Ethanol Volume Fraction Research Articles

Comment for “Measurement and correlation of solubility of 2-chloro-3-(trifluoromethyl)pyridine in pure solvents and ethanol + n-propanol mixtures”

In a published paper of Journal of Molecular Liquids, a mistake was found. Wang and co-authors made a mistake about the calculation of Hildebrand solubility parameter of the mix solvent. ξ should be the volume fraction of ethanol in the mix solvent, not the mole fraction after consulting the related literatures and books. In order to avoid the similar mistake for other researchers, the comment for Wang's paper should be needed.

Precipitation study of CO2-loaded glycinate solution with the introduction of ethanol as an antisolvent

Focused beam reflectance measurement (FBRM) and 13C nuclear magnetic resonance (13C NMR) analysis were used to study the precipitation process of CO2-loaded potassium glycinate (KGLY) solutions at different CO2 loadings, during the addition of ethanol as an antisolvent at a rate of 10 mL·min−1. The volume ratio of ethanol added to the KGLY solution (3.0 mol·L−1, 340 mL) ranged from 0 to 3.0. Three solid-liquid-liquid phases were formed during the precipitation process. The FBRM results showed that the number of particles formed increased with CO2 loading and ethanol addition for CO2-unsaturated KGLY solutions, whilst for CO2-saturated KGLY solution it first increased then decreased to a stable value with ethanol addition. 13C NMR spectroscopic analysis showed that the crystals precipitated from the CO2-unsaturated KGLY solutions consisted of glycine only, and the quantity crystallised increased with CO2 loading and ethanol addition. However, a complex mixture containing glycine, carbamate and potassium bicarbonate was precipitated from CO2-saturated KGLY solution with the maximum precipitation percentages of 94.3%, 31.4% and 89.6%, respectively, at the ethanol volume fractions of 1.6, 2.5 and 2.3.

Optimization of ultrasound-assisted extraction of poly-phenols from Ajuga ciliata Bunge and evaluation of antioxidant activities in vitro

Effective extraction of natural antioxidants from cheap plant sources is still a problem. In this paper, an excellent method of ultrasound-assisted extraction of phenolic compounds from Ajuga ciliata Bunge was studied. The effects of four factors including ethanol volume fraction, ultrasonic time, ultrasonic temperature and material liquid ratio were discussed. After single factor experiments had been investigated, a 4-factor, 3-level Box-Behnken design experiment was used to obtain the model optimum conditions, which are shown as follows: ethanol volume fraction of 41%, liquid-solid ratio of 35:1 mL/g, ultrasonic temperature of 60 °C and ultrasonic time of 50 min. Under these conditions, the experimental productivity is 3.552 mg/g. The spectra of Fourier infrared and energy dispersive X-ray suggest that phenolic compounds exist in the extracts. Besides, free radical scavenging potentials of superoxide anion, hydroxyl and DPPH were measured to evaluate their antioxidant properties. This study proves that the ultrasonic-assisted extraction technique can extract phenolic compounds with antioxidant capacity from Ajuga ciliata Bunge.

Measurements of laminar flame speeds and flame instability analysis of E30-air premixed flames at elevated temperatures and pressures

Ethanol is regarded as one of the most promising alternative renewable fuels and as well as an oxygenate blending component in gasoline fuels, with widespread usage in many countries around the world. Laminar flame speeds can have strong influence on the stability and operability of Spark-Ignition combustion in certain operating regimes, and so the effects of different initial conditions on laminar combustion characteristics of E30 (gasoline blended with ethanol of 30% liquid volume) were analyzed in a constant-volume combustion vessel using the high-speed Schlieren method. This work presents results for equivalence ratios of 0.7–1.4, dilution ratios of 0%, 5%, 10%, and at different initial temperatures (408, 453 and 498 K) and initial pressures (1, 2 and 3 bar). It can be concluded that the laminar burning velocity has a positive correlation with initial temperature, but negative correlation with initial pressure and dilution ratio. The laminar burning velocity always reaches its maximum value at an equivalence ratio of 1.1 and does not change with varying initial conditions' the adiabatic flame temperature displays a similar variation with the initial conditions. The flame instability of E30-air mixture is enhanced as the initial pressure increases. Flame stability at lean and rich mixtures are exactly opposite at different initial temperature and dilution ratio. The laminar burning velocity was significantly promoted relative to gasoline and E10 by the addition of higher volume fractions of ethanol, highlighting one of the benefits of ethanol’s use as a blending component in gasoline fuels.

