiency decreased in complex Pakistani water matrices compared with synthetic water, highlighting the importance of environmental-matrix effects. The findings provide an integrated structure–defect–interface–mechanism–performance framework for developing advanced photocatalytic materials for pharmaceutical-contaminant remediation.