Comparative Study on Photocatalytic Performance of TiO2 Doped with Different Amino Acids in Degradation of Antibiotics

In this study, three different reusable photocatalysts containing amino acids as a source of non-metals, including L-Arginine, L-Proline, and L-Methionine, have been synthesized for the first time. Using kinetic study degradation efficiency test, these visible driven were investigated their photocatalytic activity in removing antibiotics, metronidazole (MNZ) cephalexin (CEX). The morphology, structure optical properties fabricated catalysts characterized by X-ray Powder Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive Spectrometry (EDS)/mapping, Fourier-Transform Infrared Spectroscopy (FTIR), Photoluminescence (PL) UV-Vis Diffuse Reflectance (DRS) analyses. Based on results PL analysis, it was confirmed that doping TiO2 with C, N, S inhibited recombination induced electrons holes. Among catalysts, L-Arginine-TiO2 demonstrated highest antibiotic degradation, followed L-Proline-TiO2. According to response surface methodology (RSM), optimum operating conditions concentration 50 mg/L MNZ, pH = 4, catalyst 1.5 g/L under 90 min irradiation At condition, 99.9% MNZ 81% TOC removed. addition, 97.2% CEX 75% eliminated at 1g/L concentration, neutral pH, after 120 irradiation. L-Arginine (1 wt.%)-TiO2 tested stability reusability, showed five cycles, 10% its performance had lost. role reactive species photocatalysis identified •OH most significant impacts photodegradation. Antibiotic adversely affected presence anions humic acid, but reduction not inorganic anions, only 13%