جستجوی مقالات مرتبط با کلیدواژه « ZIF-8 » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »

In the present work, a polyetherimide/ZIF-8 composite membrane was fabricated by solution casting technique. The prepared membranes were Characterized using Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy – attenuated total reflectance (FTIR-ATR), energy dispersive X-ray (EDAX) and X-ray diffraction (XRD). Furthermore, the membrane's performance in separating carbon dioxide and methane was analyzed through single gas permeability measurements. FTIR-ATR spectrum of the prepared membrane confirmed the functional groups of polyetherimide. XRD analysis showed that the additive was well dispersed in the polymer, resulted in a reduction in the membrane's crystallinity. EDAX analysis confirmed the existence and proper dispersion of Zn particles in the membrane. Finally. The results of permeability tests showed that adding ZIF-8 to the membrane significantly increased its permeability and selectivity. The permeability of the composite membrane for CO2 gas was 5.91 GPU, more than twice that of the pure polyetherimide membrane. Additionally, the permeability for CH4 gas was 0.31 GPU, representing a significant improvement over the pure membrane's permeability of 0.17 GPU. The carbon dioxide/methane selectivity also rose from 15.3 in the pure membrane to 19.1 in the composite membrane. In conclusion, the study demonstrated that adding ZIF-8 to a polyetherimide matrix can improve the effectiveness of the resulting composite membrane for separating CO2 from CH4. The improvement in selectivity was primarily due to the increased solubility coefficient of carbon dioxide compared to methane in the composite membrane.

In this study, ZIF-67 was synthesized through solvothermal method to remove Cr(VI) ions from aqueous solution. To improve the structural properties of ZIF-67 and its adsorption capacity, optimization of the synthesis conditions was carried out based on maximum Cr(VI) uptake. From experiments, the optimum condition was revealed as solvent: metal ion molar ratio of 4.6:1, ligand: metal ion molar ratio of 318:1 and temperature of 23℃. The physio-chemical properties of as-synthesized ZIF-67 were investigated by BET, XRD, FTIR and FESEM analyses. Effect of adsorption pH, adsorbent dosage, initial concentration and contact time on adsorption process was investigated. Based on the results, the maximum adsorption capacity of Cr(VI) was 26.27 mg/g which was obtained at 35℃, pH= 5, adsorbent dosage of 3 g/l and initial concentration of 107.82 mg/l. The equilibrium time for Cr(VI) adsorption varied from 180 min for low initial concentration of 9 mg/L to 240 min for a high initial concentration of 90 mg/L. For the synthesized ZIF-67, maximum uptake capacity was reported 26.27 mg/g at initial concentration of 107.82 mg/l. The equilibrium data were described better by Langmuir-Freundlich isotherm model than the other models at three different temperatures. Pseudo-second-order model fitted the experimental data better than pseudo-first-order one. Adsorption thermodynamics indicated that the adsorption process was endothermic and spontaneous in nature. The regenerability of ZIF-67 was also studied in three sequential cycles and the Cr(VI) adsorption was almost retained after two cycles.