Ethanol Concentration In Water Research Articles

Unraveling the Surface Activity of Ethanol-Water Mixtures through Experiments and Molecular Dynamics Simulations.

Ethanol's complete miscibility in water makes it a widely used solvent in various applications, such as organic compound synthesis, paint manufacture, chromatography, and cosmetics preservation. Studies suggest that ethanol's concentration at interfaces can be higher than in the bulk due to its amphiphilic nature, especially at lower concentrations, making it a surface-active agent. Accordingly, ethanol plays a crucial role in controlling the emulsion stability, foam formation, heat transfer, and coating adhesion. However, the precise concentration ranges up to which ethanol's surface activity dominates its interfacial properties, and the underlying molecular mechanism is not fully understood in the literature. In this context, our foamability experiments, coupled with film stability experiments conducted via ethanol drop impact on varying concentration ethanol-water mixture pools, indicate that the surface-active nature of ethanol is observed up to a maximum of 10% molar ethanol concentration in water. We next employ all-atom molecular dynamics simulations to reveal that the surface tension and other interfacial properties are most significantly affected only up to the molar concentration in the range of 0-10% of ethanol in water. This observation is further supported by free energy analyses, indicating that the stabilization free energy of an ethanol molecule at the interface becomes comparable to that in the bulk region beyond this concentration range. The transition from surface-active to a behavior resembling a homogeneous solution occurs when the molar concentration of ethanol in water exceeds 10%. This transition is attributed to distinctive alterations in the number and strength of ethanol-water hydrogen bonds. These findings provide valuable insights into the interfacial molecular structure, which can be suitably exploited to modulate interfacial properties and dynamic behavior in a wide array of industrial and scientific applications.

Temperature-Compensated Solution Concentration Measurements Using Photonic Crystal Fiber-Tip Sensors.

We demonstrate fiber optic sensors with temperature compensation for the accurate measurement of ethanol concentration in aqueous solutions. The device consists of two photonic crystal (PhC) fiber-tip sensors: one measures the ethanol concentration via refractive index (RI) changes and the other one is isolated from the liquid for the independent measurement of temperature. The probes utilize an optimized PhC design providing a Lorentzian-like, polarization-independent response, enabling a very low imprecision (pm-level) in the wavelength determination. By combining the information from the two probes, it is possible to compensate for the effect that the temperature has on the concentration measurement, obtaining more accurate estimations of the ethanol concentration in a broad range of temperatures. We demonstrate the simultaneous and single-point measurements of temperature and ethanol concentration in water, with sensitivities of 19 pm/°C and ∼53 pm/%, in the ranges of 25 °C to 55 °C and 0 to 50% (at 25 °C), respectively. Moreover, a maximum error of 1.1% in the concentration measurement, with a standard deviation of ≤0.8%, was obtained in the entire temperature range after compensating for the effect of temperature. A limit of detection as low as 0.08% was demonstrated for the concentration measurement in temperature-stable conditions.

Kinetic Extraction of Fucoxanthin from Undaria pinnatifida Using Ethanol as a Solvent.

Fucoxanthin (Fx) has been proven to exert numerous biological properties, which makes it an interesting molecule with diverse industrial applications. In this study, the kinetic behavior of Fx was studied to optimize three variables: time (t-3 min to 7 days), temperature (T-5 to 85 °C), and concentration of ethanol in water (S-50 to 100%, v/v), in order to obtain the best Fx yield from Undaria pinnatifida using conventional heat extraction. The Fx content (Y1) was found through HPLC-DAD and expressed in µg Fx/g of algae sample dry weight (AS dw). Furthermore, extraction yield (Y2) was also found through dry weight analysis and was expressed in mg extract (E)/g AS dw. The purity of the extracts (Y3) was found and expressed in mg Fx/g E dw. The optimal conditions selected for Y1 were T = 45 °C, S = 70%, and t = 66 min, obtaining ~5.24 mg Fx/g AS; for Y2 were T = 65 °C, S = 60%, and t = ~10 min, obtaining ~450 mg E/g AS; and for Y3 were T = 45 °C, S = 70%, and t = 45 min, obtaining ~12.3 mg Fx/g E. In addition, for the selected optimums, a full screening of pigments was performed by HPLC-DAD, while phenolics and flavonoids were quantified by spectrophotometric techniques and several biological properties were evaluated (namely, antioxidant, antimicrobial, and cholinesterase inhibitory activity). These results could be of interest for future applications in the food, cosmetic, or pharmaceutical industries, as they show the Fx kinetic behavior and could help reduce costs associated with energy and solvent consumption while maximizing the extraction yields.

