Water Content In Ethanol Research Articles

Walnut oil deacidification by liquid–liquid extraction with ethanol in a single- and multistage crossflow process

Liquid–liquid extraction of vegetable oil with ethanol predominantly removes the components having the greatest affinity for ethanol, such as free fatty acids responsible for the acidity of oil, but also some contaminants such as phthalates. The aim of this work is to study the effect of several operating parameters on the deacidification process: the initial free fatty acid content in oil (3.1, 5.8, 7.6 and 11.7% OA eq.), the ethanol-water content in solvent (70.0/30.0, 80.0/20.0, 87.8/12.2 and 95.6/4.4 g/g), and the oil/solvent ratio (0.50, 0.75 and 1.00 g/g). The economic assessment of the deacidification based on the costs of distilling solvent and neutral oil loss showed that the use of solvents containing 82 to 90 wt.% of ethanol enables to achieve a trade-off between efficiency of the extraction of free fatty acid and the neutral oil losses. A three-stage crosscurrent extraction using a solvent at 88.6 wt.% of ethanol (global solvent/oil ratio: 8.0 g/g) reduced the free fatty acid content from 5.8% OA eq. (in crude walnut oil) to 0.3–0.4% OA eq. with a loss of 4.0% of neutral oil mass. Regarding the extraction of phthalates, our results showed that the lower the water content in the hydroethanolic solvent, the more efficient the extraction of butyl benzyl phthalate (BBP). Moreover, extraction with ethanol has successfully reduced the BBP content below the current regulatory limit.

A portable smartphone-based colorimetric sensor for rapid determination of water content in ethanol

Herein, a simple, low cost and portable smartphone-based colorimetric sensor was introduced for rapid determining water content in ethanol. The method was based on the color-changing of cobalt(II) chloride in ethanolic solution followed by sensing and data processing using a colorimetric sensor. The sensor consisted of a smartphone as a detector, illumination source and data processor, and a lab-made box to hold the smartphone and sample cell. The effect of key experimental factors on the response was investigated. A linear response in the range of 0.05–2.00% v/v was observed with the detection and quantification limits of 0.02 and 0.05% v/v, respectively. The sensor was successfully applied for the determination of water content in several ethanolic solutions with recoveries higher than 88%. The method was an environmentally and economic friendly technique since it consumed only 78 mg of CoCl2 per 100 tests and required about 30 s for each assay.

Ethanol conversion into 1,3-butadiene over a mixed Hf-Zn catalyst: Effect of reaction conditions and water content in ethanol

Assessment of catalyst performance is necessary for process design in order to evaluate the effect of reaction conditions on process economics and configuration. In this work, the combined effect of reaction conditions and quality of feedstock (i.e. water content) on the performance of a Hf-Zn catalyst, prepared by physically mixing the zinc silicate hemimorphite and HfO2/SiO2, for the conversion of ethanol to 1,3-butadiene is investigated. To this aim, an experimental design was performed with temperature, space velocity, and water content in ethanol as factors. In situ IR spectroscopy unambiguously indicates that the presence of water in the ethanol feed induces the generation of new Brønsted acid sites, most probably by reaction of Zn2+ Lewis acid sites with water, and thus modifies the Brønsted-Lewis acid site balance in the catalyst. This fact results in (i) higher selectivity to dehydration products catalyzed by Brønsted acid sites, and (ii) lower ethanol conversion as some Zn2+ Lewis acid sites, active for the dehydrogenation of ethanol, are transformed into Brønsted acid sites. In addition, higher acetaldehyde yield is observed in experiments feeding hydrous ethanol, indicating that water inhibits aldol condensation reactions to a larger degree than ethanol dehydrogenation. This effect is particularly beneficial at a high operating temperature, where acetaldehyde is so reactive that it is rapidly converted to heavy compounds unless water is present. Therefore, the benefits of water in ethanol under such reacting conditions should lead to savings in operating costs for the energy-intensive removal of water from ethanol and the use of a cheaper ethanol feedstock with high water content.

Role of small addition of liquefied petroleum gas (LPG) on laminar burning velocity of hydrous ethanol