Physicochemical analyses, antioxidant, antibacterial, and toxicity of propolis particles produced by stingless bee Heterotrigona itama found in Brunei Darussalam

In this study, the physicochemical, antioxidant, antibacterial properties, and the toxicity of propolis particles produced by stingless bee Heterotrigona itama found in Brunei Darussalam were investigated. Propolis particles of different sizes were extracted from raw propolis using various volume fractions of ethanol in water. Spectroscopic analyses were utilized to characterize the chemical structures, functional groups, as well as absorbance and fluorescence properties. The total antioxidant capacity of propolis particles, which was assessed using DPPH (2,2-diphenyl-1-picrylhydrazyl) assay, was found to increase with volume fraction of ethanol. The maximum antioxidant capacity was as high as 317.65 mg ascorbic acid equivalent per gram of propolis particles. All of the propolis particles showed antibacterial activity against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). The diameters of the inhibition zone were either significantly higher or equivalent to those of two standard antibiotics (rifampicin and streptomycin), suggesting strong antibacterial activity. The toxicity studies of propolis particles against Caenorhabditis elegans revealed that they are non-toxic after 24 h exposure. Overall findings suggest that H. itama propolis particles are not only an important source of natural antioxidants that could be beneficial for human health, but they have potentials as antimicrobial against bacteria.

Heating and evaporation of ethanol/iso-octane droplets considering non-ideal mixtures and finite rate transfer

In this paper, the heating and evaporation process of ethanol/iso-octane droplets is deeply investigated through analytical solutions and considering thermodynamic models for non-ideal mixtures. The study is based on the Effective Thermal Conductivity Model (ECM) and Effective Diffusivity Model (EDM), which take into account the finite thermal/mass diffusivities inside the droplets and also consider the effect of droplet internal recirculation. Three sets of cases are considered: ideal liquid and gas phases, non-ideal liquid and gas phases and ideal gas phase together with the non-consideration of the Poynting factor for the liquid phase. The activity coefficients for the non-ideal liquid phase are calculated through the UNIFAC model and the fugacity coefficients for the non-ideal gas phase are calculated from the Virial equation of state. A parametric study is performed with focus on relevant conditions to direct injection internal combustion engines, within an ambient pressure range from 1 to 20 bar, initial ambient gas temperature range from 453 K to 673 K and initial ethanol volume fraction inside the droplet varying from 0 to 1. The thermodynamic analysis of the mixture, the time evolution of the droplet surface temperature and mass fraction together with the droplet lifetimes are presented for several different conditions. The obtained results show that the effect of the non-ideality of both phases has a significant impact on the results when analyzing ethanol/iso-octane mixtures. From cases analyzed considering both phases as ideal mixtures the deviation of the droplet lifetime reached maximum values (in absolute value) of 15.6% at 1 bar, 10.5% at 10 bar and 14.9% at 20 bar and for the ideal gas approach (non-ideal liquid) the deviation reached maximum values (in absolute value) of 3.9% at 10 bar and 9.4% at 20 bar, when compared to the non-ideal approach. These deviations certainly can lead to significant deviations in the prediction of the mixture formation in direct injection engines.

