Separation of ethanol—water mixtures by pervaporation through thin,composite membranes

This paper reports on the separation of ethanol—water mixtures using pervaporation for several membrane types. The FT30 and RC100 membranes pass ethanol selectively at feed concentrations similar to fermentation beers, and the FT30 membrane continues to pass ethanol selectively at higher ethanol feed concentrations. As the ethanol concentration in the feed increases, the ethanol selectivity of both the FT30 and RC100 membranes decreases; near the ethanol—water azeotrope, both membranes pass water selectively. At lower ethanol concentrations, the selectivity of the FT30 membrane increases as the feed temperature increases above 23°C.     

Bioethanol Production from Uncooked Raw Starch by Immobilized Surface-engineered Yeast Cells

Surface-engineered yeast Saccharomyces cerevisiae codisplaying Rhizopus oryzae glucoamylase and Streptococcus bovis α-amylase on the cell surface was used for direct production of ethanol from uncooked raw starch. By using 50 g/L cells during batch fermentation, ethanol concentration could reach 53 g/L in 7 days. During repeated batch fermentation, the production of ethanol could be maintained for seven consecutive cycles. For cells immobilized in loofa sponge, the concentration of ethanol could reach 42 g/L in 3 days in a circulating packed-bed bioreactor. However, the production of ethanol stopped thereafter because of limited contact between cells and starch. The bioreactor could be operated for repeated batch production of ethanol, but ethanol concentration dropped to 55% of its initial value after five cycles because of a decrease in cell mass and cell viability in the bioreactor. Adding cells to the bioreactor could partially restore ethanol production to 75% of its initial value.     

Optimized Fed-Batch Fermentation of Scheffersomyces stipitis for Efficient Production of Ethanol from Hexoses and Pentoses

Scheffersomyces stipitis was cultivated in an optimized, controlled fed-batch fermentation for production of ethanol from glucose–xylose mixture. Effect of feed medium composition was investigated on sugar utilization and ethanol production. Studying influence of specific cell growth rate on ethanol fermentation performance showed the carbon flow towards ethanol synthesis decreased with increasing cell growth rate. The optimum specific growth rate to achieve efficient ethanol production performance from a glucose-xylose mixture existed at 0.1 h^?1. With these optimized feed medium and cell growth rate, a kinetic model has been utilized to avoid overflow metabolism as well as to ensure a balanced feeding of nutrient substrate in fed-batch system. Fed-batch culture with feeding profile designed based on the model resulted in high titer, yield, and productivity of ethanol compared with batch cultures. The maximal ethanol concentration was 40.7 g/L. The yield and productivity of ethanol production in the optimized fed-batch culture was 1.3 and 2 times higher than those in batch culture. Thus, higher efficiency ethanol production was achieved in this study through fed-batch process optimization. This strategy may contribute to an improvement of ethanol fermentation from lignocellulosic biomass by S. stipitis on the industrial scale.     

Effect of Water and Ethanol Extracts from Hericium erinaceus Solid-State Fermented Wheat Product on the Protection and Repair of Brain Cells in Zebrafish Embryos

Extracts from Hericium erinaceus can cause neural cells to produce nerve growth factor (NGF) and protect against neuron death. The objective of this study was to evaluate the effects of ethanol and hot water extracts from H. erinaceus solid-state fermented wheat product on the brain cells of zebrafish embryos in both pre-dosing protection mode and post-dosing repair mode. The results showed that 1% ethanol could effectively promote zebrafish embryo brain cell death. Both 200 ppm of ethanol and water extracts from H. erinaceus solid-state fermented wheat product protected brain cells and significantly reduced the death of brain cells caused by 1% ethanol treatment in zebrafish. Moreover, the zebrafish embryos were immersed in 1% ethanol for 4 h to cause brain cell damage and were then transferred and soaked in the 200 ppm of ethanol and water extracts from H. erinaceus solid-state fermented wheat product to restore the brain cells damaged by the 1% ethanol. However, the 200 ppm extracts from the unfermented wheat medium had no protective and repairing effects. Moreover, 200 ppm of ethanol and water extracts from H. erinaceus fruiting body had less significant protective and restorative effects on the brain cells of zebrafish embryos. Both the ethanol and hot water extracts from H. erinaceus solid-state fermented wheat product could protect and repair the brain cells of zebrafish embryos damaged by 1% ethanol. Therefore, it has great potential as a raw material for neuroprotective health product.     