Microstrip Copper Nanowires Antenna Array for Connected Microwave Liquid Sensors

In this contribution, a 25 GHz planar antenna, designed and realized in microstrip technology, is exploited as a lightweight and compact liquid sensor. The high working frequency allows minimization of the sensor dimension. Moreover, particular attention was paid to keeping the design cost low. Indeed, the frequency of 25 GHz is widely exploited for many applications, e.g., up to the last decade concerning radars and, recently, 5G technology. Available commercial antennas allowed minimization of the effort that is usually required to design the microstrip sensor. The antenna was in-house realized, and the microstrip Cu conductor was modified through controlled anodic oxidation in order to enhance the sensing features. The sensor capability of detecting the presence and concentration of ethanol in water was experimentally demonstrated. In detail, a sensitivity of 0.21 kHz/(mg/L) and an average quality factor of 117 were achieved in a very compact size, i.e., 18 mm × 19 mm, and in a cost-effective way. As a matter of fact, the availability of devices able to collect data and then to send the related information wirelessly to a remote receiver represents a key feature for the next generation of connected smart sensors.

The Impact of Acetic Acid on Measuring Ethanol Concentrations in Water and Human Serum Using Short-Wave Infrared Spectroscopy.

Ethanol intoxication, although an elemental part of life in many places around the world, still presents several issues associated with excessive consumption. These issues range from drunk driving, violence, and antisocial behavior to self-harm, all exerting an increased cost on the society. Monitoring of intoxication levels can help to limit the impact of these issues by preventing the use of automobiles or heavy machinery and personal monitoring. Previous works on noninvasive measurement of ethanol tissue concentration for estimation of blood alcohol concentration (BAC) performed worst during the first hour of intoxication. Gas chromatography research of intoxication shows that levels of acetic acid rise together at a similar rate as those of ethanol after initial imbibement. In this research, short-wave infrared (SWIR) spectroscopy was utilized with the aim of establishing the interaction between ethanol and acetic acid in water and serum mixtures. The most consistent and clear correlation between ethanol and acetic acid was recorded at 2262 and 2302 nm wavelengths. Partial least-squares (PLS) analysis indicates that the most effective region for consideration in measurement of ethanol is the therapeutic window four (IV) due to high variance in vibration of carbon bonds. The behavior of spectra at different concentration ranges was examined and described in detail in relation to the consequence of alcohol measurement. The investigation concluded that ethanol shows distinctive regions of absorbance at wavelengths of 2262 and 2302 nm, with variations arising from increasing concentrations of acetic acid, whilst also showing that therapeutic window four is amongst the most influential regions of the spectrum for SWIR.

Spectral sensor of the ethanol concentration in water based on photodiode optoelectronic chromatic dispersion.

Optoelectronic chromatic dispersion (OED) of a PN-type germanium photodiode is used for spectral sensing of ethanol concentration in water. A concentration sensitivity of 70 ppm is achieved. Spectral sensors based on OED in PN-type photodiodes can serve as low-cost on-chip devices for optical spectroscopy.

