جستجوی مقالات مرتبط با کلیدواژه « glycerol » در نشریات گروه « شیمی »

The study's goal is to create a radiator-like device with fixed rectangular duct winglets that circulate glycerol/water fluids with varying concentrations of copper oxide Nanofluids for improved heat transfer and cooling performance under all working situations. Hot water enters the rectangular duct at one end, while the cooling working fluid enters at the other. The findings of the experiment are compared with the computational fluid dynamics model of rectangular duct-winglets for glycerol/water, glycerol/water of 0.1, 0.2, 0.3, and O.4% weight of copper oxide Nanofluids working fluids at a flow rate of 0.1, 0.2, 0.4, and 0.3 liters per minute. The findings demonstrated that the magnetohydrodynamics effect, which is based on the radiation parameter, increased as the flow through a region's heat transfer, causing a higher temperature and pressure drop in the glycerol/water-0.3% weight Copper oxide Nanofluids at 0.3 L/min flow rate. The results of the experimental for glycerol/water with 0.3% wt Copper oxide Nanofluids at 0.3 L/min flow rate showed that the pressure and temperature drop at Reynolds number 5400 were 19.8 kPa and 9.8 °C with its relevant friction factor and Nusselt’s number 0.0113 and 12.97 respectively.

Copper nanoparticles are widely used in various industries and products. Size and morphology are two important parameters to determine nanoparticle properties. In this study, copper nanoparticles were synthesized without an inert environment using two different reducing agents namely ascorbic acid and sodium hypophosphite. Various capping agents (PVP 105, PVP 4×104, PEG 6000, SDS, CTAB and glycerol) were used as stabilizers. Effect of several parameters including reducing agent concentration, type and amount of stabilizer and precursor concentration on the size and stability of the resulting nanoparticles have been investigated. The synthesis experiments resulted in a 25-60 nm average size of nanoparticles based on the synthesis conditions and the stabilizer type and concentration. Also this research provides a fast and simple way for the synthesis of stable pure colloidal copper nanoparticles in polyol, which is accomplished by decreasing CuSO4.5H2O using sodium hypophosphite in glycerol and without inert medium and homogeneous and non-agglomerated, 25 nm copper nanoparticles were obtained. The as synthesized copper nanoparticles are characterized using scanning and transmission electron microscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and dynamic light scattering techniques.

Encapsulation process is employed to preserve flavor from inadmissible interactions with food, minimizing flavor-flavor interactions, guarding in contradiction of light-induced reactions or oxidation, and increasing flavors shelf-life or allowing an organized release. The aim of this study is to define the preparation and benefits of encapsulation of Pistacia khinjuk gum essential oil as a flavor via nanoemulsion process. Nanoemulsion was prepared by sonicating technique with a probe-type ultrasonicator at varying amounts of surfactant and glycerol. The design expert software was used to optimize the size of nanoemulsion. The nanoemulsion was characterized by DLS analysis, and TEM. The antibacterial activity of nanoemulsion and gum essential oil was performed at four different levels (0.01, 0.1, 1, and 10 %) on ten strains of bacteria. The cytotoxicity of gum essential oil and nanoemulsion was also evaluated toward β-TC3, MCF7, and HT29 cell lines.

In the present study the production of biodiesel was performed by using raw material like soybean oil by trans-esterification process. According to the American Society for Testing and Materials (ASTM), the international specification free glycerol in biodiesel should not be more than 0.02 mass %. To achieve the biodiesel with the ASTM specification, biodiesel was separated using prepared PAN ultrafiltration membranes. The polyacronitrile ultra filtration membranes were prepared on supporting material of woven fabric by phase inversion technique of membrane casting. The prepared membranes were characterized in terms of its molecular weight cut off and flux of the membranes. Different molecular weights of the BSA solutions were used to determine the molecular weight cut off of the membranes. Then the obtained 6KDa and 15KDa Ultra filtration PAN membranes were used to separate the glycerol from (FAME) free acid methyl ester. It was observed that the both membranes were separated glycerol from the biodiesel below 0.02 mass % which meets the requirements of the ASTM specification of glycerol. The permeate side of the 6KDa membrane was estimated to be 0.017 mass % of glycerol, whereas, 15 KDa membrane was 0.02 mass % . The glycerol percentage in retained side membranes were increased with time.

