The photocatalytic activity of nano-Bi2O3 was evaluated in degradation of rhodamine B (RhB) as a model of dye pollutant from waste waters. Nano sized Bi2O3 was synthesized using the chemical precipitation method. The as-prepared sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FT-IR). Structural analysis revealed that Bi2O3 contains a unique well-crystallized phase and the average crystallite size of 22.4 nm. The SEM analysis revealed that the size of Bi2O3 particles was mainly in the range of 16-22 nm. Response surface methodology was applied to design experiments and to optimize the photocatalytic process. A second order model was developed and a good correlation was found between experimental and predicted responses, confirming the reliability of the model. The optimal condition for maximum degradation of values of RhB resulted in initial concentration, irradiation time, initial pH and catalyst dosage of 12.5 mg.L-1, 120 min, 4.6-7 and 0. 75 g.L-1, respectively. The Bi2O3 nanoparticles exhibited an efficient ultraviolet photocatalytic activity so that under optimal condition more than 95% of Rhodamine B was decolorized. The Pareto analysis indicated that the order of relative importance of the input variables on the dye degradation efficiency is as follows: Bi2O3 dosage > pH ≈ irradiation time >initial concentration of the RhB. تفاصيل المقالة

The wet peroxide oxidation (CWPO) of phenol in the polluted water on Mg-Al nano mixed oxide was investigated and the optimization and kinetic of the process were studied. The nanocatalyst was characterized by XRD, FESEM, EDS and BET. The average crystallite size of 25 nm was estimated using Scherrer formula.FESEM images approved the catalyst comprised of spherical nanoparticles in the range of 94-130 nm. BET results indicated the mesoporous nanocatalyst (dpore=21 nm) has a specific surface area of 86.3 m2.g-1. The optimized conditions of the process resulted at initial concentration of phenol, reaction temperature, reaction time and hydrogen peroxide volume of 100 ppm, 60ºC, 55 min and 3 mL, respectively. The phenol degradation under the optimal conditions reached 85%. The result of the kinetic study indicated that the oxidation of phenol over Mg-Al nano mixed oxide follows the pseudo-first-order kinetics with a correlation factor of 0.94. The activation energy of phenol oxidation over the catalyst was determined to be 19.07 kJ.mol-1. The Mg-Al mixed oxide is a cheap and green catalyst and could be prove to promising for the CWPO process. تفاصيل المقالة

This study focuses on the application of nanostructured Mg-Al layered double hydroxide as a promising adsorbent in desulfurization of dibenzothiophene, an aromatic sulfur bearing compound from gasoil model. The Mg-Al LDH was synthesized by a co-precipitation method and characterized by FT-IR, XRD, EDX and SEM. The XRD and FT-IR approved the layered structure and crystalline form of the adsorbent, the EDX showed the material content in synthesized adsorbent and SEM approved the nanostructure of the synthesized LDH. Four factors were selected as effective factors of desulfurization process. The optimum state of the factors, including calcination temperature of Mg-Al LDH, dibenzothiophene concentration, adsorbent amount and treatment times selected as the 600 ˚C, 50 ppm, 0.1 mg and 120 min, respectively and the highest desulfurization percentage reached to 73.24%. تفاصيل المقالة

BiFeO3 (BFO), Bi0.86Sm0.07Eu0.07FeO3 (BSEFO), and Bi0.86Sm0.07Cd0.07FeO3 (BSCFO) nano powders were prepared by the sol-gel combustion method and the catalytic performances were evaluated in the acetylation reaction of benzyl alcohol. The physical chemical properties of the catalysts were characterized by using XRD, FT-IR, scanning electron microscope (SEM), EDX and BET surface. The efficient acetylation of benzyl alcohol was carried ‌out over all the nano powders using acetyl chloride/ acetonitrile at room temperature. Among the nano powders, BSCFO showed the highest catalytic performance and the yield of benzyl acetate was 89, 45, and 69 percent over BSCFO, BFO, and BSEFO, respectively. Partial substitution of Sm-Eu and Sm-Cd in bismuth ferrite improved the catalytic performance and increased the specific surface area of the catalysts. A direct relationship resulted between the catalytic performance and the specific surface of catalysts, where BSCFO with the highest surface area (11.7m2/g) exhibited the superior catalytic performance. The quantitative yield for the acetate product also resulted for the acetylation of p-methyl benzyl alcohol, p-nitro benzyl alcohol and p-chloro benzyl alcohol on BSCFO. The catalysts showed good reusability in the process. The study confirmed that the catalysts could be promising for the acetylation of alcohols. تفاصيل المقالة

LaMnO3 and LaMnO3/ZSM-5 nano catalysts were synthesized by Pechini method and their physical-chemical properties were characterized using XRD, FTIR, SEM-EDX, UV-vis DRS, BET surface area and TPR. The correlation between characteristic properties and activity of catalysts were investigated. The catalytic performance of the catalysts was evaluated in combustion of 2-propanol and compared with 1% Pt/Al2O3 performance. The results of SEM and UV-Vis DRS of LaMnO3/ZSM-5 indicated the well dispersion of the perovskite oxide on the support. The results of TPR indicated no direct correlation between the activity and reducibility of the catalysts. The catalytic studies revealed that the supporting of LaMnO3 increased the conversion rate of 2-propanol, which is ascribed to higher surface area, more availability of catalytic sites to probe molecules. In addition, the stability of LaMnO3/ZSM-5 was higher than that of LaMnO3 during a 10 h time on stream. The conversion rate of 2-propanol on the LaMnO3/ZSM-5 was higher even than that on the industrial 1%Pt/Al2O3 catalyst. The study showed that the perovskite/zeolite catalyst could be promising catalysts in the removal of VOCs. تفاصيل المقالة

The catalytic performance of Ni-Al, Mg-Al, and Co-Ni LDHs as novel nanocatalysts was evaluated in the oxidation of toluene. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The XRD and FTIR approved the structure and functional groups of the LDH, respectively. Also, the presence of cations with different oxidation state confirmed by XRD. According to this result, Mars Van Krevelen (MVK) mechanism was suggested for the combustion of toluene over the LDH nanocatalysts. The SEM results indicated that the nanostructure and layered morphology of the catalysts. All LDHs exhibited catalytic activity for toluene oxidation. T80 (temperature for 80% conversion for toluene) for Co-Ni, Ni-Al and Mg-Al LDH catalysts were 225, 277 and 350 °C, respectively. So, the Co-Ni LDH showed the highest activity. Furthermore, Ni-Al LDH exhibited the highest thermal stability. So, we concluded that Ni-Al LDH is a superior catalyst for toluene oxidation in the studied series. تفاصيل المقالة