A microwave-based extraction method for the determination of sugar and polyols: Application to the characterization of regular and peaberry coffees

The brewing properties of coffee products are defined by the chemical composition in the bean, including sugars and polyols. Some factors, such as coffee species and roasting, may affect the level of these compounds in the bean. A new analytical microwave-assisted extraction (MAE) method has been developed to extract sugars and polyols from the coffee bean. The studied extraction conditions for the MAE were temperature (30–80 °C), solvent composition (0–50% ethanol in water), and solvent-to-sample ratio (10:1–30:1 mL solvent per g sample). A Box-Behnken design was applied to study the effect of extraction variables, and subsequently, the influential variables were optimized by response surface methodology (RSM). In addition to the main effect of the solvent-to-sample ratio, all quadratic effects significantly influenced ( p < 0.05) the recovery of sugars and polyols from the coffee beans. RSM suggested the optimized MAE conditions: temperature 52 °C, ethanol concentration in water 18.5%, and solvent-to-sample ratio 17:1. Under the optimum condition, a kinetics study confirmed that 15 min showed high precision and accuracy of the developed method. Ultimately, a real sample application of the developed MAE revealed that the new method successfully described the composition of sugars and polyols in regular and peaberry coffee beans. Additionally, the method also effectively characterized the green and roasted Arabica and Robusta coffee beans.

Correlation of the GC-MS-based metabolite profile of Momordica charantia fruit and its antioxidant activity

Momordica charantia or bitter melon (Cucurbitaceae) is a widely consumed edible fruit with strong antioxidant properties. Due to these properties, it has been commercialised by the natural product industries as a coadjutant in the treatment of various ailments attributable to the deleterious effects of oxidants. The present work aimed to evaluate the antioxidant activity of M. charantia fruit extracts made with different compositions of ethanol:water, and to identify the metabolites that are responsible for this activity. To this end, the fruit samples were extracted using six different concentrations of ethanol in water (0, 20, 40, 60, 80, and 100%). Gas chromatography-mass spectrometry (GC-MS) and multivariate data analysis (MVDA) were used to identify significant antioxidants. The 80% ethanol:water extract showed the most significant (p &lt; 0.05) antioxidant activity when tested with the 1, 1-diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) antioxidant assays. The multivariate data analysis revealed that the metabolites related to this antioxidant activity were gentiobiose, glucose, galactonic acid, palmitic acid, galactose, mannose, and fructose.

Design and evaluation of non-conventional extraction for bioactive compounds recovery from spent coffee (Coffea arabica L.) grounds

Spent coffee grounds are one of the most interesting waste streams of coffee industry containing antioxidants, whose extraction may represent an innovative solution for the reduction of the environmental burden of this waste, simultaneously providing high added value compounds. The aim of this work was to valorize SCG (Coffea arabica L.) using a non-conventional technique (high pressure and temperature extraction), by providing pivotal information and experimental data essential for the design of a profitable and green process. A 3-level factorial design was firstly employed to verify the combined effects of ethanol concentration in water, used as solvent, and temperature on total polyphenol yield and antiradical power of the extract. Desirability method was used to estimate the optimal conditions (ethanol 50% (v/v) as solvent at 150°C), allowing the recovery of remarkable amount of bioactive compounds (30.4±1.7mg/100mL of chlorogenic acid and 31.7±2.9mg/100mL of caffeine). Moreover, Peleg's model was successfully applied to describe extraction kinetic, showing that an extraction time of 60min is sufficient to produce extracts with high extraction yields (43±0.8mg caffeic acid equivalents/g dried biomass) and remarkable antiradical properties (734±11μg trolox equivalents/g dried biomass).

Long-lasting implications of embryonic exposure to alcohol: Insights from zebrafish research.

