Visibly active Fe-TiO2 composite: A stable and efficient catalyst for the catalytic disinfection of water using a once-through reactor

Abstract This study presents a unique concept of fixed-bed in-situ once-through reactor approaching plug flow (PFR) employed for the disinfection of E. coli. This study discusses the potential applications of a low-cost composite composed of Foundry Sand (FS) and fly ash (FA) for combining hybrid effects. This composite has the intrinsic characteristic of containing iron, which lixiviates in acidic conditions (resulting in photo-Fenton), as well as surface-coated TiO2, which results in photocatalysis, demonstrating a hybrid effect. The surface characteristic analysis of the catalyst (SEM/EDS, XRD, DRS, and FTIR) confirmed the presence of iron (acting as natural dopant) and TiO2 making it visibly active. Therefore showed a significant reduction in the treatment time under solar irradiation with 10% synergy of in-situ hybrid-process over individual processes. The implementation of the in-situ hybrid effect in cascade reactor with three reactors in series helped the reactor approaching PFR with 45 min of retention time (Ʈ) and 100% inactivation of E. coli cell count was observed with optimized operational parameters. The cell wall damage was confirmed by the increase in the K+ concentration at regular intervals. No regrowth of cells after 24 and 48 h of treatment in the dark and sunlight was observed, in completely inactivated samples. Besides this, the Fe-TiO2 composite portrayed an exceptional durability/recyclability efficacy (>100 recycles) under continuous flow conditions. To visualize the practical viability of the proposed high-performance once-through reactor system, the total cost of the treatment process was analyzed in detail.