Sharif Digital Repository

In the present work, the roles of inorganic oxide nanoparticles on the extraction efficiency of polyethylene terephthalate-based nanocomposites were extensively studied. Four fiber coatings based on polyethylene terephthalate nanocomposites containing different types of nanoparticles along with a pristine polyethylene terephthalate polymer were conveniently electrospun on stainless steel wires. The applicability of new fiber coatings were examined by headspace-solid phase microextraction of some environmentally important volatile organic compound such as benzene, toluene, ethylbenzene and xylene (BTEX), as model compounds, from aqueous samples. Subsequently, the extracted analytes were... 

It is well known that the displacement efficiency of EOR processes is mainly affected by wettability of porous medium; however, the role of nanoparticles on wettability alteration of pores surfaces remains a topic of debate in the literature. Furthermore, a little is known about how the dispersed silica nanoparticles affect the microscopic/macroscopic recovery efficiency of heavy oils during common immiscible EOR processes such as water flooding. In this study, a series of injection experiments was performed on five-spot glass micromodel which is initially saturated with the heavy oil. Distilled water and dispersed silica nanoparticles in water (DSNW) at different values of weight percent... 

Regarding the importance of rheological properties of water based drilling fluids, the effects of silica nanospheres, multiwall carbon nanotubes (MWCNTs) and two types of their hybrid, i.e. H1 (80 wt.% silica nanosphere/20 wt.% MWCNT) and H2 (50 wt.% silica nanosphere/50 wt.% MWCNT) on the viscosity and density of distilled water were investigated. According to the results, viscosity and density of the nanofluids increased with the concentration, while they were reduced by increasing the temperature. At high concentrations, the least increase in the viscosity of distilled water by adding the nanomaterials is related to H2 (8.2% increase at 1.0 wt.%). Likewise, the optimum operating... 

The biodegradability rates of two different kinds of polyethylene bonded with corn and potato starch are studied in this paper. While it is usual to use soil as the environment for biodegradation, an aerated sludge tank was used in this studywhich offers a richermicrobialmediumand increases the rate of biodegradation. The biodegradability is determined by two ways: first, comparing differences in the weight change of two samples, one placed inside distilled water and the other placed in aerated sludge tank. Second test for biodegradation is by examination of FTIR spectroscopy. Through FTIR spectroscopy, the biodegradability rate and reduction in some of the existing bonds in polymer before... 

Mechanical alloying and sintering were used to fabricate nanostructured Ti6Al4V scaffolds of highly controllable pore geometry and fully interconnected porous network. Elemental powders were milled for different periods of time (10, 20, 30, 40 and 60 h), mixed with 40-60 vol.-% of 200-400 μm cuboidal NaCl, compacted at 500-600 MPa and sintered according to single or double stage heat treatment regimes at 790 and 950°C under vacuum. After sintering, the samples were soaked in distilled water to washout the NaCl. Foamy microstructures were obtained showing well shaped biopores and fragmentary embedded micropores. The shape of initial NaCl was copied into the biopores which had highly... 

Synthesis of dextran-graft-poly(hydroxyethyl methacrylate) gels as a new fluoride biosorbent was considered in this work. For this propose, the Taguchi experimental design method was used for optimizing the synthetic conditions of the gels to reach high level of fluoride absorbency. The effects of three main parameters including concentrations of monomer (hydroxyethyl methacrylate), crosslinking agent (ethylene glycol dimethacrylate), and initiator (ammonium persulfate) on the final properties of the prepared gels were investigated. The proposed mechanism for grafting and chemically crosslinking reactions was proved with equilibrium water absorption, Fourier-transformed infrared, scanning... 