The harmful consumption of ethanol is associated with significant health problems and social burdens. This drug activates a complex network of reward mechanisms and habit formation learning that is supposed to contribute to the consumption of increasingly high and frequent amounts, ultimately leading to addiction. In the context of fetal alcohol spectrum disorders, fetal alcohol syndrome (FAS) is a consequence of the harmful use of alcohol during pregnancy, which affects the embryonic development of the fetus. FAS can be easily reproduced in zebrafish by exposing the embryos to different concentrations of ethanol in water. In this regard, the aim of the present review is to discuss the late pathological implications in zebrafish exposed to ethanol at the embryonic stage, providing information in the context of human fetal alcoholic spectrum disorders. Experimental FAS in zebrafish is associated with impairments in the metabolic, morphological, neurochemical, behavioral, and cognitive domains. Many of the pathways that are affected by ethanol in zebrafish have at least one ortholog in humans, collaborating with the wider adoption of zebrafish in studies on alcohol disorders. In fact, zebrafish present validities required for the study of these conditions, which contributes to the use of this species in research, in addition to studies with rodents.

An experimental FTIR-ATR and computational study of H-bonding in ethanol/water mixtures

• FTIR-ATR spectra show that certain peaks shift as a function of concentration of ethanol in water. • A cyclic H-bonded network can explain the strong IR shift of the peaks corresponding to the H 2 O bending. • Molecular mechanics calculations support the formation of a cyclic cage-like H-bonded network. Ethanol/water mixtures have served as a model to study the hydrophobic effect and the formation of clathrate and other cage like water formations around the hydrophobic end of ethanol. We have studied the evolution of FTIR-ATR spectra of ethanol/water mixtures as a function of the content of water in the mixture. The experimental spectra show redshift of primarily the H-O-H bending vibration, which is 18.9 cm −1 in total width. It also shows a blueshift of 9.0 cm −1 of the asymmetric stretching vibration of C-H groups of β-CH 3 . These infrared spectral shifts are consistent with the formation of a cyclic H-bonded network between ethanol and H-bonded water molecules. This hypothesis has been supported by full optimizations of high-level B3LYP/aug-cc-pVQZ calculations in implicit and explicit water and ethanol solvents as well as MMFF94s simulations of ethanol in explicit water clusters with up to 30 water molecules.

CNT-based tapered optical fiber for ethanol remote sensing over 3-km optical fiber

Certain organic liquids like ethanol in water are considered hazardous and have an enormous environmental impact since it is toxic and classified as class I flammable liquids. Remote sensing with complex sensors is a common technique for detecting and tracking spillages of hazardous spillages. Most of the applied remote sensing methods suffer from location and control issues that force the user to be at the exact sensing spot during operation. The present work introduces a simple and highly sensitive tapered multimode optical fiber (TMOF) sensor coated with carbon nanotubes (CNT) for flammable liquids remote sensing applications. The new proposed sensor ability to transfer signals to a remote data collection center of about 3 km from the sensor location was investigated. Ethanol was utilized as the index solution to be tested in the present work. The proposed sensor was attached to 3 km multimode silica optical fiber and characterized towards different concentrations of ethanol in de-ionized water at room temperature. Various characterization techniques have investigated the detailed structural properties of the sensing layer. The experimental results demonstrated that the proposed remote sensor exhibits rapid response with recovery times of 8.7 s and 18 s, respectively, and relative absorbance of 26% upon exposure to 100% ethanol. The sensor attains an overall sensitivity of 1.3/vol% towards low ethanol concentrations in water (0.01–0.5%). Besides, the optical sensor manifests outstanding repeatability when exposed to another cycle of ethanol with concentrations of 20% and 40% in de-ionized water. The proposed optical remote sensor's superior performance via low cost and simple techniques indicates its high efficiency for ethanol detection in various industrial applications.

Effect of Pure and Binary Azeotropic Fluids on Heat Pipes Performance

Azeotropic fluids are considered to be a beneficial discovery used in various operations involving mechanical performance of machines. It is the thermodynamic property of the fluids to absorb heat and dissipate it. For instance, the addition of alcohols in water may increase the performance of these fluids. The objective of this work was to conduct a comparative study on heat pipe performance with different working fluids. The working fluids chosen for the study were water and pure ethanol. The concentrations of ethanol in water differed between 25% and 95%. The material of heat pipes was copper with a sintered wicks structure. The experimental results revealed that, the evaporator temperature for water was lower than that of the ethanol and its mixture at high heating input. However, the heat transported by the heat pipes of water was considerably greater than that of the heat pipes of ethanol and binary fluids as working fluids.

