Optimized TiO 2 Coatings on AISI 316 Steel for Advanced Photocatalytic Wastewater Treatment: Mechanism and Performance

High Resolution Image Download MS PowerPoint Slide The development of robust and efficient photocatalysts is essential for sustainable wastewater treatment. This study evaluates the photocatalytic degradation of ciprofloxacin (CIP) using three TiO 2 -coated systems: TiO 2 nanotube arrays (TiO 2 NTA), Bare-Coated TiO 2, and Methanol-Enhanced TiO 2, with a focus on coating uniformity, interfacial stability, and reaction pathways. Surface morphology analysis (SEM) revealed that TiO 2 NTA exhibited a uniform surface, optimizing active site exposure and photocatalytic efficiency. Methanol-Enhanced TiO 2 formed a refined crack pattern, enhancing coating stability and facilitating uniform distribution of TiO 2 particles, while Bare-Coated TiO 2 showed a highly fractured surface, limiting its catalytic efficiency. X-ray diffraction (XRD) confirmed that the anatase phase was the dominant crystalline structure across all coatings, ensuring photocatalytic activity. High-performance liquid chromatography–mass spectrometry (HPLC-MS) analysis revealed distinct degradation patterns, with TiO 2 NTA facilitating rapid fragmentation of CIP into multiple low m / z intermediates, indicating aggressive oxidative breakdown. Methanol-Enhanced TiO 2 exhibited a more controlled degradation pathway, with prominent peaks at 316 (+) m / z and 285 (+) m / z, suggesting selective oxidation and gradual mineralization rather than immediate fragmentation. The degradation mechanism of Methanol-Enhanced TiO 2 likely favored sustained transformation steps, potentially reducing the accumulation of harmful byproducts. Under ultraviolet (UV)-driven photocatalysis, Methanol-Enhanced TiO 2 outperformed Bare-Coated TiO 2, achieving accelerated degradation kinetics, while TiO 2 NTA maintained high stability but lagged in mineralization efficiency. The introduction of ozone further enhanced degradation, ensuring complete CIP removal across all systems. Methanol-Enhanced TiO 2 maintained a degradation efficiency of 88.72% after five reuse cycles, closely matching the 88.75% TiO 2 NTA, demonstrating strong reusability and potential for scalable wastewater treatment applications in photocatalytic treatment reactors. These findings underscore the importance of coating methodologies and interfacial properties in optimizing TiO 2 -based photocatalysts, positioning Methanol-Enhanced TiO 2 as a viable and durable alternative to TiO 2 NTA for sustainable micropollutant removal.