تحضير ووصف وتطبيق أوكسيد الخارصين لمعالجة صبغة المثيل الأخضر

Preparation, Characterization and Application of Zinc Oxide for Treatment of Methyl Green Dye

This work consists of three parts, the first one is focused on the preparation of ZnO and calcination at 500 OC. Moreover, metallized commercial and prepared ZnO by different amounts of Co and Ag were prepared by photo deposition method.

The properties of naked and metalized commercial and prepared ZnO were estimated by Fourier transform infrared (FT-IR) analysis, X-ray diffraction (XRD) analysis and Atomic force microscope (AFM) analysis. Moreover, the Atomic absorption (A.A) analysis for metalized commercial and prepared ZnO was done.

FT-IR analysis for prepared ZnO was obtained by stretching vibrations of the OH at 3446 cm^-1 and a strong band around 500 cm-1 that assigned to find the stretching band of Zn-O. So these results refer to the creation of ZnO.

The new band around 1383-1384 cm^-1 occurred when cobalt was loaded on commercial and prepared ZnO surfaces. From the other hand, the new band around (1386-1388) cm^-1 was formed when silver was loaded on both commercial and prepared ZnO surfaces.

XRD data was utilized to calculate the mean crystallite sizes and crystallite sizes of naked and metalized commercial and the prepared ZnO by employing the Scherer equation and the modified Scherer equation.

The mean crystallite sizes and crystallite sizes for naked commercial ZnO were increased when loading 0.5%Co and decreased when loading 2%Ag. However, the mean crystallite sizes and crystallite sizes data for naked prepared ZnO were increased with loading 1%Co and 2%Ag.

The AFM images indicated that most of the shapes of naked and metalized commercial and prepared ZnO were semi spherical. Moreover, the most particle sizes were less than the mean crystalline size and crystalline size.

The second part includes studying the effect of different parameters on photo decolourization of methyl green dye with the presence of naked and metalized commercial of ZnO. The parameters involved with the amount and the type of loading metals, dose of catalyst, concentration of dye, initial pH of solution and temperature. However, the third part includes the same parameters studied in the second part but the catalyst is different (naked and metalized prepared ZnO that calcination at 500 oC ).

The photo catalytic decolourization of methyl green in the presence of the naked and the metalized commercial ZnO included decolourization process of it at  ptimum conditions.

The effect of initial concentration of methyl green was studied by employing different concentrations from (25-100) ppm. The reaction is obeyed a pseudo first order.

The dosage of naked and metalized commercial ZnO is determined and the optimum value is equal to 0.7 g/200 mL. on the other hand, the optimum dosage for prepared ZnO is equal to 0.6 g/200 mL, while the value is slightly increased with loading of 2%Ag on prepared ZnO surface.

The best initial pH of aqueous solution for photo catalytic decolourization of methyl green is equal to 10 with commercial ZnO and 5.40 for 2% Ag /commercial ZnO, prepared ZnO and 2% Ag /prepared ZnO respectively.

The effect of temperature was investigated by utilizing Arrhenius equation and found it is the rise in the temperature of (278.15 to 293.15) K was increased the rate of reaction, hence the photo-decolourization of methyl green was endothermic reaction. Moreover, the activation energy found to be (24.910) kJ/mol with the presence of commercial ZnO, while it is equal to (6.185) kJ/mol with the presence of Ag (2.00)/ commercial ZnO and equal to (19.690, 10.375) kJ/mol with presence of prepared ZnO and Ag (2.00)/prepared ZnO respectively. The change in entropy was found to be fewer, which that indicated an increase of randomness, while the reaction was non spontaneous.