Experimental study on effects of ethanol-diesel fuel blended on spray characteristics under ultra-high injection pressure up to 350 MPa

In the present study, the atomization characteristics of ethanol-diesel blends fuel spray and shock waves were investigated by using experimental methods under ultra-high injection pressure in the range 200Mpa–350 MPa. A high-speed camera and Schlieren technology were used to visualize the fuel spray morphology and shock waves. The spray tip penetration, velocity and shock wave angle were determined via experimental approaches. Furthermore, the special spray shape under ultra-high injection pressure, such as liquid tail, expanded body and bifurcated structures, was analyzed. To validate the classical spray empirical models, predicted spray penetration results based on two typical models (Dent's and Hiroyasu's model) were compared with experimental data. The results indicated that fuel injection pressure and ethanol volume fraction presented significant effects on the spray evolution. With increasing injection pressure, the spray tip penetration became faster and the induced attached shock waves reveal clearer. The fuel spray jets achieved the larger penetration velocity and more induced shock waves under higher injection pressure or lower ethanol volume fraction.

Efficient Homogenization-Ultrasound-Assisted Extraction of Anthocyanins and Flavonols from Bog Bilberry (Vaccinium uliginosum L.) Marc with Carnosic Acid as an Antioxidant Additive.

To explore the optimum conditions for the extraction of anthocyanins and flavonols from bog bilberry (Vaccinium uliginosum L.) marc on a single-factor experimental basis, a response surface methodology was adopted for this intensive study. The extraction procedure was carried out in a Waring blender and followed an ultrasonic bath, and the natural antioxidant carnosic acid was added to inhibit oxidation. The optimum extraction conditions were as follows: a volume fraction of ethanol of 70%, an antioxidant content of 0.02% (the mass of sample) carnosic acid, a liquid–solid ratio of 16 mL/g, a homogenization time of 3 min, a reaction temperature of 55 °C, an ultrasound irradiation frequency of 80 kHz, an ultrasound irradiation power of 200 W, and an ultrasound irradiation time of 40 min. Satisfactory yields of anthocyanins (13.95 ± 0.37 mg/g) and flavonols (3.51 ± 0.16 mg/g) were obtained. The experimental results showed that the carnosic acid played an effective antioxidant role in the extraction process of anthocyanins and flavonols with a green and safety guarantee.

Effect of air turbulence and fuel composition on bi-component droplet evaporation

Understanding the influence of fuel composition and air turbulence on evaporation of bi-component fuel droplet is the aim of the current investigation. Experiments were carried out with a single fuel droplet (a mixture of n-heptane and ethanol) suspended using the cross-wire technique within a box of turbulence facility that is capable of generating near zero-mean homogeneous and isotropic turbulence at its center. The fuel composition (i.e. the volume fraction of ethanol) as well as turbulent intensity within the chamber were varied over a wide range. The images of the evaporating droplet were recorded using back-light illumination. The initial droplet size was about 30–40 times smaller than the integral length scale of air turbulence, while it was about 10 times larger than the Kolmogorov length scale. For each fuel composition, five different turbulent conditions were considered. While the effect of turbulence was found to enhance droplet evaporation rate for all cases, the extent of its influence depends on fuel vapor mass diffusivity in air, and, in addition, on the initial fuel composition of the binary mixtures. The evaporation constant for the first stage of evaporation is sensitive to both air turbulence level and composition, while that for the second stage of evaporation shows a specific trend with fuel composition for all cases of turbulent intensity. Finally, an experimental correlation for normalized evaporation constant is presented.

Natural antioxidant of rosemary extract used as an additive in the ultrasound-assisted extraction of anthocyanins from lingonberry (Vaccinium vitis-idaea L.) pomace

