Sharif Digital Repository

Diffusion flame from electrospray of liquid ethanol and butanol was investigated experimentally. Stable flames were observed at two distinct modes recognized at different flow rates, applied voltages, and distances between the nozzle and counter electrode. The first mode occurred at minimum voltages in which individual larger droplets are dominantly generated. The second mode at higher voltages corresponds to multijets, which produce finer distribution of droplets. Using flame-imaging anal- ysis, flammability margins are introduced and flame lengths are measured versus nondimensional parameters for both fuels and modes of spraying. The fluctuation of the flames is characterized and the... 

Nickel modified NiOOH electrodes were used for the electrocatalytic oxidation of ethanol in alkaline solutions. The electro-oxidation of ethanol in a 1 mol/L NaOH solution at different concentrations of ethanol was studied by ac impedance spectroscopy. Electrooxidation of ethanol on Ni shows negative resistance on impedance plots. The impedance shows different patterns at different applied anodic potential. The influence of the electrode potential on impedance was studied and a quantitative explanation for the impedance of ethanol oxidation was given by means of a proposed mathematical model. At potentials higher than 0.52 V(vs. Ag/AgCl), a pseudoinductive behavior was observed, but at those... 

One of the key solutions to improve engine performance and reduce exhaust emissions of internal combustion engines is direct injection of bio-fuels. A new modified bio-ethanol is produced to be substituted by fossil fuels in gasoline direct injection engines. The key advantages of modified bio-ethanol fuel as an alternative fuel are higher octane number and oxygen content, a long-chain hydro-carbon fuel, and lower emissions compared to fossil fuels. In the present study spray properties of a modified bio-ethanol and its atomization behaviors have been studied experimentally and theoretically. Based on atomization physics of droplets dimensional analysis has been performed to develop a new... 

Low-cost ethanol vapor sensors are fabricated by electrospinning of TiS2/PVP fibers on pre-patterned metal electrodes. TiS2 ribbons have been synthesized through sulfuration of titanium (Ti) foil using chemical vapor transport (CVT). We found selective and stable responses at a low concentration of ethanol vapor (2 ppm) at room temperature with the transient response and recovery times experimentally around 60 s and 2 s respectively. The relatively high responses of sensors (6800% at 18 ppm) are attributable to the synergy effect of TiS2/PVP composite structure. The mechanism of sensing is discussed based on proton hopping while the sensors exposed to ethanol vapor. © 2019 Wiley-VCH Verlag... 

Distilleries wastewater is an important environmental problem due to its high BOD and COD content, and toxic materials such as phenolic compounds, and low pH. Direct and continuous discharge of this effluent to the soil reduces the quality of soil and destroys agricultural crops. In addition, its discharge to rivers and sea will seriously affect aquatic life. In order to prevent environmental hazards, a number of biological, chemical and physical methods have been introduced for treatment of this wastewater. Chemical and physical methods are based on surface sorption, ion exchange, membrane processes and chemical oxidations. In biological methods, anaerobic processes are more economical than... 

The authors regret to inform that the corresponding author is altered from Hamed Karimi Motaalegh Mahalegi to Amir Mardani with the email address of: Amardani@sharif.edu updated as above. The authors would like to apologise for any inconvenience caused. © 2020 Elsevier Ltd  

The effective parameters such as particle size, temperature, pressure and extraction time on supercritical carbon dioxide extraction of cocoa butter form cocoa seed were studied in order to find the optimum conditions for extraction. Particle size from whole cocoa nibs to one millimeter diameter, extraction temperature from 35°C to 55°C, extraction time from 2 to 8 hours and extraction pressure from 5 to 20 MPa were investigated and optimized. The optimum results (according to the limitation of the apparatus) of 5.2% extraction efficiency, suggests that pure CO2 is not a suitable solvent for extraction of cocoa butter in the investigated range of parameters and therefore the use of a... 

In this study, rhodium-copper alloys of different compositions are electrodeposited on graphite electrode from aqueous solutions. The bulk compositions of these alloys are determined using energy dispersive X-ray analysis and surface morphologies are investigated by scanning electron microscopy. The catalytic performance of these alloys in oxygen reduction reaction (ORR) in alkaline media is investigated by linear sweep voltammetry on rotating disk electrode assembly. The number of electrons transferred per O 2 molecule (n) obtained at different potentials is four indicating full reduction of oxygen to hydroxide ion. It is shown that Rh-Cu alloys are better electrocatalysts than Rh with... 

Due to high surface to volume ratio and tunable band gap, two dimensional (2D) layered materials such as MoS2, is good candidate for gas sensing applications. This research mainly focuses on variation of Density of States (DOS) of MoS2 monolayes caused by ethanol adsorption. The nanosheets are synthesized by liquid exfoliation, and then using Scanning Tunneling Spectroscopy (STS) and Density Functional Theory (DFT), local electronic characteristic such as DOS and band gap in non-vacuum condition are analyzed. The results show that ethanol adsorption enhances DOS and deform orbitals near the valence and conduction bands that increase transport of carriers on the sheet. © 2018 IOP Publishing... 

In this work, a porous and flexible three-dimensional (3D) nickel/gold nanoparticle electrode (NiF/AuNPs) is presented as an efficient electrocatalyst for ethanol oxidation in alkaline media. The 3D nanocomposite electrode consists of interconnected porous nickel foam (NiF) with large pores (500±200 μm diameter) surrounded by interconnected struts (∼100 μm) that are decorated with gold nanoparticles (AuNPs, 37±8 nm) through in-situ electrochemical deposition. The catalytic performance of the 3D electrode was evaluated by different electrochemical methods. An enhancement in the performance (about 253 %) and a remarkable decline in onset potential (about ∼0.63 V) in comparison with pristine... 

