Comparing the efficiency of N-doped TiO2 and commercial TiO2 as photo catalysts for amoxicillin and ciprofloxacin photo-degradation under solar irradiation

Advanced oxidation processes (AOPs) have gained traction as alternative solutions for eliminating pollutants from pharmaceutical wastewater for reuse. In this research, the performance of two photo-catalysts (Commercial TiO2 and synthesis N-doped TiO2) were compared in terms of the degradation of amoxicillin and ciprofloxacin from an aqueous solution using a photo-catalytic batch system under solar irradiation. The influence of five operating factors is: pH (5-11), H2O2 concentrations (200-600) mg/L, catalyst concentrations (25-100 mg/L), Antibiotic concentration (25-100) mg/L and reaction time (30-120 min), on the oxidation of the listed above pollutants were investigated using the central composite design (CCD) of response surface methodology (RSM). The catalyst of N-doping TiO2 was synthesized by sol-gel method, using the urea (CH4N2O) as a nitrogen source. The resulting material was analyzed using Scanning Electron Microscopy (SEM), X-Ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Additionally, it can be observed from the analysis of the characteristics of N-doped TiO2 the homogenous dispersion of nitrogen molecules, small particle sizes, and energy-gap reduction, prompting a 6% increase in antibiotic degradation compared with Com. TiO2. In the RSM analysis, the ideal conditions were found to be a pH of 5, H2O2 conc. of 400 mg/L, catalyst conc. of 50 mg, and antibiotics conc. of 25 mg/L for an antibiotics reduction rate of 89.31% (AMOX/Com. TiO2/Solar), 90.2 (CFX/Com. TiO2/Solar), 95.8% (AMOX/N-TiO2/Solar) and 97.3% (CFX/N-TiO2/Solar). Experimental results were in good agreement with predictions because the predicted R-2 matched well with the adjusted R-2.