Investigation into the structural composition of hydroalcoholic solutions as basis for the development of multiple suppression pulse sequences for NMR measurement of alcoholic beverages

An eight‐fold suppression pulse sequence was recently developed to improve sensitivity in ¹H NMR measurements of alcoholic beverages [Magn. Res. Chem. 2011 (49): 734–739]. To ensure that only one combined hydroxyl peak from water and ethanol appears in the spectrum, adjustment to a certain range of ethanol concentrations was required. To explain this observation, the structure of water–ethanol solutions was studied. Hydroalcoholic solutions showed extreme behavior at 25% vol, 46% vol, and 83% vol ethanol according to ¹H NMR experiments. Near‐infrared spectroscopy confirmed the occurrence of four significant compounds (‘individual’ ethanol and water structures as well as two water–ethanol complexes of defined composition – 1 : 1 and 1 : 3). The successful multiple suppression can be achieved for every kind of alcoholic beverage with different alcoholic strengths, when the final ethanol concentration is adjusted to a range between 25% vol and 46% vol (e.g. using dilution or pure ethanol addition). In this optimum region, an individual ethanol peak was not detected, because the ‘individual’ water structure and the 1 : 1 ethanol–water complex predominate. The nature of molecular association in ethanol–water solutions is essential to elucidate NMR method development for measurement of alcoholic beverages. The presented approach can be used to optimize other NMR suppression protocols for binary water–organic solvent mixtures, where hydrogen bonding plays a dominant role. Copyright © 2014 John Wiley & Sons, Ltd.     

Relationship between the density of supercritical CO<Subscript>2</Subscript> + ethanol binary system and its critical properties

The dependent relation between temperature and pressure of supercritical CO₂+ ethanol binary system under the pressure range from 5 to 10 MPa with the variety of densities and mole fractions of ethanol that range from 0 to 2% was investigated by the static visual method in a constant volume. The critical temperature and pressure were experimentally determined simultaneously. The PTρ figures at different ethanol contents were described based on the determined pressure and temperature data, from which pressure of supercritical CO₂ + ethanol binary system was found to increase linearly with the increasing temperature. P-T lines show certain convergent feature in a specific concentration of ethanol and the convergent points shift to the region of higher temperature and pressure with the increasing ethanol compositions. Furthermore, the effect of density and ethanol concentration on the critical point of CO₂ + ethanol binary system was discussed in details. Critical points increase linearly with the increasing mole fraction of ethanol in specific density and critical points change at different densities. The critical compressibility factors Z_c of supercritical CO₂ + ethanol binary systems at different compositions of ethanol were calculated and Z _c -ρ figure was obtained accordingly. It was found from Z _c -ρ figure that critical compressibility factors of supercritical CO₂ unitary or binary systems decline linearly with the increasing density, by which the critical point can be predicted precisely.     

Kinetics of ethanol production from carob pods extract by immobilizedSaccharomyces cerevisiae cells

Kinetics of ethanol production from carob pods extract by immobilizedS. cerevisiae cells in static and shake flask fermentation have been investigated. Shake flask fermentation proved to be a better fermentation system for the production of ethanol than static fermentation. The optimum values of ethanol concentration, ethanol productivity, ethanol yield, and fermentation efficiency were obtained at pH range 3.5–6.5 and temperature between 30–35°C. A maximum ethanol concentration (65 g/L), ethanol productivity (8.3 g/Lh), ethanol yield (0.44 g/g), and fermentation efficiency (95%) was achieved at an initial sugar concentration of 200, 150, 100, and 200 g/L, respectively. The highest values of specific ethanol production rate and specific sugar uptake rate were obtained at pH 6.5, temperature 40°C, and initial sugar concentration of 100 g/L. Other kinetic parameters, biomass concentration, biomass yield, and specific biomass production rate were maximum at pH 5.5, temperature 30°C, and initial sugar concentration 150 g/L. Under the same fermentation conditions non-sterilized carob pod extract gave higher ethanol concentration than sterilized medium. In repeated batch fermentations, the immobilizedS. cerevisiae cells in Ca-alginate beads retained their ability to produce ethanol for 5 d.     