Selectivity of SO2 and H2S removal by ethanol-treated calcined eggshell at low temperature.

Eggshell is a food waste produced worldwide in substantial amount with very limited recycling activity. In this study, the potential of ethanol-treated calcined eggshell was tested as sorbent for SO2 and H2S. Three variables were selected in the preparation of sorbents via response surface methodology (RSM), i.e., concentration of ethanol in water (50%, 70%, 90%), reaction temperature (20°C, 40°C, 60°C), and contact time (30, 60, 90min). Central composite design (CCD) was used to develop a quadratic model to correlate the operating variables with the adsorption capacity. Analysis of variance (ANOVA) was performed to identify the significant factors of the experimental design. It was found that the reaction temperature during the sorbent preparation was the most significant factor. The optimum preparation conditions using RSM were found at 20°C of reaction temperature with 76.37% of ethanol concentration for 67min of reaction time. The maximum adsorption capacity for the optimized sorbent was found to be 27.75mg/g and 9.55mg/g for SO2 and H2S, respectively. The prepared sorbent was more selective towards SO2 compared with H2S. Moreover, the presence of 40% of relative humidity in the inlet gas further enhanced the adsorption capacity of both gases. The ethanol-treated calcined eggshell was further substantiated by FESEM, BET, FTIR, XRD, and XRF. Results showed potential usage of eggshell as a sorbent for SO2 and H2S gases.

Whole extract optimization of Adhatoda vasica, Nees leaf by using Response Surface Methodology (RSM)

Present work aimed at optimization of extraction process for various factors to get maximum extract yield for a drug, Adusa (leaf of Adhatoda vasica Nees). The drug is used in the form of powders or decoctions, so Soxhlet apparatus (hot percolation) was used to optimize the yield percentage. Adusa leaf was subjected to extraction process using Soxhlet apparatus. Response surface methodology (RSM) was used to design the number of random runs of the extracts for the drug with variation in the factors of temperature, concentration of ethanol in water, time for extraction for maximizing the yield concentration. The data thus obtained was analyzed for optimization for yield maximization. Minitab version 18 was used to design and analyze the data. Validation of the optimum conditions for maximum yield of the extract of Adusa leaf was carried out by re-run of the extract using optimum conditions and measuring the yield. The study showed that optimum condition for extracting Adusa leaf for temperature, solvent concentration, and time for extraction was 800C, 48.18% and 8 h respectively. Adusa leaf extract gave maximum yield of 22.07%. The optimum factors when reemployed yielded 23.73% of the extract validating the methodology. RSM used in present study is cheap and affordable method to optimize maximum yield% which may be reliably used by researchers for research in this area.

Extraction and identification by mass spectrometry of phenolic compounds from canola seed cake.

Canola oil processing generates as by-products cakes rich in proteins, which have high nutritional value. These cakes contain an expressive amount of phenolic compounds which are important as antioxidants, but can interfere in proteins nutritional value. The aim of this work was to identify the phenolic compounds present in canola seed cake and to maximize their extraction by investigating the factors: temperature (20-70 °C), ethanol concentration in water (0-85%) and sample/solvent ratio (1:5-1:20). The maximum phenolic compounds amount was obtained at 65 °C, ethanol concentration of 35% and sample/solvent ratio of 1:20. At this condition, more than 95% of these compounds were extracted from the canola seed cake. It was observed that the solvent could be re-used for additional extractions, reducing the solvent consumption. A large number of phenolic compounds were identified (24 compounds) and quantified, including sinapic acid derivatives, flavonoid glycosides derivatives and major and minor sinapoyl choline derivatives. The phenolic compounds can be easily extracted from the canola seed cake, resulting in a cake with low antinutrients content and, in contrast, an extract rich in antioxidant compounds with possible use as a natural source of antioxidants. © 2019 Society of Chemical Industry.