In this study electrical properties of different water liquids at frequency range of 100-2000 Hz are investigated by using the short invasive and non-invasive cylindrical capacitive sensors (CCSs). Operation of the capacitance measurement module for such probes is based on the auto balancing bridge method. Comparison of the measured capacitances and measured resistances for different water liquids shows decrease by increasing the frequency. In another study the dielectric constant of distilled water, mineral water, tap water and salt water are measured. The effects of the frequency on the resistivity, permittivity and conductance of the different water liquids are also investigated  

In this study, a hybrid of silica nanosphere/multiwall carbon nanotube (MWCNT) has been synthesized by wet chemical method at room temperature. The effect of MWCNTs, silica nanospheres and hybrid nanostructures (80% silica nanosphere/20% MWCNT and 50% silica nanosphere/50% MWCNT) on the thermal conductivity of distilled water has been investigated. SDBS was used as the dispersant to stabilize nanomaterials in the aqueous suspension and its concentration was 1.5 times of the concentration of nanomaterials. As results show, by increasing the concentration of nanomaterials, effective thermal conductivity of nanofluids increased. The most and the least enhancement in the effective thermal... 

The present work investigates the thermal performance of a five turn Open Loop Pulsating Heat Pipe (OLPHP). The effects of working fluid namely water and ferrofluid, heat input, ferrofluid concentration, charging ratio, and orientation will be considered. Experimental results show that using ferrofluids can enhance the thermal performance in comparison with the case of distilled water. In addition, applying a magnetic field on the OLPHP charged with ferrofluid reduces its thermal resistance. Variation of the ferrofluid concentration results in different thermal performance of the OLPHP. Best charging ratio for the distilled water and ferrofluid without magnetic field is 60 % in most of the... 

It is well known that the displacement efficiency of EOR processes is mainly affected by wettability of porous medium; however, the role of nanoparticles on wettability alteration of pores surfaces remains a topic of debate in the literature. Furthermore, a little is known about how the dispersed silica nanoparticles affect the microscopic/macroscopic recovery efficiency of heavy oils during common immiscible EOR processes such as water flooding. In this study, a series of injection experiments was performed on five-spot glass micromodel which is initially saturated with the heavy oil. Distilled water and dispersed silica nanoparticles in water (DSNW) at different values of weight percent... 

A new unbreakable solid phase microextraction (SPME) fiber coating based on aniline-silica nanocomposite was electrodeposited on a stainless steel wire. The electropolymerization process was carried out at a constant deposition potential, applied to the corresponding aqueous electrolyte containing aniline and silica nanoparticles. The scanning electron microscopy (SEM) images showed the non-smooth and the porous surface structure of the prepared nanocomposite. The applicability of the new fiber coating was examined by headspace-solid phase microextraction (HS-SPME) of some environmentally important polycyclic aromatic hydrocarbons (PAHs), as model compounds, from aqueous samples.... 

The immiscible process appears to be one of the first feasible methods for the extraction of oil reserves. However, there is a lack of fundamental understanding of how fracture geometrical characteristics control the efficiency of oil recovery in this type of enhanced oil recovery technique. In this article, a series of experiments were conducted whereby the distilled water displaced n-decane in strongly oil wet glass micro-models having different fracture geometries. Breakthrough time, as a function of injected pore volume of distilled water, was measured using image analysis of the provided pictures. It has been observed that when the fractures' length is increased, the breakthrough time... 

Zero discharge desalination process is the most promising technology to prevent salinity and thermal shocks to ecosystem by effluent streams of desalination unit drained into the sea. Pretreatment, solar pond and forced circulation crystallizer are the major steps of one option to provide the purposes of zero discharge desalination process. Reduction of total hardness of wastewater occurs in pretreatment unit and the solar pond is proposed for effluent concentrated brine wastewater of pretreatment unit which seeks production of potable water and concentrated brine. The effluent stream from solar pond is conveyed to one forced circulation evaporator in order to produce salt and distilled... 