Improvement of Ethanol Yield from Glycerol via Conversion of Pyruvate to Ethanol in Metabolically Engineered <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

The conversion of low-priced glycerol to higher value products has been proposed as a way to improve the economic viability of the biofuels industry. In a previous study, the conversion of glycerol to ethanol in a metabolically engineered strain of Saccharomyces cerevisiae was accomplished by minimizing the synthesis of glycerol, the main by-product in ethanol fermentation processing. To further improve ethanol production, overexpression of the native genes involved in conversion of pyruvate to ethanol in S. cerevisiae was successfully accomplished. The overexpression of an alcohol dehydrogenase (adh1) and a pyruvate decarboxylase (pdc1) caused an increase in growth rate and glycerol consumption under fermentative conditions, which led to a slight increase of the final ethanol yield. The overall expression of the adh1 and pdc1 genes in the modified strains, combined with the lack of the fps1 and gpd2 genes, resulted in a 1.4-fold increase (about 5.4 g/L ethanol produced) in fps1Δgpd2Δ (pGcyaDak, pGupCas) (about 4.0 g/L ethanol produced). In summary, it is possible to improve the ethanol yield by overexpression of the genes involved in the conversion of pyruvate to ethanol in engineered S. cerevisiae using glycerol as substrate.     

Effect of Agitation Rate on Ethanol Production from Sugar Maple Hemicellulosic Hydrolysate by Pichia stipitis

Concentrated dilute acid hydrolysate was obtained from hot water extracts of Acer saccharum (sugar maple) and was fermented to ethanol by Pichia stipitis in a 1.3-L-benchtop bioreactor. The conditions under which the highest ethanol yield was achieved were when the air flow rate was set to 100?cm³ and the agitation rate was set to 150?rpm resulting in an overall mass transfer coefficient (K _L a) of 0.108?min^?1. A maximum ethanol concentration of 29.7?g/L was achieved after 120?h of fermentation; however, after 90?h of fermentation, the ethanol concentration was only slightly lower at 29.1?g/L with a yield of 0.39?g ethanol per gram of sugar consumed. Using the same air flow rate and adjusting the agitation rate resulted in lower ethanol yields of 0.25?g/g at 50?rpm and 0.30?g/g at 300?rpm. The time it takes to reach the maximum ethanol concentration was also affected by the agitation rate. The ethanol concentration continued to increase even after 130?h of fermentation when the agitation rate was set at 50?rpm, whereas the maximum ethanol concentration was reached after only 68.5?h at 300?rpm.     

Xylose fermentation

The economic impact of conversion of xylose to ethanol for a wood-to-ethanol plant was examined, and the maximum potential reduction in the price of ethanol from utilization of xylose is estimated to be 0.42 per gallon from a base case price of0.42 per gallon from a base case price of 1.65. The sensitivity of the price of ethanol to the yield, ethanol concentration and rate of the xylose fermentation was also examined, and the price of ethanol is most affected by changes in yield and ethanol concentration, with rate of lesser importance. Current performances of various xylose conversion biocatalysts were analyzed, andC. shehatae andP. stipitis appear to be the best yeasts.     

Nearcritical and supercritical ethanol as a benign solvent: polarity and hydrogen-bonding

Nearcritical (NC) and supercritical (SC) ethanol may offer novel media for both chemical reactions and separations as a replacement for environmentally undesirable organic solvents. We investigated the dipolarity/polarizability, hydrogen-bond donating acidity and accepting basicity in terms of Kamlet–Taft solvatochromism parameters π¹, α and β in saturated liquid ethanol from 25 to 225 °C and in gaseous and SC ethanol at 250 °C as a function of pressure. Reichardt’s E_T(30) scale was determined for ethanol under the same conditions. NC and SC ethanol has a wide range of solvent strength, which can be readily and continuously tuned by temperature and pressure. Liquid ethanol becomes nearly nonpolar as the temperature increases towards its critical point. The dipolarity/polarizability for SC ethanol ranges from gas-like to nonpolar liquid-like with increasing pressure. On the other hand, ethanol maintains significant hydrogen-bond donating acidity even under the supercritical conditions at 250 °C and at pressures up to 18.7 MPa. The hydrogen-bond accepting basicity, however, is considerably weakened at elevated temperatures. These well-established solvent parameters greatly improve our understanding of hot compressible ethanol, and allow us to explore the feasibility of using it in a variety of benign processes.     

