Based on the necessity of protecting the environment and the defined goal of this thesis, this research was conducted for the photocatalytic removal of aqueous solution of cephalexin antibiotic. In the first step, a series of two-components of iron doped with titanium dioxide composites, Fe-TiO2, and three components of iron doped with titanium dioxide and Mxene composites, Fe-TiO2/Ti3C2, were designed and synthesized by sol-gel technology. In order the synthetic composites have the maximum photocatalytic activity in elimination of cephalexin drug in aqueous solution, the ratio of its components were optimized. The optimal composition percentages of trivalent iron in the two-components composite as well as Mxene in the three-components composite was obtained by screening method and using the initial tests of the cephalexin degradation process under a certain operating condition (cephalexin concentration: 10 mg/L, nanocatalyst concentration: 1 g/L, initial pH of the solution: 4.5 and the irradiation time: 120 minutes). The optimal weight percentages of 5 were obtained for the both trivalent iron components and Mxene Ti3C2. By using the optimal three-component composite, Fe-TiO2, FeTiO2/Ti3C2 composite Cephalexin degradation rate was 28% and 12.8% respectively. Considering the decrease in the rate of destruction by using the optimal three-component composite compared to the optimal two-component composite, the performance of the optimal three-component composite was investigated in the photocatalytic degradation of Direct Red 16 dye, and under the same operating conditions as cephalexin the degradation rate was 69.2%. By comparing the efficiencies of the optimal ternary composite in the degradation of cephalexin and DR16 dye, it was determined that this nanocatalyst is not efficient for the photocatalytic reduction of cephalexin. In the next step, in order to prepare an effective catalyst for cephalexin degradation, bismuth oxide was used due to its low energy gap and high absorption ability in visible light, and a set of three-components Fe-TiO2/Bi2O3 composites were synthesized by sol-gel technology and similar to the two previously mentioned catalysts, the ratios of its components were optimized. The optimal weight ratios of Fe3+/Ti4+ and Bi2O3/TiO2 components were founded 3 and 11%, respectively. The amount of cephalexin degradation using this catalyst, under operating conditions (cephalexin concentration: 10 mg/L, catalyst concentration: 1 g/L, initial solution pH: 4.5, and irradiation time: 240 minutes), was 54.2%. The characterization analyzes of FTIR, XRD, DRS, FE-SEM and EDX for 5wt% Fe-TiO2, Fe-TiO2/Ti3C2 and Fe-TiO2/Bi2O3 composites were performed. In order to eva‎luate the effects of various operating conditions (catalyst concentration, cephalexin concentration and initial solution pH) on the photocatalytic degradation rate of cephalexin, experimental design was performed by response surface method for the optimal Fe-TiO2/Bi2O3 catalyst. By using visible light rays (LED lamp with power 50 W and wavelength 395-400 nm), the maximum cephalexin degradation rate was 73.4% under optimal operating conditions (cephalexin concentration: 5 mg/L, nanocatalyst concentration: 1.5 g/L, initial solution pH: 9 and the irradiation time: 240 minute). All experiments were performed at ambient temperature (25 degrees Celsius). By implementing ultraviolet radiation (15W) and Fe-TiO2/Bi2O3 catalyst, under the optimal operating conditions, degradation efficiency of the cephalexin was increased to 96%.

ارجمند مهرباني زين آباد

محمد رحمتي

علي اكبر دادخواه , حميد زيلوئي