جستجوی مقالات مرتبط با کلیدواژه « آلاینده » در نشریات گروه « مواد و متالورژی »

Stable photoluminescence is a phenomenon that is excited by irradiating high-energy light (usually ultraviolet light and sometimes beta rays) to a given substance. After the excitation stops, visible light is emitted from the excited electron states. The material will be done for a time that can be evaluated from seconds to several hours.In the present research, in the first stage, the synthesis of SrAl2O4 with stoichiometric percentages was investigated by solid-state reaction method at temperatures of 900, 1100, 1300, and 1500 ℃. Then, Dy2O3 and Y2O3 additives were added to the SrAl2O4 mixture with ratios of 1 to 4% by weight. The crystal structure and network of the SrAl2O4 host were determined by X-ray diffraction (XRD) analysis. The emission intensity of the mentioned factors was investigated by photoluminescence spectrophotometry (PL) with radiation at the wavelength of 237 nm, and the emission obtained in the wavelength range of 500-540 nm in the sample with different additives. Also, Fourier Transform Infrared Spectroscopy (FTIR) of the host composition and optimized samples with additives were also performed. The microstructure of the synthesized particles was examined using a scanning electron microscope (SEM).

To date, a number of methods have been employed to remove paranitrophenol (PNP) as one of the organic pollutants and nitroaromatic compounds from water. In the present study, the PNP removal process was investigated using surface adsorption and synthesizing cyclodextrin-based adsorbents. To this end, beta-cyclodextrin polymer insoluble in water was first obtained in a green way using citric acid as a cross-linking agent with the efficiency of 81.25% at the swelling rate of 166.7 and after structural characterization, it was used in the adsorption experiments. To expand the contact surface area, some bases such as sawdust and alumina were used as the cyclodextrin supports, and the effect of different parameters on their adsorption capacity such as the contact time, pH, PNP initial concentration, temperature, and adsorbent dosage were studied. The experimental data were then fitted to the kinetics models and adsorption isotherms. It was found that for the synthesized adsorbents, the adsorption kinetics followed the pseudo-second-order equation, and the equilibrium data were more consistent with the Freundlich model. The qmax values ​​for β-cyclodextrin-citric acid, β-cyclodextrin-sawdust, and β-cyclodextrin-alumina adsorbents were obtained as 40.98 mg/g, 43.29 mg/g, and 38.46 mg/g, respectively. Finally, the adsorption thermodynamic was investigated and the standard enthalpy, entropy, and Gibbs free energy changes were calculated.