Water Content In Ethanol Research Articles

A Simple and Fast Procedure forin situDetermination of Water in Ethanol Fuel

A simple and inexpensive procedure, based on the high difference in solubility of sodium chloride in ethanol and water, is proposed to estimate the water content in ethanol fuel. The ionic concentration of solutions saturated with the salt is monitored by conductometric measurements with a linear response up to 16% water in an alcoholic medium and a limit of detection of 0.05% (v/v). The procedure is precise (coefficient of variation of 0.6%, n = 10) and accurate (results in agreement with those obtained by Karl Fischer amperometric titration at the 95% confidence level). An indicating electronic device exploiting the same principle was proposed for in situ monitoring of ethanol fuel samples aiming at the fast detection of unconformities. The device can be operated by nonexperts, generating a binary response indicated by coloured LEDs, and it successfully classified commercial samples spiked with different amounts of water.

Partition of Free Fatty Acids in Deacidification of Macaúba Pulp Oil by Liquid-Liquid Extraction Using Ethanol/Water as Solvent

Free fatty acids (FFA) is one of the most frequently determined quality indices in fats and oils industry because it has the economic impacts on production [1]. The FFA in macaúba pulp oil is usually very high (10 to 40%) due to enzymatic activity in the raw material [2]. In this case, alkali neutralization is not economically recommended due to neutral oil loss by occlusion in soapstock. The differential solubility of fatty acids and triacylglycerides (TAG) in various organic solvents has formed the basis of several processes for deacidification of crude oils by liquid–liquid extraction [3]. The aim of the present work was to evaluate the influence of raw oil acidity, ethanol/water ratio, water content in ethanol and temperature extraction on partition coefficients of FFA during macaúba oil deacidification. The macaúba crude oil presented high acid index, about 86  1.2 mg KOH/g. The extraction data for the system macaúba oil + free fatty acids + ethanol + water was determined for oil:solvent mass ratios 1:1. Alcoholic solutions containing 2 to 10 % (w/w) of water were used to FFA extraction and the partition coefficients were determined after 24 hours at room temperature (293 K). The phase’s separation was observed for water content in the mixture above 4%. After solvent evaporation, the FFA in oil phase was evaluated by AOCS standard method. Regarding the high acid oil, the single stage liquid-liquid extraction reduced the FFA in macaúba pulp oil in about 23 % while the three batch stages reduced up to 60%. At the selected parameters (ethanol 94oGL, solvent/substrate ratio = 2), the partition coefficients in the firs stage to FFA (KFFA) were 30.45, 12.00 and 1.95, respectively to high acid, acid and low acid macaúba oils and the partition coefficients to TAG (KTAG) were 7.07, 0.04 and 0.02, respectively to high acid, acid and low acid macaúba oils. These results show the potential of ethanol to vegetable oil deacidification. Besides reduced generation of environmental pollutants, this new approach could also lead to reduction in oil losses, especially for low acid oil.

Surface plasmon resonance based fiber optic sensor for the detection of low water content in ethanol

A fiber optic sensor utilizing surface plasmon resonance (SPR) has been fabricated for the detection of low content of water in ethanol. The sensor utilizes spectral interrogation technique for operation. The resonance wavelength has been found to vary linearly with water content in the range 0–10% with sensitivity of 1.149 nm per percentage of water. The results are in agreement with the refractive index variation of ethanol–water mixture. The sensor has a water resolution of 0.145% which is better than the evanescent wave absorption sensor reported for the similar study. The sensor will find application in determining the low water content in ethanol which is used as a bio-fuel and in the field of medicine and organic chemistry.

Supercritical fluid extraction of flavonoids from Maydis stigma and its nitrite-scavenging ability

Supercritical fluid carbon dioxide (SF-CO 2) extraction (SFE) of flavonoids from Maydis stigma and its nitrite-scavenging ability were investigated. The effects of extraction time, particle size and co-solvent composition in terms of water content in ethanol were first optimized. Then, a Box–Behnken design combined with response surface methodology (RSM) was employed to study the effects of three independent variables (temperature, pressure and co-solvent amount) on the extraction yield of flavonoids. A maximal extraction yield of flavonoids of approximately 4.24 mg/g of M. stigma by SFE was obtained under optimal conditions (a temperature of 50.88 °C, a pressure of 41.80 MPa, a co-solvent amount of 2.488 mL/g and an extraction time of 120 min with 0.4-mm particle sizes and 20% aqueous ethanol as the co-solvent). Furthermore, the nitrite-scavenging ability of the flavonoid-enriched SFE extracts was assessed using the Griess reagent. The flavonoid-enriched SFE extracts exhibited the highest scavenging ability on nitrite (88.1 ± 3.04%) at the concentration of 500 μg/mL and at pH 3.0. The nitrite-scavenging ability of the extracts appeared to be concentration dependent but negatively correlated with the pH.

