Combined Effect of Adsorption and Photocatalysis for the Removal of Ciprofloxacin from Aqueous Solutions with Poly(Vinylidene Fluoride)/Titanium Dioxide Microspheres

Significant amounts of antibiotics are found in wastewater and drinking water streams due to their widespread use in human and veterinary medicine and their incomplete uptake by living organisms. Among the technologies developed to address this problem, adsorption and advanced oxidation processes, including photocatalysis, are widely employed for the remediation of antibiotic-contaminated waters. In this work, poly(vinylidene fluoride) (PVDF)/TiO2 composite microspheres with highly porous structures were developed and evaluated for the removal of ciprofloxacin (CIP) from aqueous solutions. Scanning electron microscopy revealed that TiO2 nanoparticles migrate towards the microsphere surface during PVDF crystallisation, forming a dense surface coating, whereas the microsphere interior remains highly porous. Focused ion beam microscopy confirmed the presence of TiO2 within the inter-spherulitic regions of the microsphere core. A key finding is that a pre-wetting protocol facilitates water penetration into the highly hydrophobic PVDF structure, enabling efficient CIP adsorption in the dark, while untreated microspheres show only limited adsorption. This work demonstrates that CIP removal by porous PVDF/TiO2 microspheres is associated with both the surface segregation of TiO2 nanoparticles and the accessibility of the porous structure to water. These findings emphasise the importance of pore accessibility in the design of porous polymer-based materials for water treatment.