Sharif Digital Repository

The aim of this study is to mimic water oxidizing complex to find new materials and also to understand their rules in this matter. To achieve this, manganese complexes containing 2,4,6-tris (2-pyridyl)-1,3,5-Triazine, 1,10-phenanthroline, 1,10-bipyridine, Schiff base, amino acids, 2,6-pyridinedicarboxylic acid, 2-pyridinecarboxylic acid have been synthesized and characterized by elemental analysis, IR, EPR, ESI-MS, electronic absorption spectroscopy, electrochemistry, X-ray diffraction and oxygen evolution in presence of oxone and Ce(IV). It is shown that the reaction between Mn(II) complexes containing 2,4,6-tris¬(2-pyridyl)-1,3,5-Triazine, 1,10-phenanthroline, 1,10-bipyridine,... 

In this research, the capability of an aerobic moving bed biofilm reactor (MBBR) for removal of phenol from Arak refinery dilute wastewater has been investigated. A cubical MBBR with approximate capacity of 10 liters was filled with Kaldnes-K1 biocarriers at filling ratio at 50 percent. Moreover, The MBBR which filled with actual refinery wastewater, combined with Flocculation and Coagulation in order to removing more COD, turbidity and TSS and also reaching to criterion that water can be used by cooling tower. The effects of Phenol concentration (10-100 mgl-1), COD concentration (50-500 mgl-1), Hydraulic Retention Time (HRT) (4-12 h) and Phenol shocks on the performance of MBBR were... 

Solid oxide fuel cells as high temperature electrochemical devices draw much attention in the last decades due to their fuel flexibility, high efficiency and low pollution. However, lowering operating temperature from about 850°C to around 650°C without significant overpotential loss, in order to lower costs and increase cells life time has remained a challenge. Recently, a new family of mixed ionic and electronic conducting ceramics (MIECs) which are formulated Ln2NiO4+δ (Ln= La,Nd,Pr) and crystallized in Ruddlesden–Popper structure, have been regarded as appropriate cathode materials for the low or intermediate temperature solid oxide fuel cells (IT-SOFC). Amongst these compounds,... 

A microbial fuel cell (MFC) is a bioreactor that utilizes chemical energy in the chemical bonds of organic compounds to electrical energy production through catalytic reactions of microorganisms under anaerobic conditions. In this study, the performance of a dual chamber, mediator-less anode, graphite electrodes MFC employing mixed consortia as anodic inoculums and using a combination of formalin and glucose as substrate was investigated. Different MFCs with different concentration of formalin and fixed concentration of glucose was operated to elucidate the difference in power generation and removal of formalin as an industrial pollutant under similar operating conditions [ambient pressure;... 

Greywater accounts for about 70% of household consumption and can be returned to the consumption cycle if a sustainable system is built in residential areas and the treated water can be used for irrigation, flash tank filling, and even aquifer fillings. The purpose of this study was to establish a sustainable method in small treatment plants that could sufficiently recover the water used in households. In this study, chemical ways of wastewater treatment, as well as membrane filtrations, were investigated to reduce greywater pollution. The results show that the coagulants alone can remove 80% of COD. Membranes can also reduce COD by up to 83%. In addition, the best removal efficiency using... 

Electrochemical water splitting which consists of two half-reactions, namely; the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), is an important process in electrochemical energy storage and sustainable production of energy. Therefore, the development of cost-effective and efficient electrocatalysts for water splitting has attracted a lot of interest. In this work, a new nanocomposite was prepared from cobalt diselenide and cerium (IV) oxide derived from calcination of a cerium-based metal-organic framework (Ce-MOF), via hydrothermal and electrodeposition methods. The structure and morphology of synthesized materials were investigated by XRD, FE-SEM, EDX, and BET... 

In this study, the use of a fixed bed of the Kaldnes commercial carrier in the activated sludge system has been investigated. In this way, at zero time, a submerged fixed bed of Kaldnes was placed into a completely mixed activated sludge reactor and its various parameters were investigated during the time. During the experiment, the fixed bed (Kaldnes carriers enclosed in a lace) with 20, 35 and 50 percentage of volumes were compared to regular activated sludge reactors (without any carriers). The studied parameters are COD, DO, MLSS, and P-PO43-. Input COD was changed at concentrations of 1200 and 400 mg/L, and the reactor hydraulic time was adjusted to 10 and 16 hours. It was observed that... 

