Upcycling of waste EPS beads to immobilized codoped TiO2 photocatalysts for ciprofloxacin degradation and E. coli disinfection under sunlight

Abstract

The emerging global problem of antimicrobial resistance needs immediate attention. In this regard, this work demonstrates the use of expanded polystyrene waste in the synthesis of immobilized photocatalytic films for the treatment of antibiotics as well as for bacterial disinfection. A boron–cerium codoped TiO<inf>2</inf> catalyst (of specific composition: B<inf>0.8</inf>Ce<inf>0.2</inf>TiO<inf>2</inf>) was immobilized in an expanded polystyrene (EPS) film prepared from waste EPS beads. These films were studied for the degradation of ciprofloxacin (CIP) and disinfection of E. coli under sunlight. The film with a catalyst loading of 20 wt% showed a maximum degradation of 89% in 240 min with a corresponding TOC reduction of 84%. A 7.4 and 6.3 log reduction from the bacterial inactivation studies in the presence and absence of antibiotics, respectively, was obtained. The EPS film was stable after five times of reuse, and no significant chemical changes in the used film were observed from FTIR analysis. The average thickness of the prepared film was found from FESEM analysis to be 1.09 mm. These EPS films were also tested for degradation of other antibiotics, such as norfloxacin, levofloxacin and moxifloxacin. The EPS films were tested in two different reactor volumes at optimum conditions. Also, the effectiveness of B<inf>0.8</inf>Ce<inf>0.2</inf>TiO<inf>2</inf>/EPS film in real water samples indicates its potential in large-scale and real-world applications. Thus, these B<inf>0.8</inf>Ce<inf>0.2</inf>TiO<inf>2</inf>/EPS films can be effectively employed for both degradation of ciprofloxacin and the disinfection of E. coli under solar light to solve the increasing problem of antimicrobial resistance. © 2023, Springer Nature Limited.