Preferential sorption versus preferential permeability in pervaporation

Transport of liquids by pervaporation takes place by a solution—diffusion mechanism. In order to investigate the “solution part” of this transport model, preferential sorption has been compared with preferential permeability. Sorption equilibria and pervaporation experiments for the systems water—ethanol—cellulose acetate, water—ethanol—polyacrylonitrile and water—ethanol—polysulfone have been investigated. Theoretical values of preferential sorption have been derived from Flory—Huggins thermodynamics, extended with concentration dependent interaction parameters. These calculated sorption values show a reasonable agreement with experimental values. The large difference in molar volumes between water and ethanol determines the preferential sorption of water in these systems to a great extent, and this effect increases with decreasing swelling value. Comparison of preferential sorption experiments with pervaporation experiments indicates that, apart from the effect of differences in diffusivity for the permeating components, preferential sorption contributes to a major extent to selective transport

Manure Matters, Volume 10, Number 7

Reducing Phosphorus Concentration of Ethanol Distiller Byproducts by Using Low Grain Phosphorus Corn Ethanol production plants are using about 800 million bu of corn each year to produce ethanol. In the ethanol production system, the starch is converted to ethanol and CO2 and the remaining grain material is called distiller byproduct (wet distiller grain plus soluble or dry distiller grain plus soluble). This byproduct is high in energy, protein, and P contents and is usually fed to feedlot cattle and other livestock. Removal of starch from grain concentrates P in the byproduct and when this high P material is added to ration, it increases P concentration of the ration and subsequently increases manure P concentration. Corn hybrids have different concentrations of P in grain. Results of a two-year field study conducted by the author in 1999 to 2000 indicated grain P concentration range of 0.21% to 0.33% among 12 commercial corn hybrids. Analysis of some other commercial hybrids in 2003 indicated that high P hybrids have P concentrations that can be more than double of those for low P hybrids. These low grain P hybrids can be used in rations to reduce its P content or can be used in ethanol production to reduce P content of the byproduct and hence make it a more environmentally friendly feedstuff. By reducing P concentration of the byproduct, the P concentration of manure will also reduce and that lessen the concern about soil P accumulation in the soil

Mesostructure of Mesoporous Silica/Anodic Alumina Hierarchical Membranes Tuned with Ethanol

Hierarchically structured membranes composed of mesoporous silica embedded inside the channels of anodic alumina (MS-AAM) were synthesized using the aspiration method. Ethanol is shown to have a significant effect on the type and organization of the mesoporous silica phase. Detailed textural analysis revealed that the pore size distribution of the mesoporous silica narrows and the degree of ordering increases with decreasing ethanol concentration used in the synthesis mixture. The silica mesopores were synthesized with pores as small as 6 nm in diameter, with the channel direction oriented in lamellar, circular, and columnar directions depending on the ethanol content. This study reveals ethanol concentration as a key factor behind the synthesis of an ordered mesoporous silica-anodic alumina membrane that can increase its functionality for membrane-based applications

A bouncing oil droplet in a stratified liquid and its sudden death

Droplets can self-propel when immersed in another liquid in which a concentration gradient is present. Here we report the experimental and numerical study of a self-propelling oil droplet in a vertically stratified ethanol/water mixture: At first, the droplet sinks slowly due to gravity, but then, before having reached its density matched position, jumps up suddenly. More remarkably, the droplet bounces repeatedly with an ever increasing jumping distance, until all of a sudden it stops after about 30 min. We identify the Marangoni stress at the droplet/liquid interface as responsible for the jumping: its strength grows exponentially because it pulls down ethanol-rich liquid, which in turn increases its strength even more. The jumping process can repeat because gravity restores the system. Finally, the sudden death of the jumping droplet is also explained. Our findings have demonstrated a type of prominent droplet bouncing inside a continuous medium with no wall or sharp interface.Comment: 6 pages, 4 figure

Microbubble Distillation Studies of a Binary Mixture

The characteristics of microbubble distillation of binary system of ethanol and water have been investigated. The study describes the use of a fluidic oscillator used to generate microbubbles. The effects of air temperature and liquid level on separation performance have been studied. The results demonstrate that ethanol concentration in the distilled phase decreases with the increasing liquid level. Increasing air temperature enhances the separation efficiency of the two components. It is shown that the ethanol fraction in distilled phase and the evaporation ratio increases by increasing the air temperature. Furthermore, the concentration of ethanol in the residual liquid shows a corresponding decrease. The vapour -liquid composition of microbubble distillation can exceed the isothermal equilibrium vapour-liquid composition by controlling the liquid level and the air temperature within the process

CaSO4 solubility in water–ethanol mixtures in the presence of sodium chloride at 25 °C. Application to a reverse osmosis process

