امین عبادی

Antibiotics are a group of emerging contaminants in the aquatic environment that due to cumulative effects, different adverse effects, and leading to drug resistance, residues threaten the human health and ecosystem in the low concentrations found in the environment. This makes it necessary to provide wastewater treatment facilities in the production sources of these materials to prevent their unnecessary release into the environment. Therefore, the purpose of this study was to determine and catalytic analysis of the antibiotic metronidazole by using iron nanoparticles supported on the synthesized graphene in aqueous solutions.

In the present experimental study conducted in 2023, graphene-supported iron nanocomposites were synthesized using green chemistry method and pomegranate juice as a reducing agent. The physical and structural characteristics of the synthesized adsorbent were analyzed by XRD, SEM and TEM techniques. In this study, the effect of variables such as solution pH (3, 5, 7, 9 and 11), adsorbent dose (10, 30, 50, 70, 90 and 100 mg), initial concentration (5, 10, 25, 50, 75 and 100 mg/L), contact time (15, 30, 45, 60, 75 and 90 min) and reaction temperature (5, 15, 25, 35, 45 and 55 °C) in the removal of metronidazole antibiotic under the process of surface absorption by Fe/Graphene nano-absorbents were studied. A spectrophotometer was used to measure the residual concentration of metronidazole antibiotic at the wavelength of maximum absorption (320 nm). The collected data were analyzed using statistical tests of analysis of variance.

The Scanning Electron Microscope (SEM) image indicated that the particle size of the catalyst sample was in the range of 40-60 nm. Moreover, the practically spherical shape of catalyst nanoparticles was revealed from the image. The results of the present study indicated that at the optimal pH 5, the highest removal efficiency of metronidazole was obtained in the presence of 5% iron nanoparticles supported on the graphene. Whit a 60-minute contact time and 50 mg/L initial concentration of metronidazole, the removal efficiency was 92%. The optimal and economical dose of catalyst was also obtained at 0.1 g and reaction temperature was 45 °C.

The results indicated that the catalytic process of iron nanoparticles supported on the graphene can be an efficient process in the field of removing the antibiotic metronidazole from aqueous solutions and due to the simplicity of its separation by an external magnetic field, therefore it can be considered a suitable substitute for other catalysts.

In this study, zinc titanite nanoparticles were synthesized using the solvothermal method. The effects of pH and calcination temperature on the structures, morphology and photocatalytic activity of the resulting compounds were investigated.These nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), emission reflectance spectroscopy (DRS), X-ray energy dispersive spectroscopy (EDAX), Photoluminescence (PL) and UV-Vis spectroscopy.X-ray diffraction patterns confirmed the cubic pure ZnTiO3 structures synthesized at pH= 3 and calcination temperature of 700 ° C and hexagonal at pH=3 and pH=7 and calcination temperature of 800 ° C. Crystallinity was not visible in scanning electron microscope images. Also, full cubic and hexagonal structures of ZnTiO3 nanoparticles are easily visible in transmission electron microscopy images. In investigation photocatalytic results, Photocatalytic degradation kinetics data were evaluated by pseudo-first-order kinetics model. The efficiency of methylene blue dye degradation under visible light of the catalysts ZTO-10-900, ZTO-7-800, ZTO-3-700 was 95%, 83% and 78%, respectively. In ZTO-10-900 catalyst the presence of 423 and 527 nm bands in the photoluminescence emission spectra indicates the presence of crystalline defects in this compound and the major factor contributing to the higher efficiency in photocatalytic activity.