The effects of natural antioxidant rosemary extracts with different carnosic acid concentrations (30%, 60%, and 90%) and of three synthetic antioxidants in the extraction of anthocyanins from lingonberry (Vaccinium vitis-idaea L.) pomace under ultrasound irradiation conditions were compared. The optimum extraction conditions were selected: antioxidant rosemary extract with carnosic acid of 30% (purity), 0.02% (carnosic acid to lingonberry pomace sample mass ratio); ethanol volume fraction, 40%; pH 1.5; liquid–solid ratio, 20 mL/g; ultrasound frequency, 80 kHz; ultrasound irradiation power, 170 W; reaction temperature, 55 °C; and ultrasound irradiation time, 35 min. Compared with traditional extraction techniques (no addition of rosemary extract), we obtained satisfactory yields of anthocyanins of 4.12 ± 0.18 mg/g (cyanidin-3-galactoside yield of 3.36 ± 0.14 mg/g, cyanidin-3-glucoside yield of 0.15 ± 0.01 mg/g and cyanidin-3-arabinoside yield of 0.61 ± 0.03 mg/g). The supplement of natural antioxidant rosemary extract was first added to inhibit the oxidation of anthocyanins, and the proposed natural antioxidant rosemary extract exhibited potential to replace synthetic antioxidants with greater security.

Green, infrared‐assisted extraction based on statistical modeling for ultra‐high performance liquid chromatography determination of bioactive isoflavones from Puerariae Lobatae

AbstractWe developed a green infrared‐assisted extraction method for the determination of 3′‐hydroxy puerarin, puerarin, daidzin, genistin, and daidzein in Pueraria lobata. After a simultaneous optimization of Box–Behnken design and desirability function, the developed method provided better isoflavone extraction efficiencies with a lower solvent consumption and shorter extraction time than other methods. The optimized extraction used an extraction time of 8 min, solid–liquid ratio of 1:100, and ethanol volume fraction of 60%. Additionally, ultra‐high performance liquid chromatography was used for identification and quantification of the five isoflavones. Our method showed good linearity (r >0.999) over wide concentration ranges. The ranges for the limits of detection and quantitation were 0.03–0.09 μg/mL and 0.14–0.44 μg/mL, respectively, the recovery range was 98.38–103.37%, and the run time was 5.5 min. This approach is efficient, economical, and eco‐friendly, and shows promise for rapid extraction and quantitative analysis of bioactive isoflavones from Pueraria lobata.

Extraction optimization, antioxidant activity, and tyrosinase inhibitory capacity of polyphenols from Lonicera japonica.

The objective of this research was twofold: first, to optimize the extraction process of Lonicera japonica polyphenols using a response surface methodology, and second, to study the antioxidant activity and tyrosinase inhibitory capacity of the polyphenols of different purities. High‐speed shearing homogenization extraction was used to extract the polyphenols from L. japonica. The antioxidant activity and the effect of polyphenols on tyrosinase activity were studied using free radical scavenging assay and the tyrosinase method, respectively. The optimal extraction conditions with an extraction yield of 6.96% for polyphenols were determined as follows: ethanol volume fraction 57%, shearing time 3.30 min, and solid–liquid ratio 1:58. Lonicera japonica polyphenols exhibited potent scavenging activity on 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and 2, 2'‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS), and inhibitory capacity on tyrosinase. The results suggested that L. japonica polyphenols could be explored as a natural antioxidant and tyrosinase inhibitor.

Thermodynamics of complex formation between hydroxypropyl-β-cyclodextrin and quercetin in water–ethanol solvents at T = 298.15 K

Quercetin (QCT) is a flavonoid possessing many activities, such as neuro-/cardioprotective, anti-inflammatory and anticancer, but its pharmacological application is severely curtailed by its low water solubility and in vivo bioavailability. The formation of a QCT–hydroxypropyl-β-cyclodextrin (HPβCD) host–guest complex is promising to improve QCT therapeutic potential. Therefore, here the heat effects of HPβCD solutions with QCT solutions in water–ethanol solvents at different concentrations were studied by calorimetric titration, and the stability of molecular complexes was assessed by UV–Vis spectrophotometry. Calorimetric titrations revealed the formation of a QCT/HPβCD host–guest complex with a stoichiometric ratio of 1:1 in X(EtOH) = 0.00, 0.05 and 0.10 molar fractions of solvents at pH = 7.0 and pH = 8.1. Thermodynamic parameters of the complex formation reaction (lgK; ΔrH; TΔrS) were obtained in these experimental conditions. Differently, no complex formation was noticed in water–ethanol mixed solvent when ethanol volume fraction exceeded 0.2 at neutral and alkaline pH, as well as a volume fraction higher than 0.1 at acidic pH. Furthermore, the results of differential scanning calorimetry tests run on dried HPβCD after dissolution in hydroalcoholic solutions indicated that ethanol and water compete for the complexation within the hydrophobic cavity of HPβCD. This explains the decreased QCT complexation efficacy in the presence of ethanol beyond 0.1 or 0.2 volume fraction.