Films were prepared using the casting method from enset starch, as a filler material, glycerol & sorbitol as plasticizers at different concentrations (15, 25, and 35%). And glucose, fructose, and sucrose were added to enhance flexibility. The films were characterized and compared with the effect of plasticizer type (glycerol and sorbitol) and the concentration of some physicochemical properties of ES-based films. The films were analyzed for moisture content, film density, and thickness, swelling capacity, tensile strength, and percentage elongation. The study indicated that moisture content, film thickness, film density, swelling capacity, tensile strength, and percentage elongation are dependent on the type of plasticizer and its concentration. Increasing the plasticizer concentration from 15 to 35 % increases moisture content, and film thickness; decreases the film density, water swelling capacity, and tensile strength of films, regardless of the plasticizer type used.

In this study, solubility and tie-line data of ternary system water + glycerol + 1-butanol were determined at 293.2, 298.2, and 303.2 K and atmospheric pressure. This thermodynamic system is relevant for the production and purification of biofuels. Phase equilibrium data have been determined by the cloud-point titration method and the tie-lines were obtained by correlating the refractive index of the binodal curves as a function of mixture composition. All measured LLE data were modeled by UNIQUAC and NRTL activity coefficient equations obtaining a satisfactory accuracy with modeling errors lower than 0.4%. Binary interaction parameters of tested thermodynamic models were estimated to predict the value of tie lines using a hybrid bio-inspired swarm intelligence optimization algorithm, that is, MAKHA without and with closure equation. This hybrid method was reliable to solve the global optimization problem for the binary interaction parameter identification of this ternary system. The results of this paper provide useful information for the design and modeling of industrial units for glycerol recovery, which is a relevant industrial feedstock.

Desilication of natural zeolite by alkali treatment to produce solketal was successfully prepared.  Natural zeolite from Tasikmalaya, West Java, Indonesia, has been used as a catalyst source. The natural zeolite source was mordenite type structure. The experimental condition was varied to study their effect on the catalyst efficiency. Several characterization methods, such as Thermogravimetric Analysis (TGA), Brunauer Emmett Teller (BET), X-ray Diffraction (XRD), Scanning Electron microscopy (SEM), etc., were used to analyze the physicochemical properties of the prepared catalyst. From the temperature-programmed desorption of NH3 (TPD analysis), the acidity of zeolite decreased from 0.597 to 0.444 by increasing NaOH concentration from 0.1 to 0.7 M, respectively.  The result showed that alkali treatment did not change the phase structure of natural zeolite significantly. Here, the ratio of Si/Al decreased by increasing NaOH concentration, resulting in the decrease of acidity value. Interestingly, the efficiency of zeolite catalyst (HZ-01) shows the highest conversion and selectivity at around 98.73% and 74.66%, respectively. This exciting result opens the possibility to develop an economic catalyst with high efficiency from the abundant Indonesian mineral resource.

The one-pot four component synthesis of 3-(Imino)-2,3-dihydropyrrolo[2,1-a]isoquinoline-1,1(10bH)-dicarbonitrile derivatives via a catalyst-free reaction between aryl aldehydes, malononitrile, isoquinoline and isocyanides was successfully conducted in glycerol as a benign, nontoxic and biodegradable promoting reaction medium. The progress of the reaction with two different common purification methods were investigated. Moreover, synthesized products were examined as chemical sensors for the detection of a wide range of metal ions and it was successful for the detection of Co2+ ions.

Poly (phenylene-ether-ether) sulfone membrane was fabricated and characterized by efficient glycerol/biodiesel separation produced from waste cooking oils trans-esterification. The membrane preparation was processed by phase inversion technique. The morphology, Physico-chemical properties and separation behavior of membranes were studied at various PPEES concentration. A uniform surface was observed for the prepared membranes by scanning electron microscopy. AFM images exhibited that surface roughness was decreased from 9.24 to 7.26 nm by the increase of PPEES concentration from 12 to 15 %wt. Similar trend was found for the membrane Flux, water content, and porosity by the increase of PPEES content ratio up to 15 %wt. The efficiency of glycerol removal and mechanical strength was also improved by the increase of polymeric matrix concentration.