Valorization of Wheat Bran: Ferulic Acid Recovery Using Pressurized Aqueous Ethanol Solutions

The extraction of ferulic acid (FA) and other phenolic compounds from wheat bran can represent an interesting valorization step of this lignocellulosic biomass. In this work, pressurized hot water (PHW) and pressurized aqueous ethanol are used as solvents, and the amount of extracted FA in its free form and the total phenolic content of the extract have been evaluated. Total ferulic acid in the initial wheat bran was 2570.9 ± 1.8 µg/g of dry bran, being more than 98.5% esterified to arabinoxylans and other cell wall structures (insoluble-bound FA). Different concentrations of ethanol in water (0–20–50–80%), temperatures (130–145–160 °C) and extraction times (20–40–60 min) were tested. It was observed that low ethanol concentrations in the solvent, high temperatures and long extraction times favored the extraction, being the hydrolysis and not the solvolysis the reaction mechanism involved in the release of bound FA. Maximum FA extraction yield was found for pure water (PHW), 160 °C and 74 min of extraction that corresponds to a thermal severity factor of log (R0) ≈ 3.7. The so obtained FA extraction yields are higher than those obtained with an enzymatic hydrolysis treatment performed for comparison.

Detection of Ethanol Concentration using a Generic Optical Sensor Platform

In this work we introduce a novel and viable model for the measurement of ethanol concentration in water. The concept relies on the optical high spectral sensitivity of plasmonic devices. The ethanol in water mixture shows a linear ratio with the refractive index and the concentration percentage on a selected range of 0 to 45%. The proposed model is based on the refractive index linear relationships of the ethanol concentration and the plasmonic resonance wavelength. Therefore enabling the indirect measurement of the ethanol concentration through the plasmonic resonance wavelength.

Condensate retention of water-ethanol mixture on horizontal enhanced condensing tubes

Condensate retention has been found an important parameter for heat transfer on horizontal enhanced condensing tubes. In this research, five pin-fin (varying in circumferential pin spacing) and three integral-fin horizontal tubes are investigated for condensate retention angle (which is measured from the top of tooth to the fully flooded flank) using water-ethanol mixture. An attempt was made to find the optimum concentration of ethanol in water for maximum retention angle. Concentration of ethanol was varied in between 0.5% to 1.5% by weight. Data revealed the importance of integral-fin tube over pin-fin tube as significant increase in retention angle was observed for integral-fin tube ((having same longitudinal spacing, tooth thickness, tooth height, inner and outer diameter) while retention angle for pin-fin tubes remain unchanged. Optimum ethanol concentration was observed to be 0.75%.

Increased bio-oil yield from Nannochloropsis salina through tuning the polarity of subcritical water

Changing solvent polarity at subcritical conditions, by an appropriate co-solvent, may be used to enhance oil extraction from different raw materials. As a newly commercially interested process, oil extraction from Nannochloropsis salina as a valuable bio-resource, by subcritical water-ethanol mixture as a polarity altered solvent, was investigated. Response surface methodology (RSM) was applied to achieve the best operating conditions. Three factors including temperature (90–150 °C), water-ethanol concentration (25–75 wt%) and flow rate (1.0–4.0 ml/min) were investigated. The best separation conditions were determined at 90 °C, 75 wt% ethanol and 4 ml/min. The oil composition was compared with four other methods including subcritical water extraction (SCWE), ultrasound-assisted extraction (UAE), Soxhlet (SOX) and Folch methods. The main fatty acids were identified as C16:0, C18:0, C18:1c and C18:3c. The highest extraction efficiency of 33.93 wt% was achieved for subcritical water/ethanol mixture.