An Efficient Method of Birch Ethanol Lignin Sulfation with a Sulfaic Acid-Urea Mixture

For the first time, the process of birch ethanol lignin sulfation with a sulfamic acid-urea mixture in a 1,4-dioxane medium was optimized experimentally and numerically. The high yield of the sulfated ethanol lignin (more than 96%) and containing 7.1 and 7.9 wt % of sulfur was produced at process temperatures of 80 and 90 °C for 3 h. The sample with the highest sulfur content (8.1 wt %) was obtained at a temperature of 100 °C for 2 h. The structure and molecular weight distribution of the sulfated birch ethanol lignin was established by FTIR, 2D ¹H and ¹³C NMR spectroscopy, and gel permeation chromatography. The introduction of sulfate groups into the lignin structure was confirmed by FTIR by the appearance of absorption bands characteristic of the vibrations of sulfate group bonds. According to 2D NMR spectroscopy data, both the alcohol and phenolic hydroxyl groups of the ethanol lignin were subjected to sulfation. The sulfated birch ethanol lignin with a weight average molecular weight of 7.6 kDa and a polydispersity index of 1.81 was obtained under the optimum process conditions. Differences in the structure of the phenylpropane units of birch ethanol lignin (syringyl-type predominates) and abies ethanol lignin (guaiacyl-type predominates) was manifested in the fact that the sulfation of the former proceeds more completely at moderate temperatures than the latter. In contrast to sulfated abies ethanol lignin, the sulfated birch ethanol lignin had a bimodal and wider molecular weight distribution, as well as less thermal stability. The introduction of sulfate groups into ethanol lignin reduced its thermal stability.     

The stability of ethanol in stored blood. I. Important variables and interpretation of results

The effects of the factors time, sodium fluoride concentration, ethanol concentration, temperature of storage and type of container on the ethanol losses from stored human blood have been investigated by means of a 2⁵ factorial experiment. The important factors were found to be temperature, fluoride concentration and time of storage. A detailed study of the important factors enabled three distinct mechanisms of ethanol loss to be identified. These were a highly temperature-dependent ethanol oxidation reaction which was independent of the ethanol concentration over a wide range; destruction of ethanol by the action of micro-organisms in the absence of a preservative, which could be inhibited by 0.5% (w/v) sodium fluoride, and diffusion which was found to occur from 5.6% of the polypropylene containers used in Britain for the purposes of the Road Traffic Act 1972.     

Sodium modification of zirconia catalysts for ethanol coupling to 1-butanol

The influences of adding sodium to zirconia on the acid-base properties of the surface and on the catalytic conversion of ethanol and acetone were investigated. The rates of ethanol dehydration, dehydrogenation and coupling were evaluated in a fixed-bed flow reactor operating at temperatures from 613 to 673 K. The rate of acetone condensation was evaluated in the same reactor operating at 473–573 K. Addition of 1.0 wt% Na to ZrO₂ decreased the rate of ethanol dehydration by more than an order of magnitude, which was consistent with a neutralization of acid sites evaluated by ammonia adsorption microcalorimetry. Addition of 1.0 wt% Na to ZrO₂ also increased the base site density quantified by carbon dioxide adsorption microcalorimetry and the rate of acetone condensation. Although the rate of ethanol coupling was not increased by the addition of Na, the overall selectivity of ethanol to butanol was improved over the 1.0 wt% Na/ZrO₂ sample because of the significant inhibition of ethanol dehydration.     

Probing the Interdigitated Phase of a DPPC Lipid Bilayer by Micropipette Aspiration

We used micropipette aspiration of giant unilamellar vesicles to directly measure the areal expansion of gel (L_β′) phase 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) lipid bilayers induced by exposure to ethanol/water mixtures. Areal expansion began in 7 vol% ethanol and increased monotonically as the concentration of ethanol was increased to 15 vol% at which point areal expansion reached a plateau of 50%. This ethanol concentration range is in good agreement with that of the interdigitated phase (L_βI) of DPPC, therefore, we believe that this is the first direct measurement of the areal expansion accompanying interdigitation of gel-phase lipids. Our observations are consistent with the presence of coexisting L_βI and L_β′ phases in ethanol concentrations between 7% and 15 vol% and 100% L_βI phase in 15 vol% ethanol and higher. We observed a bimodal distribution of areal expansion (0% and 20%) induced by 7 vol% ethanol indicating that at the threshold concentration, interdigitation is induced in only a portion of DPPC vesicles. Areal expansion could not be easily reversed, consistent with kinetic trapping of the L_βI phase. DPPC vesicles exposed to butanol at the known threshold and plateau concentrations for the L_βI phase displayed areal expansion behavior consistent with our ethanol observations. However, the area expanded significantly faster for DPPC bilayers exposed to butanol vs. ethanol, which we attribute to enhanced partitioning of the longer-chained butanol into the lipid headgroups. Ethanol-induced areal expansion of DPPC bilayers was inhibited by inclusion of 10 mol% and 25 mol% cholesterol in the bilayer. However, areal expansion could be induced by application of tensions (∼8 mN/m) similar to the phenomena of interdigitation induced by high pressure. The presence of 20 vol% ethanol significantly decreased surface cohesion of DPPC bilayers containing 25 mol% cholesterol as evidenced by a decreased area compressibility modulus and lysis tension.     