The global energy outlook has been altered as a result of mounting concerns regarding fossil fuels. Electrocatalysts have become a favorable alternative for renewable energy production processes, particularly in the fields of hydrogen evolution reactions (HER) and oxygen evolution (OER). This study focuses on the production and enhancement of nanocatalysts, specifically materials based on ZIF-67, for the purpose of water splitting. The initial phase included the synthesis of the ZIF-67 structure through the simple room-temperature coprecipitation process, utilizing cerium as a dual-metal component. The molarity of the cerium was optimized in the ZIF-67 framework to achieve the most desirable... 

MILD combustion can be a promising technology to prevent global warming. In this study, for the first time, the numerical simulation of MILD spray combustion of kerosene fuel with preheated and diluted air has been conducted in the faculty's SMSTR test stand. The modeling framework is based on the Reynolds averaged Navier-Stokes turbulence approach and the standard k–ε model, the DPM discrete phase model, and the EDC combustion model, using the skeletal chemical mechanism of Jet A POSF10325 kerosene with the air and droplet being tracked in Lagrangian coordinates. The simulation is done in a steady state and by an axisymmetric method, and the effects of inlet oxygen concentration, inlet air... 

Membrane bioreactors (MBRs) which are commonly understood as the combination of membrane filtration and biological treatment using activated sludge have several advantages, but membrane fouling reduces the membrane efficiency, permeability and lifetime. An alternative is replacing a moving bed biofilm reactor (MBBR) with the activated sludge system which may reduce the effect of membrane fouling. The sludge produced in MBBRs has poor settling characteristics, therefore, their efficiency is limited by the sedimentation tank performance and they require a larger settling surface. The combination of moving bed biofilm reactors and membrane bioreactors can compensate for the drawbacks of both of... 

The sluggish kinetics of oxygen evolution and reduction on the surface of electrodes is a major problem for the widespread use of devices that are based on sustainable, renewable and clean technologies, such as fuel cells and metal–air batteries. Therefore, the development of efficient and cost–effective materials for the oxygen evolution (OER: Oxygen Evolution Reaction) and reduction reactions (ORR: Oxygen Reduction Reaction) is highly desirable. In recent years, Metal–organic frameworks (MOFs) and their derivatives, have drawn considerable attention as potential catalysts and electrocatalyst due to their high surface area and porous structure. In this study, cerium (IV) oxide was... 

The sluggish kinetics of oxygen evolution and reduction on the surface of electrodes is a major problem for the widespread use of devices that are based on sustainable, renewable and clean technologies, such as fuel cells and metal–air batteries. Therefore, the development of efficient and cost–effective materials for the oxygen evolution (OER: Oxygen Evolution Reaction) and reduction reactions (ORR: Oxygen Reduction Reaction) is highly desirable. In recent years, Metal–organic frameworks (MOFs) and their derivatives, have drawn considerable attention as potential catalysts and electrocatalyst due to their high surface area and porous structure. In this study, cerium (IV) oxide was... 

Prevent shrinkage and porosity in the melting parts expensive attention has been cast as a piece of low cost healthy and free from defects in casting production. Calculated feeding distance and the required number of risers. Also ensure that more tests were done with computer simulation compared the results acceptable to have the cast and expensive to produce a piece has nearly no troubleshooting. Variety of factors can affect the riser effect is melting parts Read some of these factors include alloy melting, superheat and mold .... . Oxygen factor in the project as one of the molten factors between feeding distance for molten plain carbon steel melting components and parts reviews and... 

