Photocatalytic and antimicrobial polymer-based hybrid membranes with surface-modified TiO2 nanoparticles with 5-aminosalicylic acid and silver nanoparticles

Abstract

The sustainability of water treatment is a growing environmental and public health concern, particularly regarding the removal of antibiotics and microorganisms. This study developed multifunctional membranes using synthetic (PVDF-HFP) and natural (silk fibroin, SF) polymer matrices incorporating TiO2 nanoparticles surface-modified with 5-aminosalicylic acid (5-ASA) and silver (Ag). These modifications enhanced both visible-light-responsive photocatalytic activity and antimicrobial performance. The membranes were evaluated for ciprofloxacin degradation and antimicrobial activity against Gram-positive and Gram-negative bacteria. Photocatalytic PVDF-HFP membranes achieved 63% and 62% under UV and simulated solar radiation, respectively, while SF membranes reached 50% and 71%. Antimicrobial efficiency showed a ∼2 log10 bacterial reduction for E. coli and a 0.5 log10 reduction for S. epidermidis, attributed to the presence of Ag in the TiO2/5-ASA nanoparticles. Furthermore, the membranes maintained stable performance across multiple reuse cycles. Overall, the results highlight the potential of these multifunctional materials as efficient and eco-friendly solutions for advanced wastewater treatment applications.