Development of Novel Polymer Supported Nanocomposite GO/TiO₂ Films, Based on poly(L-lactic acid) for Photocatalytic Applications

In the present study the development of novel polymer-supported nanocomposite graphene oxide (GO)–TiO₂ films, based on poly(L-lactic acid), one of the most exploited bioplastics worldwide, was explored for photocatalytic applications. The nanocomposites were synthesized and evaluated as photocatalysts for the removal of a mixture of nine antibiotics, consisting of two sulphonamides (sulfamethoxazole, sulfadiazine), three fluoroquinolones (levofloxacin, norfloxacin, moxifloxacin), one anti-TB agent (isoniazid), one nitroimidazole (metronidazole), one lincosamide (lincomycin) and one diaminopyrimidine (trimethoprim), which are commonly found in wastewaters. The films were synthesized using 1 wt% GO and different TiO₂ content (10, 25, and 50 wt%) and characterized using Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Findings confirmed the successful immobilization of GO/TiO₂ in all cases. The PLLA–GO–TiO₂ 50 wt% composite film demonstrated higher photocatalytic efficiency and, thus, was further investigated demonstrating excellent photostability and reusability even after four cycles. Overall, PLLA–GO–TiO₂ 50 wt% nanocomposite demonstrated high efficiency in the photocatalytic degradation of the antibiotics in various matrices including pure water and wastewater.