Plant Extract-Mediated Synthesis of Nano-Crystallite TiO2 for the Efficient Photocatalytic Degradation of Textile Effluent and Antibiotics.

Anatase phase TiO2 nanoparticles were successfully synthesized in this work utilizing extracts from five distinct plant species, such as Dillenia indica, Mikania micrantha, Pistia stratiotes, Ocimum sanctum, and Caesalpinia pulcherrima. The produced samples underwent characterization employing a range of approaches, including x-ray diffraction (XRD), thermal weight loss analysis, Fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive x-ray spectroscopy (EDX), and optical band gap energy estimation. The XRD and FT-IR analyses provided confirmation of anatase-phase TiO2 fabrication, and XRD parameters were used to calculate crystallite sizes using various XRD models, ranging from 1 to 70 nm, except the linear straight-line method had a higher estimate. FESEM revealed spherical-shaped nanoparticles, and EDX analysis validated the purity of the samples. Moreover, thermal weight loss analysis confirmed their thermal stability. The photodegradation performance of the TiO2 nanoparticles was demonstrated with complete degradation (100%) of Congo red dye and 94.51% degradation of ciprofloxacin antibiotic when subjected to visible light exposure. The superior photocatalytic performance was corroborated by the estimated optical band gap, which indicated improved visible-light absorption and efficient separation of photogenerated charge carriers. The underlying photodegradation mechanism, as revealed by scavenging experiments, demonstrated that hydroxyl radicals (•OH) and photogenerated holes (h⁺) are the dominant reactive species, acting synergistically to drive the decomposition of both the dye and pharmaceutical contaminants.