|
چکیده
|
Isomorphous substitution of Zn-Y zeolite (Zn-DYZ) was successfully conducted with diferent Zn/Al ratios of 0.5:9.5, 1:9, 1.5:8.5, and 2:8 mol ratios (hereafter designed as Zn-DZY-1, Zn-DZY-2, Zn-DZY-3, and Zn-DZY-4, respectively) by the hydrothermal synthesis method. Spectroscopic studies indicate that Zn is decorated into the zeolite framework. The insertion of Zn instead of Al in the zeolite framework in small amounts (0.5:9.5, 1:9 mol ratios of Zn/Al) does not afect the zeolite framework. However, at high Zn loading (mainly Zn-DZY-4, 2:8 mol ratio), the zeolite structure collapse due to the imbalance in electrical charge, as confrmed by XRD analysis. In addition, by increasing the loading of Zn, the deviation of d-spacing and shift in the peak position of the XRD pattern occurs, which is related to the radius of zinc ion compared to aluminum, thus causing the lattice expansion. A signifcant increase in BET surface area and pore volume was observed in Zn-DZY toward NaY (870 toward 906.5 and 0.37 cm 3 g −1 towards 0.392 cm 3 g −1 , respectively), which may be related to the expansion of the zeolite framework because of the replacement of Zn instead to that of Al. These results confrm by XPS data. The XPS results show two diferent chemical environments are related to Al-O-Zn and Si–O-Zn with bit shifts. In addition, the peak position is higher than toward ZnO which is a signifcant reason for the formation of ZnO4 2−in the zeolite framework. The photocatalytic activity of the related catalysts is investigated in the removal of methyl orange. The efect of several parameters including catalyst loading, pH, dye contamination, and zinc loading was studied in the photodegradation process. The best results were obtained in the presence of 32 ppm methyl orange, 70 mg catalyst, pH = 7, and 1:9 Zn/Al ratio under UV irradiation. It was found that the photodegradation kinetics follows pseudo-frst-order kinetics. COD experiment was used to measure the mineralization of methyl or
|