A new alkaline citrate bath has been formulated for electrodeposition of Ni-P alloy coatings through conventional Hull cell method, using glycerol as an additive. Electrodeposition following induced type of codeposition was carried out on mild steel (MS) substrate at different current densities (c.d.’s), using the basic bath. The influences of bath constituents and operating parameters on the appearance, hardness, thickness and composition of the deposits have been studied. Corrosion behavior of alloy coatings, having hard-adherent mirror bright appearance developed at different c.d.’s were studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods in 5 wt.% NaCl solution. Experimental results revealed that corrosion protection efficacy of NiP coatings increased with deposition c.d., in proportion of its P content up to an optimal limit, and then decreased. The coating developed at 4.0 A dm-2 was found to exhibit the least corrosion rate (14.2×10-2 mm y-1), compared to those at other c.d.’s. The process and products of electrodeposition have been studied using different methods, such as cyclic voltammetry (CV), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analyses. Experimental results were analyzed in the light of principles of induced codeposition and role of additives, and results are discussed.

In this work, the results concerning to the mean activity coefficient measurements for NaCl in the (glycerol water) system using the potentiometric method are reported. The potentiometric measurements were performed on the galvanic cells without liquid junction of the type: Ag|AgCl|NaCl (m), glycerol (wt%), H2O (1 - wt)%|Na-ISE, in various mixed solvent systems containing 0, 5, 10, 20 and 30 mass fraction percents of glycerol over ionic strength ranging from 0.0020-3 mol kg-1 at T = 298.2 K. The sodium ion selective electrode and Ag-AgCl electrode as self-made electrodes had a reasonably Nernst response. The modified zeolite was used to fabricate the sodium ion selective electrode as electrochemical sensor. The modeling of the investigated system was made based on an extended Debye-Hückel equation, the Pitzer and Pitzer-Simonson-Clegg models. The unknown parameters were determined for each model. The resulting values of the mean activity coefficients, osmotic coefficients and excess Gibbs energy are reported for the studied system.

The wheat straw as abundant lignocellulosic resource was successfully undergone in a benzylation reaction and plasticized with different contents (2.5, 3, 5 and 7 wt. %) of glycerol and stearic acid. The effect of type and concentration of plasticizers on the mechanical, thermomechanical, morphological and water absorption properties of Benzylated Wheat Straw (BWS) was investigated by tensile, Dynamic Mechanical Thermal Analysis (DMTA) measurements and Scanning Electron Microscopy (SEM), respectively. The experimental results show that addition of plasticizer may increase the elongation at break, and may decrease the tensile strength for the sheet plasticized with 5% or 7% stearic acid and 3% or 5% glycerol. The addition of 7% glycerol or 3% stearic acid make increase both tensile strength and elongation at break. These films are stronger but less tough compared to unplasticized BWS film. The porosity at the surfaces of samples from the SEM micrographs showed good correlation with the mechanical properties of the blends. On addition of plasticizer, it is observed that there is a decrease in the size of micro-pores and for higher concentration, it no longer exists. Compared with glycerol, the water absorption of the BWS films plasticized with stearic acid was significantly lower. Glycerol is soluble in water and removed from films after floating in water. The film plasticized with 2.5% both glycerol and stearic acid had better water resistance than others. As usual, glass transition temperatures of samples were decreased by addition of plasticizers according to DMTA results.

For the first time this study reported the success of using nanocrystalline hexagonal close-packed (hcp) nickel (Ni) modified composite graphite (CG) electrode (hcp-nano Ni/CG) for the electrocatalytic oxidation of glycerol in alkaline medium (0.1 M KOH). The hcp-nano Ni/CG electrode had an improve response and specificity on the electrocatalytic oxidation of glycerol over the bare CG. The electrocatalysis was the result of the formation of NiOOH during the oxidation process. The process was influenced by scan rate and concentration of glycerol. A linear relationship of concentration with current was obtained over concentration range of 0.5 – 12.0 mM glycerol with limit of detection (S/N = 3) at 0.033 mM glycerol. The hcp nano Ni modified CG electrode was applied for direct determination of free glycerol in biodiesel samples. As a glycerol sensor the hcp nano Ni modified CG is quite stable.