Optimization, evaluation and identification of flavonoids in Cirsium setosum (Willd.) MB by using response surface methodology

Medicinal and edible homologous plant is receiving widespread attention due to its particularity. As an edible wild vegetable, Cirsium setosum (Willd.) MB is used to treat various bleeding diseases. This work aims to investigate the technological conditions for ultrasound assisted extraction of flavonoids in C. setosum (Willd.) MB. Using a Box–Behnken design as an experimental model, the optimum extraction process of flavonoids was studied by response surface methodology. The conditions for optimal parameters were: the ratio of liquid–solid 39.21 mL/g, the volume fraction of ethanol 71.55%, the ultrasonic time 37.76 min and the temperature 65.28 °C. This study demonstrated that flavonoids yield was greatly affected by the solid/liquid ratio as well as ultrasonic temperature, while, ethanol volume fraction and ultrasonic time had less influence during extraction. In contrast to Vc and BHT, the C. setosum (Willd.) MB flavonoids extract had a more potent scavenging ability towards DPPH radicals, hydroxyl radicals and superoxide anions. Furthermore, the reduction activity was much stronger than BHT but slightly weaker than Vc. Four flavonoids, the main contributors to the antioxidant activity of C. setosum (Willd.) MB including rutin, nicotiflorin, diosmin and linarin were identified through UPLC–MS.

Laminar burning velocities of iso-octane, toluene, 1-hexene, ethanol and their quaternary blends at elevated temperatures and pressures

Increasing environmental concerns caused interest in alternative fuels among which ethanol is regarded as possibly the best candidate to augment fossil fuels. Ethanol can easily be blended with hydrocarbons. Laminar burning velocity is a fundamental property of fuel for spark ignition engines. Adiabatic laminar burning velocities have been measured using the constant volume method along with the Schilieren optical system, for iso-octane, toluene, 1-hexene, ethanol and the quaternary blends with ethanol volume fractions of 0%, 20%, 50%, and 85% and equal fraction of other three components. Measurements were conducted for equivalence ratios from 0.7 to 1.4, temperatures of 298 K, 380 K and 450 K, and pressures of 1 bar, 2 bar and 4 bar. Close agreements were found between the present results and literature data for pure components. Adding 20% ethanol doesn’t increase the burning velocity of the blend by much, particularly for lean mixture. Higher volume fraction of ethanol (over 20%) leads to a higher laminar burning velocity of the blend and the burning velocity peaks at richer mixture. High temperature and high volume fraction of ethanol lead to earlier cellular flame of the quaternary blends.

Enrichment and Purification of Aucubin from Eucommia ulmoides Ionic Liquid Extract Using Macroporous Resins.

Aiming to address the shortcomings of high-concentration ethanol or methanol extraction solutions that need to be diluted and concentrated prior to use in conventional macroporous resin adsorption approaches, an efficient approach for enrichment and purification of aucubin from the ionic liquid extraction solution of samaras of Eucommia ulmoides was proposed. Among the nine kinds of macroporous resins investigated, the HPD850 resin was found to be the most suitable. Equilibrium adsorption tests were investigated and found to be better fitted by the Langmuir isotherm model. After the dynamic tests on a column packed with HPD850, the optimum operational conditions were as follows: for the absorption process, an initial aucubin concentration of 9.87 mg/L, a sample volume of 13 bed volumes (BV), and a flow rate of 2 BV/h; for the water washing process, 5 BV of deionized water and a flow rate of 3 BV/h; for the ethanol desorption process, a 10–80% ethanol volume fraction as the eluent, 2 BV for each ethanol volume fraction, and a flow rate of 3 BV/h. The 40–80% ethanol volume fraction eluent was collected and concentrated to produce the final products, resulting in an aucubin purity and recovery of 79.41% and 72.92%, respectively.

