The increasing presence of pharmaceutical contaminants in wastewater demands efficient and sustainable treatment methods, with photocatalysis emerging as a promising solution. In this study, a nitrogen-iron co-doped TiO2 (N-Fe/TiO2) heterojunction photocatalyst was synthesized via the sol-gel method to enhance visible-light absorption and charge separation efficiency. The catalyst was immobilized on the outer surface of a quartz tube using a dip-coating technique, ensuring uniform distribution and stability during continuous operation. The photocatalytic degradation of pharmaceutical waste was conducted in a continuous-flow reactor under visible light irradiation (150 W lamp) transmitted through an optical fiber, enabling efficient and uniform light distribution. The N-Fe/TiO2 heterojunction was extensively characterized using X-ray diffraction (XRD), which confirmed the anatase/rutile phase composition, while scanning and transmission electron microscopy (SEM/TEM) revealed its nanostructured morphology. X-ray photoelectron spectroscopy (XPS) verified successful nitrogen and iron doping, and UV-Vis diffuse reflectance spectroscopy (DRS) demonstrated a narrowed bandgap, extending light absorption into the visible region. Additionally, photoluminescence (PL) spectroscopy confirmed reduced electron-hole recombination, further boosting photocatalytic efficiency. The reactor’s continuous-flow design allowed for real-time degradation assessment, with liquid chromatography mass spectroscopy (LC-MS) and total organic carbon (TOC) analysis confirming significant pharmaceutical pollutant mineralization. The dip-coating immobilization method ensured long-term catalyst stability, preventing leaching and maintaining consistent degradation efficiency over multiple cycles. This study highlights the effectiveness of the N-Fe/TiO2 heterojunction as a robust visible-light-driven photocatalyst, offering a sustainable and scalable solution for pharmaceutical wastewater treatment. The integration of optical fiber-based illumination and a continuous-flow reactor design presents a practical approach for large-scale environmental remediation, demonstrating the potential of advanced photocatalytic systems in addressing water pollution challenges.