In order to obtain more insight into the enzymatic oxygen-atom-transfer (OAT) process and elucidate the relation between the structure and function of the synthetic model complexes, new molybdenum and tungsten complexes containing different chelating ligands were systematically prepared and investigated. Herein, the cis-dioxo-molybdenum(VI) complexes with new aromatic dithiolene ligands, formulated as [MoO2(2,3ppdt)2]NR4 and [MoO2(3,4ppdt)2]NR4, (2,3ppdt= pyrido-2,3-pyrazine-2,3-dithiolato, 3,4ppdt= pyrido-3,4-pyrazine-2,3-dithiol and R= Et or Bu) were prepared and investigated by elemental analysis, IR, 1H NMR and UV-Vis spectroscopic methods. An OAT reaction of [MoO2(2,3ppdt)2]2– with PPh3... 

In this project, BiVO4 , Mn3O4 and BiVO4- Mn3O4 nanocatalysts were synthesized using the hydrothermal method. The properties of these nanocatalysts were determined by XRD, SEM, FT-IR, DRS, PL, ICP, EDX, BET and AA techniques. Analysys XRD patterns and SEM images of samples confirmed monoclinic structure for BiVO4 and tetragonal structure for Mn3O4. The DRS and PL spectra showed adctrease in the band gap and electron – hole pair recombination for BM 60:40 relative to BiVO4. Oxygen production was studied in the presence of different percentages of BiVO4 and Mn3O4 in BiVO4 - Mn3O4 nanocomposite and was observed that the 60:40 wt.% (Bismuth vanadate 60% and manganese oxide 40%) produced more... 

Today, fossil fuels cause countless environmental pollutants, so replacing fossil fuels with clean energy sources is very important. Water splitting using light and a semiconductor is one of the new methods of producing oxygen and hydrogen, which due to its simplicity and cheapness, has attracted a lot of attention today. In this study, ZnMn2O4 photocatalyst nanoparticles were first loaded on a graphitic carbon nitride support in different ratios of ZnMn2O4 and carbon support by hydrothermal method. Then the photocatalysts were evaluated for evolution of oxygen and hydrogen photocatalysts through water splitting under visible light. In ZnMn2O4 / g-C3N4 (80:20) nanocomposite, the highest... 

Lead-acid batteries have been used for over 150 years as a reliable means of storing electrical energy. These batteries have a variety of applications due to their high safety, reliable performance, and relatively easy manufacturing process, including in car starters, car lighting and combustion, electric vehicles (especially electric bicycles), and the resulting electrical energy storage. From renewable sources or pulsed power supplies in hybrid electric vehicles. Despite increasing advances in the performance and design of these batteries, there are still problems in this area. One of the most important of these is the electrolysis of water as a side reaction, which leads to the production... 

The enormous benefits of hydrometallurgical processes have led to the progressive metals extraction industry. Many studies are carried out on the application of these processes in the copper extraction industry. In this research, the oxygen pressure leaching of chalcopyrite concentrate was studied. Experiments were carried out under conditions of the solid-liquid ratio of 0.1, agitation speed of 750 rpm, and sulfuric acid concentration of 2M in a stainless-steel autoclave system. Central composite design (CCD) was used to design experiments, and three factors of temperature, time, and pressure of oxygen, were selected as design variables. The obtained model for %Cu includes parameters of... 

A bioreactor can refer to any device or system constructed on engineering basis and has an active biological medium. This medium includes aerobic and non-aerobic reactions in which organisms and the theire produced substances have the main role. One of the applications of bioreactors is to provide an appropriate medium for animal and plant cell culture and growth. Nowadays many biological processes in high volume scales are carried out in stirred tank bioreactors. In these bioreactors oxygen transfer is usually increased by increasing turbulence which is necessary for mixing nutrients and keeping the homogeneity of the medium. However, there are some limitations for increasing the stirring... 

Development of novel photosensitizers and photocatalysts with near-infrared (NIR) light activity and efficient sunlight harvesting is of great importance in photodynamic therapy and environmental remediation. In this work, very small (20 nm) upconverter SrF2:Yb,Tm@CaF2:Yb@Fluorine-doped TiO2 heteronanoparticles (denoted as UCNPs@TiO2) with strong UV-blue emission and wide-spectrum photocatalytic activity were synthesized via a facile three-step hydrothermal method, for the first time. The SrF2: Yb,Tm upconverter nanoparticles were produced as the light-emitting core, epitaxially-grown CaF2 : Yb as the middle shell to enhance the Upconversion luminescence efficiency and TiO2 as the...