We present fabrication, characterization, and experimental results describing electrical actuation and readout of the mechanical vibratory response of electrospun ZnO nanofibers. For a fiber with an approximate radius of 200 nm and a length of 70 ìm, a resonance frequency around 3.62 MHz with a quality factor (Q) of about 235 in air at ambient conditions is observed. It is shown that the measured frequency of the resonance is consistent with results from finite element simulations. Also, the measurements were performed in an enclosed chamber with controlled levels of ethanol vapor. The adsorption of ethanol causes a shift in the resonance frequency of the fibers, which can be related to the... 

In this study, ethanol gas sensing of PVP fiber membranes based on Quartz Crystal Microbalance (QCM) was investigated. The fibers were deposited on the QCM's electrodes by electrospinning the viscous blend solutions of PVP. The effects of PVP concentration on morphology of the fibers and their permeability when exposed to ethanol were investigated. Membranes which were prepared using low concentration solutions, contained beads and high packing fibers and showed low permeability. Increase of the PVP concentration to 12 wt% resulted in continuous fine fibers with good permeability. Furthermore, higher PVP concentrations were found to decrease ethanol permeability due to larger fiber radius... 

A process of ethanol production from wheat straw in Iran was simulated using SuperPro Designer. Wheat is the main cereal crop in Iran. Khuzestan Province was selected as a potential location for the construction of plant. A method was developed to estimate the plant capacity. The base plant size in Khuzestan was estimated to be 316 t day−1. The effect of plant size, logistics of residue collection, wheat yield, and agreements with local farmers on the profitability was calculated, and the minimum selling price was determined for different scenarios. In addition, the sensitivity analysis and economic risk assessment were conducted. The operating cost was mainly sensitive to the wheat straw... 

A process of ethanol production from wheat straw in Iran was simulated using SuperPro Designer. Wheat is the main cereal crop in Iran. Khuzestan Province was selected as a potential location for the construction of plant. A method was developed to estimate the plant capacity. The base plant size in Khuzestan was estimated to be 316 t day−1. The effect of plant size, logistics of residue collection, wheat yield, and agreements with local farmers on the profitability was calculated, and the minimum selling price was determined for different scenarios. In addition, the sensitivity analysis and economic risk assessment were conducted. The operating cost was mainly sensitive to the wheat straw... 

MILD combustion is a promising technique for low heating value fuels. In this paper, spray MILD combustion of diluted liquid fuel is numerically studied. The modelling framework is based on the RANS approach, the EDC combustion model with a skeletal chemical mechanism, and the Lagrangian tracking of droplets. The validated numerical model is used to simulate the combustion of ethanol diluted with water is studied for different oxidizer temperatures and O2 concentrations under MILD condition. Results indicate that a low-level fuel dilution up to 5 percent has tendency toward expansion of MILD region, but higher degrees fuel dilution within the range of 5–20 percent results in a reduction of... 

This paper concerns extending applicability of Dehaghani association equation of state (in short DA-EOS) to model non-ideality in phase behavior caused by hydrogen bonding. Advantageously, this equation only needs two and one parameters to treat self- and cross association, respectively, which were determined for methanol/water and ethanol/water mixture in this study. In this respect, DA was coupled with PR and SRK EOS to account for physical interaction between molecules. Notably, DA-PR persistently provides more accurate prediction than DA-SRK for both aqueous methanol and ethanol solutions  

Mathematic modeling and simulation of a biofilter system was developed for biofilters filled by three different packing materials such as granular activated carbon (GAC), compost mixed with diatomaceous earth (DE), and compost, respectively, and the effects of biofilter length, packing material, biological activity and the operation time of system on the removal of ethanol (influent contaminant) were studied. The mathematical model for analysis of mass transport phenomena in the biofilter was solved using a two-step, explicit finite difference approximation technique and computer simulation was carried out. The obtained results show that at the early stage of biofiltration the dominant... 

Esterification of Phthalic anhydride with 2-Octanol and Sebacic acid with Ethanol has been studied in the presence of Sulfated Titania. This study showed that Sulfated Titania has strong catalytic effect on esterification reactions. The effect of some factors such as reaction temperature, molar ratio of acid to alcohol, amount of catalyst used, reaction time, calcination temperature, drying temperature and calcination atmosphere has been investigated. Equilibrium composition achieved in 80 min for Diethyl Sebacate and 20 min for Dioctyl Phthalate in various conditions. © 2005 Elsevier B.V. All rights reserved  

We studied the effects of the surrounding liquid environment on the size and optical properties of silver nanoparticles prepared by laser ablation by a pulsed Nd:YAG laser operated at 1.064 nm. The silver targets used were kept in acetone, water and ethanol. TEM observations and optical extinction were employed for characterization of particle size, shape and optical properties, respectively. Nano silver in acetone showed a narrow size distribution with a mean size of 5 nm and the colloidal solution was stable. In deionised water a rather narrow size distribution with a mean size of 13 nm was observed and nanoparticles were precipitated slowly after about two weeks. In ethanol, a broadening... 

Purpose. Variable-Temperature Kinetics has been used to obtain the rate constants of the reaction at various temperatures during one kinetic run. Methods. Pseudo-first-order rate constants for the transesterification of procaine with aliphatic alcohols ethanol, n-propanol and tert-butanol were obtained by the fluorescence spectroscopy using the variable-temperature kinetics (VTK) method. Results. The activation parameters of the reactions were calculated (24-28 kcal.mol-1). The half-life of the procaine decreases in the ethanol solution compared with the other alcoholic solutions in the presence of sodium ethoxide. Conclusions. The investigation time of the reactions is reduced to one-tenth...