Ethanol-water Binary System Research Articles

Measurement and correlation of solubility and thermodynamic properties of dicumyl peroxide (DCP) in pure and binary solvents

The solid-liquid equilibrium data of dicumyl peroxide (DCP) in seven pure solvents and ethanol-water binary system and DMF-water binary system were measured from 274.15 K to 302.15 K by a gravimetric method under atmospheric pressure. The results show that the solid-liquid equilibrium solubility of DCP rapid increased with augmented temperature in different types of pure solvent while the solubility in binary solvent mixtures increases with the increasing of the fraction of ethanol and DMF. The measured data in pure solvents were correlated with several thermodynamic models including the modified Apelblat model, λh model and NRTL model. All the experimental results were agreement with the fitted values. Moreover, the NRTL model was adopted to calculate the enthalpy, entropy and Gibbs energy change during the dissolution process. And for the binary solvent system, the CNIBS/R-K model was used to correlate the solubility data. It was found that the correlated results by the NRTL model agreed best with the experimental data. Besides the results indicate that the mixing process of dicumyl peroxide in the experimental solvents was spontaneous and entropy-driven.

Exploring distillation-pervaporation hybrid process in a single column using hollow fiber pervaporation composite membranes as structured packing

This study developed a novel strategy for azeotrope separation such as ethanol-water binary system. Distillation-pervaporation hybrid process was employed by using hollow fiber pervaporation composite membranes as structured packing in a single hybrid column rather than using pervaporation as an externally connected unit of the distillation column. The separating limitation of azeotrope challenged in conventional distillation could be readily overcome by continually removing water from the hybrid system via pervaporation. The competition between distillation and pervaporation has been found to be cause of unexpected concentration distribution in the hybrid column. The mass flux of mixture decreased with time whereas the selectivity of water to ethanol first increased then decreased with time. Analysis of this system illustrated that the increase in heating power and membrane area shortened time for obtaining certain content of ethanol in the mixture. However, faster decline in mass flux occurred due to an increase in the removal rate of water. With respect to its simplicity, efficiency and broad applicability, this hybrid process is expected to provide a benchmark for the enhancement of distillation-pervaporation process by hollow fiber membrane packing.

Poly(vinyl alcohol)-Modified Membranes by Ti3C2T x for Ethanol Dehydration via Pervaporation.

In this paper, PVA/Ti3C2Tx mixed matrix membranes (MMMs) were prepared by mixing the synthesized Ti3C2Tx with the PVA matrix, and the pervaporation (PV) performance of the ethanol–water binary system was tested. The morphology, structural properties, and surface characteristics of the membranes were investigated by scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, degree of swelling, and water contact angle. The PVA/Ti3C2Tx MMMs exhibit excellent compatibility and swelling resistance. Moreover the effects of the Ti3C2Tx filling level, feed concentration, and operating temperature on the ethanol dehydration performance were systematically studied. The results demonstrated that the separation factor of PVA/Ti3C2Tx MMMs was significantly increased because of Ti3C2Tx promoting the cross-linking density of the membrane. Specifically, the membrane showed the best PV performance when Ti3C2Tx loading was 3.0 wt %, achieving a separation factor of 2585 and a suitable total flux of 0.074 kg/m2 h for separating 93 wt % ethanol solution at 37 °C.

Near-infrared spectroscopic study of molecular interaction in ethanol-water mixtures.

Given the importance of ethanol-water mixtures in many chemical and biological processes, the molecular interaction in ethanol-water binary system was studied using near-infrared (NIR) spectroscopy. Excess spectra (in form of excess absorption coefficient) and Gaussian fitting were applied to analyze low concentration ethanol-water mixtures, ranging from 0 to 10% (v/v). With the knowledge of aquaphotomics, six kinds of water species were identified for 0-10% ethanol-water system, and it was indicated that water can be a sensitive probe for analyzing the structural changes and the interactions in the solutions. The excess spectra and two-dimensional (2D) correlation spectroscopy were introduced for high concentration mixtures (10-100%) analysis and found that the intermolecular hydrogen bonding strength between ethanol and water reaches to the maximum at 40% ethanol concentration which may be related to some abnormal properties of alcoholic solutions reported previously. In 40-100% mixtures, ethanol molecules tend to initiate the self-association which leads to the weakening of the interaction between ethanol and water. This paper not only deepens the understanding of the structure and dynamics of alcoholic solution, but also opens a new perspective in molecular interaction analysis in aqueous system by understanding the roles of water.

Measurement and Correlation of Solubility and Thermodynamic Properties of Vinpocetine in Nine Pure Solvents and (Ethanol + Water) Binary Solvent

The solid–liquid equilibrium data of vinpocetine in nine pure solvents and ethanol–water binary system at temperatures ranging from 283.15 to 323.15 K was experimentally measured by gravimetric method under atmospheric pressure. For the different types of investigated solvent, the solid–liquid equilibrium solubility of vinpocetine increased with augmented temperature. Experimental solubility was fitted with several thermodynamic models including the modified Apelblat model, λh model, and nonrandom two-liquid (NRTL) model, as well as the combined nearly ideal binary solvent/Redlich–Kister model. All the fitted values were in satisfactory agreement with the experimental results. The thermodynamic parameters were calculated by the activity coefficients of vinpocetine in different solvents, which were obtained by NRTL model. The results demonstrated that the mixing process of vinpocetine with experimental solvents was spontaneous and entropy-driven.