Optimization of Vacuum Microwave-Mediated Extraction of Syringoside and Oleuropein from Twigs of Syringa oblata.

A vacuum microwave-mediated method was used to extract syringoside and oleuropein from Syringa oblata twigs. The optimal extraction conditions were an ethanol volume fraction of 40%, a liquid-solid ratio of 17 mL/g, 1 h of soaking time, −0.08 MPa of vacuum, a microwave irradiation power of 524 W, and a microwave irradiation time of 8 min. Under optimal parameters, the maximum yields of syringoside (5.92 ± 0.24 mg/g) and oleuropein (4.02 ± 0.18 mg/g) were obtained. The proposed method is more efficient than conventional methods for extracting syringoside and oleuropein from Syringa oblata. Moreover, less energy and time were required. The results implied that vacuum microwave-mediated extraction is a suitable method for the extraction of thermosensitive glycosides such as syringoside and oleuropein.

Ultrasonic Analyzers of Ethanol in Automotive Gasoline

Ultrasonic analyzers of ethanol in automotive gasoline are reviewed. These devices allow determination of the volume fraction of ethanol in ethanol-gasoline mixtures in the range from 0 to 100 %. The relative error of measurement of 5 % volume fraction of ethanol is 0.107–0.427 %, and the relative error of measurement of 100 % volume fraction of ethanol is 0.005–0.021 %. Analysis time is several milliseconds.

Synthesis of poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate) with low polydispersity using ultrasonic irradiation

Poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate) having low polydispersity was synthesized in mixed solvent of ethanol and water using ultrasonic irradiation without any chemical polymerization initiator. The effects of the volume fraction of ethanol in the solvent, the molar ratio of two monomers, the monomer concentration and the ultrasonic power intensity on the time courses of the conversion to the polymer, the number average molecular weight, and the polydispersity of synthesized polymer were investigated in order to determine the optimal conditions to synthesize the copolymers with a narrow molecular weight distribution (i.e. low polydispersity). The optimum volume fraction of ethanol in the solvent was 60 vol% to synthesize the copolymers with a low polydispersity. A higher ultrasonic power intensity resulted in a faster polymerization rate and a lower number average molecular weight. The polydispersity was less than 1.5 for all ultrasonic power intensities up to 450 W/dm3 applied in this work. A higher monomer concentration gave a faster polymerization rate and a higher number average molecular weight. The polydispersity was less than 1.5 when the monomer concentration was lower than 0.4 mol/dm3. A higher molar ratio of N-isopropylacrylamide resulted in a higher polymerization rate and a lower number average molecular weight. The copolymers with polydispersity less than 1.5 can be obtained regardless of the molar ratio of N-isopropylacrylamide. The copolymers synthesized by the ultrasonic polymerization method had a high temperature responsibility.

Experimental investigation on heat transfer of spray cooling with the mixture of ethanol and water

Experiments were conducted to investigate the performance of the spray cooling heat transfer. Pure water and the mixture of water and ethanol (the volume fraction of ethanol ranges from 0.05% to 10%) were used as working fluids. The performance of pure water and the mixture were compared using the identical heater and solid-cone spray nozzle. The maximum heat flux in the experiment was up to 170 W/cm2. The experimental results indicated that adding ethanol to water is one of the most effective methods to enhance the heat dissipation and to control the device temperature simultaneously. The volume fraction of ethanol in water is the main factor affecting the spray cooling performance. The optimal volume fraction of ethanol for the improvement of the heat transfer performance is 4%.