Adsorption Isotherms for Removal of Linoleic Acid from Ethanolic Solutions Using the Strong Anion Exchange Resin Amberlyst A26 OH

Adsorption isotherms for the removal of linoleic acid from aqueous ethanol were measured using a strong anion exchange resin (Amberlyst A26 OH). The data for linoleic acid were compared with previously published results for oleic acid. The equilibrium data were correlated using the Langmuir and Freundlich isotherms. Lower average deviations between experimental and calculated results were obtained with the Langmuir model. The capacity of the resin for adsorbing linoleic acid was evaluated at different water contents in ethanol, 100 w = 0.50 to 15.27, and at 298.15 K. The water content in ethanol does not influence significantly the equilibrium behavior, and the strong anion exchange resin has a good performance in the removal of linoleic acid from the liquid phase.

Vanadium oxide-porphyrin nanocomposites as gas sensor interfaces for probing low water content in ethanol

Vanadium pentoxide xerogels (VXG) incorporating meso(3- and 4-pyridyl)porphyrin cobalt(III) species coordinated to four [Ru(bipy) 2Cl] + complexes were employed as gas sensing materials capable of detecting small amounts of water in commercial ethanol and fuel supplies. According to their X-ray diffraction data, the original VXG lamellar framework was maintained in the nanocomposite material, but the interlamellar distance increased from 11.7 to 15.2 Å, reflecting the intercalation of the porphyrin species into the vanadium pentoxide matrix. The films generated by direct deposition of the nanocomposite aqueous suspensions exhibited good electrical and electrochemical performance for application in resistive sensors. The analysis of water in ethanol and fuels was carried out successfully using an especially designed electric setup incorporating a laminar gas flow chamber and interdigitated gold electrodes coated with the nanocomposites.

Determination of low-level water content in ethanol by fiber-optic evanescent absorption sensor

Evanescent field absorption spectroscopy in the infrared range of coiled fiber-optic sensor has been applied to determine the low-level water content in ethanol. Principal component regression and classical least square models have been utilized to build the calibration model and predict the water concentrations. The standard errors of predictions of water concentrations in ethanol were 3.16% and 0.42% respectively. Some methods to improve the accuracy of predicted water concentration in ethanol were suggested. The predicted concentration of water is acceptably accurate and cost-effective. The study demonstrates that the coiled fiber-optic sensor based on evanescent absorption spectroscopy is a feasible technology for prediction of the low-level water content in bio-ethanol and other industries in both on-line and remote situation.

Extraction of nobiletin and tangeretin from Citrus depressa Hayata by supercritical carbon dioxide with ethanol as modifier

An optimal condition of supercritical fluid extraction for two polymethoxyflavones (PMFs), nobiletin and tangeretin, from Citrus depressa Hayata was developed. The effect of modifier type, modifier composition in terms of water content in ethanol, modifier percentage, extraction condition (temperature, pressure and CO 2 flow rate), and particle size on the yield of nobiletin and tangeretin were investigated. The contents of nobiletin and tangeretin were determined by HPLC. Results showed that the yield of nobiletin and tangeretin increased significantly with increased percentage of aqueous ethanol (85%) as a modifier in supercritical carbon dioxide up to 9.1%. The optimal temperature and pressure for selective supercritical fluid extraction (SFE) of nobiletin and tangeretin were 80 °C and 30 MPa, respectively. The extraction rate was increased by increasing CO 2 flow rate. The optimal particle size of sample was found to be 0.375 mm. Overall, the nobiletin and tangeretin yield of SFE was 107% compared to conventional solvent extraction method (100%). Therefore, application of SFE for extraction of nobiletin and tangeretin from C. depressa Hayata peel was preferable.

Hydrous ethanol vs. gasoline-ethanol blend: Engine performance and emissions

This work compares the performance and emissions from a production 1.0-l, eight-valve, and four-stroke engine fuelled by hydrous ethanol (6.8% water content in ethanol) or 78% gasoline-22% ethanol blend. The engine was tested in a dynamometer bench in compliance with NBR/ISO 1585 standard. The performance parameters investigated were torque, brake mean effective pressure (BMEP), brake power, specific fuel consumption (SFC), and thermal efficiency. Carbon monoxide (CO), carbon dioxide (CO 2), hydrocarbons (HC) and oxides of nitrogen (NO X ) exhaust emissions levels are also presented. The results showed that torque and BMEP were higher when the gasoline-ethanol blend was used as fuel on low engine speeds. On the other hand, for high engine speeds, higher torque and BMEP were achieved when hydrous ethanol fuel was used. The use of hydrous ethanol caused higher power at high engine speeds, whereas, for low engine speeds, both fuels produced about the same power. Hydrous ethanol produced higher thermal efficiency and higher SFC than the gasoline-ethanol blend throughout all the engine speed range studied. With regard to exhaust emissions hydrous ethanol reduced CO and HC, but increased CO 2 and NO X levels.