Pressure swing distillation of azeotropic mixture – A simulation study

Summary The aim of this work is to simulate a pressure-swing distillation column for the separation and purification of ethanol from the ethanol–water binary system. The choice for this system is due to the importance of the ethanol–water separation. A steady-state equilibrium-stage model based on normalised MESH equations is used to simulate pressure-swing distillation column applied for the production of ethanol. All the work has been carried out using Aspen Plus simulator, version 13.2. Among the activity coefficient models available, the WILSON-RK model with binary parameters predicted by the Aspen Plus simulator is shown to be the most accurate to correlate the experimental vapor-/liquid equilibrium (VLE) data available for the ethanol–water system. The simulation has been satisfactorily carried out for a mixture of 20 mol% ethanol in water at 1 atm pressure and 90 °C with a molar flow rate of 100 kmol/h. The adjusting parameters include D/F ratio and reflux ratio of the two columns to get water purity of 99.5 mol% from the bottom of the Low Pressure Column (LPC) and the ethanol purity of 99.7 mol% from the bottom of High Pressure Column (HPC).

Gamma-radiolysis of the ethanol-water binary system in the presence of oxygen

A study of the gamma-radiolysis of the aerated ethanol-water system in a wide range of component concentrations has shown that the main process occurring in this system is selective radiation-induced oxidation of ethanol to acetaldehyde. The byproducts accumulating in the liquid phase are 2,3-butanediol and formaldehyde. The selectivity of the process increases with an increase in the alcohol content and decreases with an increase in the radiation dose. A theoretical radiolysis model created in this study is in good quantitative agreement with experimental data. Calculated product buildup curves exhibit breaking points characterized by an abrupt change in the radiation-chemical yield. Their origin is due to the complete burnout of oxygen in the closed system or its insufficiently rapid transfer to the liquid in the two-phase liquid/gas system.

Dissolution enhancement of curcumin via curcumin–prebiotic inulin nanoparticles

Dissolution enhancement of curcumin via prebiotic inulin designed to orally deliver poorly water-soluble curcumin at duodenum low acidity (pH 5.5) was investigated. Different prebiotic inulin–curcumin nanoparticles were synthesized in ethanol–water binary system at different pre-adjusted pH values. Characterization via FTIR, XRD and TGA revealed the formation of curcumin–inulin conjugates, whereas surface morphology via SEM and TEM techniques implied the formation of nanoparticle beads and nanoclusters. Prebiotic inulin–curcumin nanoparticles prepared at pH 7.0 demonstrated a maximum curcumin dissolution enhancement of ≈90% with respect to 30% for curcumin alone at pH 5.5. Power law constant values were in accordance with dissolution enhancement investigations. All samples show Fickian diffusion mechanism. XRD investigations confirm that inulin maintain its crystalline structure in curcumin–inulin conjugate structure, which confirms that it can exert successfully its prebiotic role in the gastrointestinal (GI) tract. Therefore, the use of curcumin–inulin nanoparticles can perform dual-mission in the GI tract at the duodenum environment; release of 90% of curcumin followed by prebiotic activity of inulin, which will probably play a significant role in cancer therapeutics for the coming generations.

Correlation of the Transport Properties for the Ethanol-Water System Using Neural Networks

Process design and simulation rely heavily on the accuracy and availability of transport property correlations. General models that combine the properties of pure components often lack the necessary accuracy. In this investigation, neural networks were used to model some important transport properties for the ethanol-water binary system. Specifically, a three-layer feed-forward neural network with six neurons in the hidden layer was used to model viscosity, thermal conductivity, surface tension and the Fick diffusion coefficient based on an array of experimental data. These neural network models were then compared to some conventional models that are commonly used to predict the aforementioned transport properties. The results showed that the neural network models were able to represent the experimental data very well for the system studied. One advantage in using neural network models to represent these properties is their ability to predict complex and interrelated behaviors without a priori information about the underlying model structure. Further, since all the models retain the same simple matrix structure, their integration into computer codes becomes straightforward and non-repetitive.

Saline extractive distillation process for ethanol purification

The aim of this work is to simulate and to optimize a saline extractive distillation process for purification of ethanol from the ethanol—water binary system. All the work was developed using ASPEN PLUS simulator, version 10.1-0, and the NRTL thermodynamic model developed for calculating activity coefficients of electrolytic systems, having as goal to get the anhydride ethanol (99.7 wt.%). In the development of this study, four saline agents were tested (NaCl, KCl, KI, CaCl 2). The complete process and a methodology to optimize it were established in the simulator in such a way all variables were optimized. It was verified that using only the saline extractive distillation process, it is possible to purify the ethanol from the fermentation broth composition obtaining a product with high purity. Finally, a comparative study using electrolyte distillation process and the integrated distillation process (simple and extractive distillation) was carried out.