Nowadays, the most common way to desalinate seawater is by reverse osmosis. As the degree of conversion during this process increases more freshwater is recovered from the feedwater. As a result, the salt concentration in the feed increases up to a point where the solubility limit could be reached. Experimentally, it is known that adding an organic substance such as ethanol to salty water induces salt precipitation. This work investigated the solid–liquid equilibrium of the system water–ethanol–NaCl–CaSO4 at 25 °C. Results show that as the ethanol content is increased CaSO4 solubility decreases. On the other hand, brine from the reverse osmosis plant at the University of Alicante was treated with ethanol to precipitate calcium sulfate and produce brine containing less calcium and sulfate. The treated brine was analyzed and its calcium content was compared with the predicted value based on the experimental data. The results suggest that it is possible to use ethanol to precipitate the salts from brine in order to obtain a higher degree of conversion in a reverse osmosis process. The obvious limitation of the method is the cost of recovering the ethanol by separation

Ethanol and Isopropyl Alcohol Exposure Increases Biofilm Formation in Staphylococcus aureus and Staphylococcus epidermidis

Introduction Alcohols, including ethanol and isopropyl alcohol, are used in clinical practice for disinfection and infection prevention. Recent studies, however, demonstrate that alcohols may enhance biofilm production in Staphylococci. Methods We quantified biofilm formation in the presence of ethanol and isopropyl alcohol in six different, well-characterized strains of Staphylococcus epidermidis and Staphylococcus aureus. After 24 h of biofilm development, each strain was exposed to normal saline (NS), ethanol, or isopropyl alcohol (40%, 60%, 80% and 95%) for additional 24 h incubation. Adherent biofilms were stained and optical density was determined. Viability of strains was also determined after alcohol exposure. Results Ethanol increased biofilm formation in all six strains compared to normal saline (p \u3c 0.05). There was increased biofilm formation with increasing ethanol concentration. Isopropyl alcohol also increased biofilm formation with increasing alcohol concentration in all six strains (p \u3c 0.01 vs NS). The slime-negative, chemical mutant strain of S. epidermidis increased biofilm formation after exposure to both alcohols, likely reverting back its primary phenotype through modulation of the intercellular adhesin repressor. All strains demonstrated viability after exposure to each alcohol concentration, though viability was decreased. Conclusion Ethanol and isopropyl alcohol exposure increases biofilm formation of S. aureus and S. epidermidis at concentrations used in clinical settings. Ethanol and isopropyl alcohol did not eradicate viable Staphylococci from formed biofilm

OPTIMIZATION OF PROCESS PARAMETERS IN ETHANOL PRODUCTION FROM CASSAVA WASTE SLURRY

The production of ethanol from renewable material is a sustainable avenue of ethanol production. This study focused on optimizing parameters affecting the production of ethanol generated from cassava waste slurry. The waste generated from cassava were characterized using proximate analysis. The proximate analysis results showed that the cassava waste slurry contain more moisture, volatile matter and fixed carbon. Central composite experimental design (CCD) was used to design and model the process with 50 experimental runs. CCD, with quadratic models explored the combined effect of five independent variables namely, temperature, PH, sugar concentration, time, and feed rate of the fermenting medium. The process parameters were optimized to obtain the optimal yield, purity and specific gravity. The experimental result showed that the maximum ethanol yield of 26% was obtained at a temperature of 400C, pH of 4, sugar concentration of 0.125, production time of 0.5hrs and feed value of 250ml. The statistical analysis of the yield, purity and specific gravity showed correlation coefficient (R2) of 0.88, 0.91 and 0.82 respectively. The effect of the process parameters showed that increase in the reaction temperature, feed, time, and pH increases the yield of ethanol while increase in the sugar concentration decreases the ethanol yield. The optimization result showed that the optimal yield of 10.54%, purity of 5.76% and specific gravity of 0.26 were obtained at reaction temperature of 30.06 ̊C, pH of 5.40, sugar concentration of 0.30ml/dm3 and reaction time of 1.03 hours

Collaborative permeation of drug and excipients in transdermal formulations. In vitro scrutiny for ethanol: limonene combinations

Enhancement of skin permeation of drugs is affected by the simultaneous co-permeation of excipients that hinder the predictivity of in vitro tests. The collaborative effects of two permeation enhancers (ethanol and d-limonene) of a lipophilic drug (alprazolam) have been simultaneously assessed in human skin under different in vitro conditions: integrated setups of diffusion cell experiments with selective concentration gradients of permeants (asymmetric) or without (symmetric) have been combined with coadministration dosages (all-in-one) at different concentrations or short-time skin pretreatment to scrutiny this mutual performance. Findings: Drug permeation is increased under moderated supersaturation but reaches a stationary level above 33 % of its solubility. Ethanol in absence of a concentration gradient increases ca.5 times basal drug permeation. Limonene until 20 % permeates human skin proportionally to its donor concentration but its effect does not depend on ethanol in symmetric conditions and is based on skin imbibition rather than on a carry-on effect. Simultaneous permeation of ethanol and limonene reaches a stationary state after 1.5 h, enough time to achieve maximal enhancement of alprazolam permeation. Additive enhancement is based on ethanol solubilisation maximized by skin saturation of terpene. Complementary analyses of skin disruption published in the literature are in line with these assessments and consolidate them