WITHDRAWN: Determination of low-level water content in ethanol by fiber-optic evanescent absorption sensor

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Effect of water blending on bioethanol HCCI combustion with forced induction and residual gas trapping

Abstract There is increased interest worldwide in renewable engine fuels as well as in new combustion technologies. Bioethanol is one of the alternative fuels that have been used successfully in spark ignition engines. A combustion technology that currently attracts a lot of interest is the homogeneous charge compression ignition (HCCI) combustion, which has shown potential for low nitrogen oxides emissions with no particulate matter formation. The authors have shown previously that applying forced induction to bioethanol HCCI with residual gas trapping results in an extended load range compared to naturally aspirated operation. However, at high boost pressures, high cylinder pressure rise rates develop. Work by other researchers has shown that direct injection of water can be used as a combustion control method. The present work explores water blending as a way that might have an effect on combustion in order to lower the maximum pressure rise rates and further improve emissions. The obtained experimental results show that in contrast to variable rate direct injection of water, fixed rate water–ethanol blending is counterproductive for the reduction of pressure rise rates at higher loads. In addition, increasing the water content in ethanol results in reduction of the effective load range and increased emissions.

Effect of inlet valve timing and water blending on bioethanol HCCI combustion using forced induction and residual gas trapping

It has been shown previously that applying forced induction to homogeneous charge compression ignition (HCCI) combustion of bioethanol with residual gas trapping, results in a greatly extended engine load range compared to normal aspiration operation. However, at very high boost pressures, very high cylinder pressure rise rates develop. The approach documented here explores two ways that might have an effect on combustion in order to lower the maximum pressure rise rates and further improve the emissions of oxides of nitrogen (NO x ); inlet valve timing and water blending. It was found that there is an optimal inlet valve timing. When the timing was significantly advanced or retarded away from the optimal, the combustion phasing could be retarded for a given lambda (excess air ratio). However, this would result in higher loads and lower lambdas for a given boost pressure, with possibly higher NO x emissions. Increasing the water content in ethanol gave similar results as the non-optimal inlet valve timing.

Spectrophotometric Determination of Water Content in Alcohol Organic Solvents

AbstractIn this work, the absorption spectral characteristics and color‐change reaction mechanism of cobalt(II) chloride(CoCl2) in alcohol organic solvents has been investigated in the presence of water, and then the optimum conditions for determining the water content in the solvents were selected. Results indicated that the absorption spectra of CoCl2 in alcohols decreased with the increment of water content. At the maximum absorption wavelength of 656 nm, there were good linear relationships between the logarithm of the absorbance and the water content in organic solvents such as ethanol, n‐propanol, iso‐propanol and n‐butanol with related coefficients in the range of 0.9996˜0.9998. For determining water content in organic solvents, this method is simple, rapid, sensitive, reproducible and environmentally friendly. Furthermore, the linear range cannot restrict determination of the water content in organic solvents. This method had been applied to determine the water content in ethanol and n‐butanol with satisfactory recovery of water in n‐butanol between 98.41%˜101.29%.

Influences of experimental parameters on the stability of a benzoporphyrin drug in water/ethanol mixtures: a statistical approach investigation

The benzoporphyrin derivative, named B3B, is a promising new drug for application in photodynamic therapy. In aqueous organic solvent mixtures, B3B, can be used in topical application for superficial diseases, like for skin cancer. In this paper, the self-aggregation phenomena of porphyrin molecules in aqueous media was investigated using a chemometric tool to evaluate the effects of experimental variables on the stability of the B3B monomer in water/ethanol mixtures. A 23factorial design was employed which permitted determination of the magnitude of experimental parameters which influence aggregation of the drug at different pHs using the minimum number of experiments. At first, the pKavalues of the B3B in water/ethanol mixtures were determined by spectrophotometric measurements, resulting in pKa1= 3.3 and pKa2= 5.7, corresponding to the imino nitrogens and carboxylic groups, respectively. The experimental variables (B3B concentration, time and water/ethanol composition) were evaluated in three protonation states of the drug, at pH 7.0, 4.1 and 2.6. The two levels (low and high) were set up at: time 5 (-) and 360 minutes (+); [B3B] 4.4 × 10-6(-) and 26.5 × 10-6M (+); and water content in ethanol 40 (-) and 60% (+). The main parameter that determines the magnitude of the effects seems to be the charge component of B3B, which can be modulated by the pH. The results from the 23fractional design indicated that the main variable inducing B3B aggregation is the water percentage in ethanol at each pH selected. The magnitude of this effect was pronounced at pH 4.1 where the carboxylic and nitrogen free base forms of B3B are maintained. The factors of time and [B3B], despite being small, are not insignificant. Finally, the effect of water content was investigated in a wide range of water percentage in these three pHs.