Hydrogenolysis of benzofuran using aqueous ethanol solution over graphite-supported platinum catalyst

Graphite-supported platinum catalysts (Pt/G) were highly active for the hydrogenolysis of benzofuran to o-ethylphenol in aqueous ethanol solution at 523 K without using any external hydrogen gas. The hydrogenolysis activities and selectivity to o-ethylphenol in ethanol solution over Pt/G were higher than those with a conventional method using externally supplied hydrogen gas. Both water and ethanol were indispensable for the hydrogenolysis in aqueous ethanol solution at 523 K.     

Alcohol Selective Optical Sensor Based on Porous Cholesteric Liquid Crystal Polymer Networks

A responsive hydrogen-bonded cholesteric liquid crystal polymer (CLCP) film with controlled porosity was fabricated as an optical sensor to distinguish between methanol and ethanol in alcohol solutions. To facilitate responding the alcohols, porosity was generated by removing the nonreactive liquid crystal agent, and the hydrogen bridges of CLCP were broken. The sensitivities of CLCPs to ethanol and methanol were obtained by monitoring the wavelength shifts of the transmission spectrum at different alcohol concentrations and ratios of methanol/ethanol. Changes in the central wavelength of the CLCP network transmission spectrum allowed the methanol–ethanol ratio to be discriminated. A linear relationship between wavelength shift of CLCP networks and alcohol concentration was obtained experimentally, and the sensor characteristics were explored. The sensitivities of the CLCPs were 1.35 and 0.18 nm/% to ethanol and methanol, respectively. The sensing sensitivity of cholesteric networks to alcohol molecules increased as the methanol–ethanol ratio declined. Therefore, CLCP could act as a stimuli-responsive material to distinguish the concentrations of acetone and ethanol in mixed solutions. Furthermore, the impact of UV intensity for curing a CLC mixture on the sensing sensitivity to the different alcohol concentrations was also studied. The higher UV intensity could enhance the sensitivity to alcohol molecules and distinguishing ability between methanol and ethanol.     

Effects of Hydrogen Bonding on the Transition Properties of Ethanol–Water Clusters: A TD-DFT Study

In this work, time-dependent density functional theory method was used to study the electronic transitions of hydrogen-bonded ethanol–water complexes Dimer-I, Dimer-II and Trimer. The intermolecular hydrogen bonds H₁···O₁ and O···H₂ were demonstrated by the optimized geometric structures of the three hydrogen-bonded ethanol–water complexes. It is demonstrated that the S₁-state electronic transitions for ethanol monomer and the hydrogen-bonded complex Dimer-I (through HB-I) should be of LE nature on the ethanol molecule, while those of complexes Dimer-II and Trimer should be of CT character from the hydrogen-bonded water molecule (through HB-II) to the ethanol moiety. The different electronic transition types should be the reasons for the tiny redshift of the S₁-state electronic energy for Dimer-I and the large blueshifts for Dimer-II and the Trimer compared with that of the ethanol monomer.     

Enhanced conversion of starch to cyclodextrins in ethanolic solutions by bacillus circulans var alkalophilus cyclomaltodextrin glucanotransferase

Improved formation of cyclodextrins (CDs) from starch in ethanolic solutions byBacillus circulans var alkalophilus cyclomaltodextrin glucanotransferase was studied. The β- and γ-CD yields increased and α-CD yield gradually decreased as the ethanol concentration was raised. The ethanol concentration required for maximal CD yield depended essentially on starch concentration. The ethanol's effect was pronounced at high starch concentrations. For example, with 30% (w/v) starch, the CD yield was 2.4-fold (146.5 g/L) in the presence of 15% (v/v) ethanol. The effect of dimethylsulfoxide on the formation of CDs was similar to that of ethanol. The disintegration of β- and γ-CDs were narrowly interdependent on the formation of a α-CD and malto-sugars. The amount of reducing sugars decreased from a dextrose equivalent value of roughly 7.5 to 4.5 in the presence of ethanol at starch concentrations 1-30% (w/v). The effect of ethanol on starchy materials from various sources was similar. It was concluded that ethanol retards the decomposition of β-CD by a general mechanism involving a decreased activity of water.