Photocatalytic degradation of amoxicillin, cephalexin, and tetracycline from aqueous solution: comparison of efficiency in the usage of TiO2, ZnO, or GO-Fe3O4 nanoparticles

In this study, effects of a number of parameters such as pH of the solution (3-11), the adsorbent quantity (0.2-4 g L-1), contact time (0-60 min), initial concentration of antibiotics (1-100 mg L-1) and the power of lamp (6 and 18 W) on the removal efficiency of antibiotics with different nano-particles were compared. After carrying out the incumbent experiments and analyses, it was determined that pH adjustment had no effect on the UV/GO-Fe3O4 system efficiency. In one hand, it was indicated that the optimal contact times were achieved at 15, 45, and 45 min and the amounts of catalysts were evaluated at 2, 4, and 4 g L-1 for tetracycline, amoxicillin, and cephalexin, respectively. On the other hand, the optimal conditions in the UV-TiO2/ZnO processes were obtained as the 'catalysts value of 2 g L-1', 'antibiotics concentration of 15 mg L-1', 'radiation intensity of 18 W', 'pH of 5, 7, and 5', 'contact time of 15, 45, and 45 min' for amoxicillin, cephalexin, and tetracycline, respectively. The optimum initial concentration for all three antibiotics was 15 mg L-1 and the maximum removal efficiency occurred at 18 W of ultraviolet radiation. In addition, degradation of tetracycline, a complete removal percentage was achieved for all mentioned catalysts, however, considering amoxicillin and cephalexin, the obtained values were variable and making use of GO-Fe3O4 for amoxicillin and ZnO for tetracycline removal had the maximum removal efficiency ( 87.1% and 81.8%, respectively). Finally, it was noteworthy to mention that a multitudinous of experiments were conducted to determine the most effective catalysts in the photocatalytic degradation of three types of prevalent antibiotics.