Adsorption Isotherms for Oleic Acid Removal from Ethanol + Water Solutions Using the Strong Anion-Exchange Resin Amberlyst A26 OH

Adsorption isotherms for the removal of oleic acid from ethanol + water solutions using a strong anion-exchange resin (Amberlyst A26 OH) were experimentally determined. The equilibrium data were correlated using the Langmuir model by adjusting the parameters qm/(g of acid·g of dry resin-1), maximum content that can be adsorbed on solid phase, and Kd/(g of acid·g of solvent-1), the equilibrium constant. The Freundlich and Redlich−Petersen models were also used, but the Langmuir model shows the lower average deviations between experimental and calculated results. The behavior and the capacity of the resin to remove the fatty acid from the liquid phase were evaluated at different experimental conditions: the water content in ethanol was varied within the range (0 to 15) mass %, and two equilibrium temperatures were investigated: (298.15 and 313.15) K. It was observed that both variables, water content in ethanol and equilibrium temperature, do not significantly influence the equilibrium behavior. It was also observed that the strong anion-exchange resin (Amberlyst A26 OH) has a good performance in the removal of the fatty acid from the liquid phase. To determine exactly the mechanism for the uptake of oleic acid by the resin, equilibrium experiments were done with different oleic acid concentrations (7, 9, and 11) mass % in solution with water content in ethanol (0.57 ± 0.01) mass % at 298.15 K. In this way the concentration of oleic acid in resin phase was determined, and it was observed than the most important mechanism of uptake is the ion exchange.

Determination of Water Content in Ethanol by Miniaturized Near-Infrared (NIR) System

The miniaturized NIR (Near-infrared) spectrometer has been utilized for the determination of water content (1-19% range) in ethanol that is the most popular organic solvent in pharmaceutical industries. It has many potential capabilities that can replace the conventional analyzers especially for the on-line measurement since it is compact, versatile and cost-effective. By using two dimensional (2D) correlation spectroscopy, it was preliminarily investigated to find any unforeseen spectral distortion among the spectra collected from the miniaturized spectrometer. The 2D study revealed that the spectral variation clearly followed the variation of water concentration without any spectral distortion or abnormality. PLS (Partial Least Squares) was employed to build the calibration model and the resulting prediction performance was acceptable and stable over several days. Even though the miniaturized NIR system was evaluated to fairly simple chemical matrix, the overall study demonstrates the sufficient feasibility for diverse practical and industrial applications.

FA monoalkylesters from rice bran oil by in situ esterification

AbstractExtraction and in situ esterification of rice bran oil with ethanol were investigated by studying the effects of rice bran oil FFA content and water content of ethanol. Ethyl ester formation in the ethanol phase increased as FFA content increased. Neutral oil solubility in this phase fell considerably, resulting in a high ethyl ester content. The decrease of the water content in ethanol led to an increase in neutral oil solubility in ethanol and promoted the equilibrium of reaction to ethyl‐ester formation, resulting in lower FFA content of the product. The main factor that affected yield and monoester content when using high‐acidity bran and various monohydroxy alcohols was the solubility of neutral oil in alcohol. The highest monoester content was obtained with methanol.

The anodic behaviour of iron in ethanol—water solutions in the presence and absence of NaClO 4 as the supporting electrolyte

The anodic behaviour of iron in ethanol—water solutions and the effect of NaClO 4 have been investigated on the basis of potentiostatic polarization curves and electrochemical impedance plots. The influence of the water content in ethanol (6–80 vol.%) on the anodic polarization curves without a supporting electrolyte is to increase the anodic current density monotonically with potential. Furthermore, for a given potential, the current density is higher when the water content is increased. In the presence of NaClO 4 the polarization curves shift towards more high current in the low anodic potential range. Thus, addition of NaClO 4 not only increases the conductivity of ethanol solutions in its role as a supporting electrolyte, but it also modifies the electrochemical process significantly.