Ethanol is an appropriate substitution for gasoline fuel in spark ignition engines. Ethanol has a high-octane number allowing to use it in the higher compression ratio of the engine. A better understanding of combustion characteristics of ethanol is needed before it is used widely in the spark ignition engine. One of the most important parameters of the replacement fuel is the burning velocity. Therefore, the purpose of the research is to investigate experimentally the effect of the small addition of liquefied petroleum gas (LPG) on the laminar burning velocity of hydrous ethanol. The combustion characteristic of the ethanol and LPG mixture was examined in a cylindrical combustion chamber with a diameter of 10.8 cm and a length of 17 cm. The flame had a spherically expanding shape. Fuel mixture was ignited by sparks inside the cylinder and the flame diameter was measured from the flame image captured by the high-speed camera. The research used two types of ethanol fuel such as anhydrous ethanol and hydrous ethanol containing 0.3 % of water. The percentage of LPG in the fuel mixture was varied from 0 % to 20 %. The results showed that the addition of 10 % LPG in ethanol increases laminar burning velocity. For anhydrous fuels, ethanol burning velocity is higher than for LPG and the highest burning velocity is in ethanol, to which 10 % LPG is added while the lowest is in LPG. Besides, the effect of water content in ethanol fuel causes a decrease in combustion speed significantly. But the addition of LPG up to 10 % makes hydrous ethanol relatively more robust to rising water content due to the combustion reaction is helped by a higher radical concentration in LPG. This is caused by two factors: the partial preheating zone resulted by the hydroxyl group (OH) of ethanol that supplied more heat energy and the high concentration of radicals in LPG that assists the combustion reaction.

Determination of Water Content in Bioethanol Using the 1H NMR Chemical Shift Change

Chemical shift change in 1H NMR spectroscopy was used to determine water content in bioethanol. As water content in ethanol is increased, the proton peaks shifted to down‐field due to the change in the microstructure of the water‐ethanol mixture. The linear correlation between water content and chemical shift change enables the evaluation of water content in bioethanol. Because the same relationship between chemical shift change and the water content is obtained for both ethanol and bioethanol, water content in bioethanol can be determined using the calibration curve obtained with anhydrous ethanol. The developed method was validated by comparison to the results of Karl Fischer titration and was applied to commercially available bioethanols.

Contactless Optical Fiber Interferometric Sensor to Monitor Water Content in Ethanol

A simple contactless optical fiber interferometric sensor for real-time measurement of low-level of water content in ethanol is proposed and demonstrated. The sensing head consists of a multi-cavity Fabry–Perot interferometer formed with a fiber tip in close contact with a quartz spectrophotometer cell. Ethanol–water solutions introduced into the cell cavity produce a change in the optical path length of one cavity of the interferometer. The increment of water content induces refractive index changes, but more important the absorption of the light increases. Both effects produce a significant change in the interference spectra that can be easily monitored and quantified in the Fourier domain. We demonstrate that our technique can detect water content (0%–60%) in ethanol with a detection limit as low as 0.5%.

Polycrystalline Boron-doped Diamond Electrolyte-solution-gate Field-effect Transistor Applied to the Measurement of Water Percentage in Ethanol

A polycrystalline diamond electrolyte-solution-gate field-effect transistor (BDD-SGFET) was successfully applied to the analysis of water content in ethanol. Due to the use of a no-gate-insulator FET, the developed sensor showed a four-times-faster response than the conventional Si-FET, and a ten-times-faster response than a glass electrode. The output voltage showed good linearity with respect to the water content. This result is of practical importance because the traditional water content measurement methods are impractical due to their slow response.

Characterization of a spherical heat source for measuring thermal conductivity and water content of ethanol and water mixtures

The study and the development of measuring methods of thermal conductivity are essential in several engineering applications, since as a consequence of the current justified demands on saving and rational use of thermal energy, the heat transfer with the maximum efficient as possible is of great relevance. The measurement of the water content is also a relevant parameter in several research areas and industrial sectors, since the quantity of water in the substances influences several biological, chemical and physical processes. The aim of this paper is to present an experimental and theoretical study, following the good metrological practices, of a method based on a spherical heat source in order to measure the thermal conductivity of liquids, focusing on water, ethanol and their mixtures, with later determination of the water content of the binary samples.

Bilayers directly scrolling up to form nanotubes via self-assembly of an achiral small molecule.

The self-assembly behavior of a molecule composed of an azobenzene segment, carboxylic-acid group and flexible alkyl chains (denoted by ABA11) was studied as an extension of our proceeding work. We have previously reported that in DMSO solution ABA11 self-assembled into nanotubes starting from nanosheets and experiencing a meta-state of helical ribbons. Herein, we found that changing the solvent can also affect the self-assembly pathway of ABA11 to nanotubes. When DMSO was replaced by ethanol, the nanosheets formed by ABA11 bilayers either directly scrolled up to form nanotubes without a meta-state of helical ribbons at low concentrations, or stacked up to form nanobricks at higher concentrations. In addition, increasing the water content in ethanol can significantly facilitate the formation of the assembled nanostructures.