Reinforced polydiphenylamine (PDPA) nanocomposite was synthesized by oxidation of diphenylamine in 4molL-1 sulfuric acid solution containing a fixed amount of carbon nanotubes (CNTs) in the presence of cetyltrimethylammonium bromide (CTAB). The surface characteristic of PDPA and PDPA/CNT nanocomposites was investigated using scanning electron microscopy (SEM). The prepared PDPA/CNT nanocomposite was used as an extraction medium for microextraction in packed syringe (MEPS) of selected pesticides from aquatic environment. The effect of CNT doping level and the presence of surfactant on the extraction capability of nanocomposite was investigated and it was revealed that when 4% (w/w) of CNT in... 

The resistance and capacitance values of the water samples are measured by using two different cell probes (length 10 cm and 5 cm) and a measuring module. Measured conductivities for the different water samples are compared where the lowest conductivity is obtained for the distilled water (3.28 μS/cm) and the highest value is for the boiled water 325.91 μS/cm. Using the measured series resistance values, and by knowing the frequency (1 kHz), the imaginary part of permittivity value is also determined. The imaginary part of the permittivity for the distilled water with the long cell probe is about 0.524 × 10 -7 F/m (for the short probe is 0.523 × 10-7 F/m) while for the boiled water sample is... 

In this study design and operation of invasive and non-invasive cylindrical capacitive sensor (CCS) designs for the electrical measurements of water, water solutions, and water mixtures are reported. Operation of the capacitance measurement module for such probes is based on the charge/discharge method. The measured capacitances and resistances for distilled water, mineral water, tap water and salt water samples are reported by using two sensor types and results are compared. The measured capacitance by invasive CCS for distilled water is about 2.28 μF and by non-invasive CCS is 31.40 pF, which shows a big difference for different probes. Such a difference is due to the electrical... 

It is well known that the oil recovery is affected by wettability of porous medium; however, the role of nanoparticles on wettability alteration of medium surfaces has remained a topic of debate in the literature. Furthermore, there is a little information of the way dispersed silica nanoparticles affect the oil recovery efficiency during polymer flooding, especially, when heavy oil is used. In this study, a series of injection experiments were performed in a five-spot glass micromodel after saturation with the heavy oil. Polyacrylamide solution and dispersed silica nanoparticles in polyacrylamide (DSNP) solution were used as injected fluids. The oil recovery as well as fluid distribution in... 

This work concerns with experimentally and analytically investigation of free gravity drainage process in porous media under the influence of ultrasonic wave radiation. Glass beads ranges from 70 to 100 mesh sizes were packed and used in the tests. The working fluids consist of distilled water, kerosene and Doroud and Paidar crude oils as wetting and air as non-wetting phase. The measured oil recovery data along with Hagoort (1984) backward methodology were used to determine and to compare the relative permeability of wetting phases in presence and absence of ultrasonic radiation. In addition the relative permeability of non-wetting phases for both cases were calculated from inverse modeling... 

Platinum nanowires (PtNWs) were electrodeposited on the polycarbonate templates (PCTs) in aqueous solution of H2PtCl6 in triply distilled water. Nanowires with diameters of 50 and 100 nanometers were electrodeposited on the same condition. The kinetics of electrodeposition process was studied by electrochemical techniques such as voltammetry and chronoamperometry methods. Increasing the scan rate, the peaks shifted to more negative potentials and the current density also increased in each peak which was typical for a diffusion-control process. The potential range for the deposition of platinum nanowires was specified and consequently the potentiostatic i-t transients were utilized to produce... 

In the current work, synthesis of an environmental-sensitive superabsorbent hydrogel using γ-rays is described. Grafted polyacrylonitrile onto a homogeneous solution of starch and kappa-Carrageenan hybrid backbones created a smart material with reversible behavior. The reaction parameters (i.e. acrylonitrile, starch and kappa-Carrageenan concentration, as well as γ-irradiation time) affecting the. water absorbency of the. hydrogel were optimized using the. Taguchi method, in order to achieve a hydrogel with high swelling capacity. FTIR spectroscopy was used for confirming the. structure of the final product and the morphology of the synthesized hydrogel was examined by a scanning electron...