Sharif Digital Repository

The aim of the present study was to evaluate the photocatalytic degradation of anthracene using Fe-doped TiO2 nanoparticles in the presence of UV. The structure and morphology of Fe-doped TiO2 nanoparticles were studied by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The applied nanoparticles were synthesized by the sol–gel method. The effect of influential parameters on the degradation of anthracene, including pH, time, nanopar-ticles dosage, and the concentration of anthracene was studied. Using the UV/Fe-doped TiO2 system, the optimum experimental values were obtained to be as follows: pH = 7, contact time = 60 min, anthracene concentration =... 

This study concentrates on the industrial waste materials which have pozzolanic and / or cementitious property and can possibly be used in concrete mixtures or in controlled low strength material (CLSM) mixes. These materials as a cementitious or pozzolan not only reserve the environment but can replace Portland cement or reduce it. As in production of one tonne of Portland cement about one tonne of carbon dioxide is released into the environment, the aim is to reduce the amount of the Portland cement use in construction materials as much as technically possible. The research shows that some of the industrial waste materials or by-product materials which are produced in a vast amount per... 

The increase of pollution and the expansion of industrial, agricultural wastewater and urban runoff discharges in water sources have intensified the concentration of water pollutants. Considering that in Iran as in other countries the major part of drinking water is obtained from surface waters and due to the importance of disinfection, chlorination is doubtlessly the optimum and most common water treatment method used. However this method produces chlorination by-products (CBPs). Trihalomethanes(THMs) and Haloaceticacids (HAAs) are the main and most important groups of disinfection by-products (DBPs). Separation of THMs has gained a lot of breakthroughs since a lot of time elapses from its... 

The results of three cases of two consecutive reactors are studied in two types of co-current and counter-current flow in second reactor where two consecutive reactors are oxidative coupling of methane (OCM) and Fischer-Tropsch (FT) reactors. FT reactor can be fixed bed or membrane fixed bed reactor with a hydrogen perm-selective membrane. Effect of CH4/O2 ratio, contact time, inlet temperature, and amount of N2 in OCM feed on C2 to C5+ hydrocarbons produced in FT reactor were studied. Results show that use of counter-current hydrogen-perm selective membrane FT reactor that sequenced after OCM reactor improves the C5+ yield as a desirable product and reduces the amount of CH4 and CO2 as... 

In this paper, the effects of two methods of iridium impregnation into HZSM-5 on catalyst stability, selectivity for propylene and byproducts in the conversion of methanol to propylene (MTP) were investigated in a continuous flow isotherm fixed-bed reactor. XRD, BET surface area, NH 3-TPD and ICP-AES analytical techniques were applied to define the physical and chemical characteristics of zeolites. The reaction was conducted at 480°C and 1 bar with WHSV = 1 h -1, and with an equal weight percent of methanol and water in the feed. The results revealed that iridium impregnation into HZSM-5 powder led to enhanced propylene selectivity (8%) and catalyst stability while iridium impregnation into... 

Na3MnCO3PO4 (NMCP) particles were synthesized via ball milling of Mn(NO3)2.4H2O, Na2HPO4.2H2O and Na2CO3.H2O powders. The particles were anchored onto reduced graphene oxide (rGO) sheets during hydrothermal reduction process under stirring. Materials produced were characterized by x-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), thermogravimetric (TG) measurement and galvanostatic charge/discharge tests. Results showed that dissolution of ball milling products in DI water is an effective method for separation of NMCP from byproducts. Best milling time for production of pure NMCP of minimum particle... 

We present the first density functional theory study on α-ketoglutarate dependent halogenase and focus on the mechanism starting from the iron(IV)-oxo species. The studies show that the high-valent iron(IV)-oxo species reacts with substrates via an initial and rate determining hydrogen abstraction that is characterized by a large kinetic isotope effect (KIE) of 26.7 leading to a radical intermediate. This KIE value is in good agreement with experimental data. The reaction proceeds via two-state reactivity patterns on competing quintet and septet spin state surfaces with close lying hydrogen abstraction barriers. However the septet spin radical intermediate gives very high barriers for...