Dual signaling of water contents of biofuel-relevant ethanol and butanol by pyranines

Novel optical sensors for measuring the water contents of biofuel-relevant ethanol and 1-butanol based on the pyranine fluorophore were investigated. The diethylsulfonamide derivative of pyranine showed a pronounced absorption and fluorescent signaling in response to changes in the water content of ethanol and 1-butanol. This signaling was based on the increased dissociation of the acidic hydroxy group of pyranine in response to the increasing water content of the alcohol solutions. The signaling behavior of the sensors was readily analyzed by ratiometric measurements using the absorption and fluorescence characteristics of the undissociated and dissociated forms. Upon the derivatization to diethylsulfonamide, the signaling became more sensitive than that for its parent pyranine. The detection limits of the pyranine and diethylsulfonamide derivative for the measurement of the water content in ethanol were 1.9% and 0.03%, respectively. On the other hand, the detection limit of the diethylsulfonamide derivative for the determination of the water content in 1-butanol was 0.01%, whereas underivatized pyranine was not useful because of the limited solubility of the sensor. The practical application of this method for measuring the water content in ethanol and 1-butanol using a smartphone as an easy-to-use signal capturing device was also explored.

The use of an e-tongue for discriminating ethanol/water mixtures and determination of their water content

This paper discusses the applicability of an electronic tongue (e-tongue) based on capacitance measurements to determine the water content in ethanol. The e-tongue consisted of an array of interdigitated electrodes coated with ultrathin films of gallium nitrate and titanium dioxide, which were robust against attack by ethanol. Principal Component Analysis (PCA) was used to treat the capacitance data for discriminating ethanol/water mixtures even in cases with very small water contents. Discrimination is easier if the water added to ethanol contains ions, as is the case of tap water or if NaCl is added to the mixtures. With this e-tongue we were able to quantify the water content through a linear relationship between the first principal component (PC1) and the added water to the biofuel. Therefore, we have proven to be possible to measure the water content precisely, which is one of the major problems in ethanol biofuel adulteration nowadays.

In-Line Measurement of Water Contents in Ethanol Using a Zeolite-Coated Quartz Crystal Microbalance.

A quartz crystal microbalance (QCM) was utilized to measure the water content in ethanol. For the improvement of measurement sensitivity, the QCM was modified by applying zeolite particles on the surface with poly(methyl methacrylate) (PMMA) binder. The measurement performance was examined with ethanol of 1% to 5% water content in circulation. The experimental results showed that the frequency drop of the QCM was related with the water content though there was some deviation. The sensitivity of the zeolite-coated QCM was sufficient to be implemented in water content determination, and a higher ratio of silicon to aluminum in the molecular structure of the zeolite gave better performance. The coated surface was inspected by microscopy to show the distribution of zeolite particles and PMMA spread.

Titania Nanoparticle Film Prepared by Electrophoretic Deposition under DC Constant-Current Condition

Electrophoretic deposition (EPD) is one of useful methods for the preparation of the thin film with homogeneous microstructure on a conductive substrate. In the EPD method, the structure of the particle thin film could be controlled by adjusting the electrical operating conditions. Titania nanoparticle (NP) films, which are used for the electrode of dye-sensitized solar cells (DSSCs), require not only the homogeneous microstructure but also controlled pore size distribution, contributing to high-rate transport of electrons for the high conversion efficiency of DSSCs. In this study, titania NP films were prepared by EPD under DC constant-current conditions using available NPs dispersed in ethanol. The thickness as well as the weight of the titania NP film appeared to be increased almost linearly with EPD operation time, while the porosity of the film calculated from those values was not always constant but increased slightly with the operation time and asymptotically reached about 60%. We confirmed that the forces on the particles depositing onto the substrate became weaker as the EPD operation time increased, due to the electrostatic charges gradually building up on the thin NP film with particle deposition. The deposition behavior of titania NPs was drastically changed upon varying the water content in ethanol. We detected many pinholes on the surface of thin NP films when the water content in ethanol increased. The amount of particles accumulated on the substrate via EPD could be calculated based on the electrical conductivity of the suspension and the mobility of particles in the suspension, but was found to be underestimated when the water content increased.

Water content in hydrated ethanol fuel measured by a photothermal chamber with a transparent transducer

Abstract A photothermal chamber with a transparent transducer and a 1450 nm laser were used to measure the water content of hydrated ethanol biofuel. The values of water content in the fuel samples assessed using the photothermal chamber were compared with reference values certified by Karl-Fischer titration. The results indicate good agreement between these two methodologies. Detection thresholds of 0.73 and 0.89 (% w/w) and sensitivity of 0.039 and 0.014 mV/(% w/w) were assessed at the laser powers of 340 and 125 mW, respectively. This study proves that the analytical approach based on the photothermal chamber with a transparent transducer is convenient to determine the water content in ethanol fuel because it is capable of providing reliable results in a quick and accurate way.

