جستجوی مقالات مرتبط با کلیدواژه "nano photocatalyst" در نشریات گروه "فنی و مهندسی"

Methanol is one of the four basic chemicals that is used beside ethylene, propylene and ammonia to produce other chemicals. Industrial production of methanol is dependent on synthesis gas (a mixture of CO, H2 and CO2). One of the approaches of producing hydrogen from renewable and organic sources is green hydrogen, and researches in this field is being developed as a renewable fuel. Carbon dioxide (CO2) is a greenhouse gas and the main reason of global climate change, which is being studied and recycled to valuable products and fuels. Methanol production is one of method for decreasing CO2. In this study, using an experimental method of nano-photocatalyst and UV light (renewable method), synthesis gas by combining water and hydrocarbons was produced. Experimental results show that with the degradation of 85.3% of hydrocarbons in water, the efficiency of titanium oxide-based copper chromate nano-photocatalyst in the production of synthesized gas is about 14% higher than that of titanium oxide nano-photocatalyst. In addition, the crystalline phase and material structure, morphology and chemical composition were tested and analyzed using the measurements of XRD, SEM/EDS, TEM/EDS and XPS. This catalytic technique can be important in producing a clean fuel due to the reduction of greenhouse gas emissions and environmental effects. One of the applications of methanol in MTBE feed is to increase the octane number of gasoline. It is also proposed, with the reduction of methanol prices in the global market in the future and the growing importance of environmental issues, through appropriate incentives, efforts should be made to invest in the conversion of methanol to propylene.

Petroleum wastewater contains a wide range of hard biodegradable pollutants that are not treated by conventional treatment methods. In this study, the photocatalytic degradation of organic pollutants in the wastewater of Petroleum were investigated using new Fe-ZSM-5@TiO2/Ag synthetic nano-photocatalyst. Synthesis of nano photocatalyst was done by immobilizing iron on zeolite to improve ZSM-5 structure and then TiO2 and Ag coated to reduce the band gap energy. Physical and chemical properties of the materials determined by XRD, SEM, FT-IR and BET analyzes. TiO2 in the anatase phase was shown in synthetic nano-photocatalyst using XRD analysis. The uniformity of the nanoparticles was also revealed in the SEM images, which showed that the TiO2 and Ag particles were well located on the surface of Fe-ZSM-5. Experimental procedure was done using experimental method by response surface method (RSM). The effects of main parameters containing pollutant concentration, photocatalyst nanoparticle concentration, pH, reaction time, radiation wavelength and different photocatalysts were performed in a batch pilot. The results showed that at pH=5 and the photocatalyst concentration of Fe-ZSM-5@TiO2/Ag equal to 2 g/L under UV-A irradiation at 54 watts and 240 min time the best COD removal performance was about 83%.

In this study, the removal and degradation of organic pollutants from real oil refinery effluent was investigated using a synthesized TiO2/Ag photocatalyst fixed on lightweight concrete plates. Petroleum compounds are a set of hydrocarbons some of which are stable, long-term decomposing, poisonous and even carcinogen for human. One of the attractive wastewater treatment techniques is photocatalytic purification and this process has the potential to mineralize all organic and inorganic compounds found in petroleum impregnated processes and convert them into biodegradable and biodegradable compounds. Characterization of synthetic photocatalysts was done using X-Ray Diffraction (XRD) Fourier Transform Infrared Spectroscopy (FT-IR) techniques, Scanning Electron Microscopy (SEM) with EDX analysis, and Nitrogen Adsorption and Desorption (BET). The photocatalytic pilot consisted of three 20×20×5cm lightweight concrete plates coated the nanoparticles on the concrete surface and powered by 36-watt UVA lamps. SEM experiment results showed relatively uniform TiO2/Ag coating on lightweight concrete surface. The synthesized photocatalyst XRD pattern showed the successful synthesis of Ag crystals in the nanocomposite structure. BET results showed that when TiO2/Ag was synthesized, the cavities became mesoporous. Investigation of the effect of pH on the system efficiency in the range of 3 to 12 showed that at pH 4.5, the removal efficiency reached its highest level. The effect of mass loading of TiO2/Ag nanoparticles on the concrete plates showed that the highest removal efficiency in mass loading was 15 gr/m2. To study the rate of COD removal under sun light, the reactor was transferred to the yard in Kharazmi University in Tehran. To obtain results, the experiment was performed three times in both states of using TiO2 and TiO2/Ag under optimum conditions. The rate of COD removal under sunlight for 8 hours and the use of UV-A lamps for TiO2/Ag photocatalysts were 51.8% and 76.3%, respectively. The results showed that the synthetic photocatalyst was capable of treating real wastewater using UV rays.

In this research, Zinc oxide nanoparticles with semi-spherical morphology were synthesized by modified sol-gel method using rosemary extract as a stabilizing agent. The effect of the amount of rosemary extract and calcination temperature on size and shape of the particles was investigated. The samples were characterized by X-ray diffraction (XRD), infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and elemental analysis (EDX). X-ray diffraction results showed hexagonal structure (wurtzite phase) of zinc oxide. According to the SEM results semi-spherical nanoparticles of 18 nm in size were obtained using 75 ml of rosemary extract. The photocatalytic activity of the modified ZnO nanoparticles was investigated for degradation of the methylene blue dye solution. The results showed 96.87% of dye degradation in the 135 min that confirmed suitable efficiency of as-synthesized nanoparticles in the photocatalytic degradation process of dyes.