Effect of Operating Parameters on Ethanol–Water Vacuum Separation in an Ethanol Dehydration Apparatus and Process Modeling with ANN

Abstract Bioethanol has been found to be a suitable substitute for gasoline in internal combustion engines. It could be used either in an undiluted form or blended with gasoline. To blend the ethanol and gasoline, the water content of ethanol should reach 0.5% or less. In the present research work, 3A Zeolite was used as an absorbent with vacuum distillation. The effects of the operating parameters such as temperature, vacuum pressure and vapor flow rate on ethanol–water separation were investigated. Final ethanol concentration was obtained at the end of every run as well as the concentration of outlet ethanol. Both linear regression and ANN design were used to determine the best fit for two final parameters. The optimum condition was obtained at 0.4 bar vacuum pressure and 20 l/min ethanol–water vapor flow rate. ANN model is more qualified to the simulation of outspread data while the linear regression is not. L10L10 mode and L5T10 mode provide the best results for final concentration and total time, respectively. The Trainlm Algorithm like the previous research training algorithm is the best.

Flammability limits of hydrated and anhydrous ethanol at reduced pressures in aeronautical applications

There is interest in finding the flammability limits of ethanol at reduced pressures for the future use of this biofuel in aeronautical applications taking into account typical commercial aviation altitude (<40,000ft). The lower and upper flammability limits (LFL and UFL, respectively) for hydrated ethanol and anhydrous ethanol (92.6% and 99.5% p/p, respectively) were determined for a pressure of 101.3kPa at temperatures between 0 and 200°C. A heating chamber with a spherical 20-l vessel was used. First, LFL and the UFL were determined as functions of temperature and atmospheric pressure to compare results with data published in the scientific literature. Second, after checking the veracity of the data obtained for standard atmospheric pressure, the work proceeded with reduced pressures in the same temperature range. 295 experiments were carried out in total; the first 80 were to calibrate the heating chamber and compare the results with those given in the published scientific literature. 215 experiments were performed both at atmospheric and reduced pressures. The results had a correlation with the values obtained for the LFL, but values for the UFL had some differences. With respect to the water content in ethanol, it was shown that the water vapor contained in the fuel can act as an inert substance, narrowing flammability.

In-Line Measurement of Water Content in Ethanol Using a PVA-Coated Quartz Crystal Microbalance

An in-line device for measuring the water content in ethanol was developed using a polyvinyl alcohol (PVA)-coated quartz crystal microbalance. Bio-ethanol is widely used as the replacement of gasoline, and its water content is a key component of its specifications. When the PVA-coated quartz crystal microbalance is contacted with ethanol containing a small amount of water, the water is absorbed into the PVA increasing the load on the microbalance surface to cause a frequency drop. The determination performance of the PVA-coated microbalance is examined by measuring the frequency decreases in ethanol containing 2% to 10% water while the ethanol flows through the measurement device. The measurements indicates that the higher water content is the more the frequency reduction is, though some deviation in the measurements is observed. This indicates that the frequency measurement of an unknown concentration of water in ethanol can be used to determine the water content in ethanol. The PVA coating is examined by microscopy and FTIR (Fourier transform infrared) spectroscopy.

A fluorescent probe for water content in ethanol based on a complex of ruthenium(ii)

A new fluorescent dye, a complex of ruthenium(II), Ru(NH2-phen)3Cl2, using 5-amino-1,10-phenanthrolin (NH2-phen) as a ligand reagent was synthesized by simple steps and its application for water content determination in ethanol was described. The fluorescence intensity of the probe decreased obviously with increasing water content in ethanol when it was excited at 322 nm. The probe showed a linear response toward water content in the concentration range ca. 0.50–7.00%. Additionally, the prepared sensing system was insensitive to oxygen and ionic strength and presented satisfactory sensitivity. The detection limit could be as low as 0.035%.

A simple and fast procedure for in situ determination 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.

Quantification of water in ethanol using a photothermal transparent transducer

Ethanol with added water may be found during the process of assessing its physical and chemical properties. This addition can damage automotive vehicle engines and also may contribute to tax evasion. The present contribution describes a method based on a photothermal transparent transducer to determine the water content in ethanol. A chamber with a window of lithium tantalate coated with a thin layer of indium tin oxide was used, and a 1450-nm laser diode was employed as the excitation source. The results indicated a nearly linear response of the apparatus, as a function of the water content in water/ethanol solutions ranging from 0 to 100 (vol.%). The results for the dependency of the photothermal signal on the laser power and chopping frequency suggested that reliable results can be obtained using laser power and chopping rates above 100mW and 10Hz, respectively. The results reported here may be useful in the development of an alternative method that can provide real-time data on the water concentration in ethanol in a rapid, portable and unambiguous way, and that can be easily used in laboratory analyses or in gas stations.