Evaluation of the performance of heat pump-assisted distillation of an ethanol–water mixture

The process of separation of an ethanol–water mixture was simulated. A heat pump system was then implemented on the distillation column with the highest energy requirements in the process. Complete elimination of hot and cold utilities of the pretreatment column was obtained through an improved system by application of a heat pump at a compressor work of 406.6 kW. Installation of the heat pump system on the pretreatment column of the system results in a reduction of 10.7% of annual operating costs and 6.6% of the total annual costs (TAC). However, the capital costs of the process will enhance by 22.6%.     

Application of microwave heating to pervaporation: A case study for separation of ethanol–water mixtures

Membrane pervaporation experiments for dewatering of water–ethanol mixtures were conducted, using a polymeric hydrophilic membrane, under microwave and conventional heating in a multimode microwave oven and a convection oven, respectively. Three feed temperatures (33.5, 45.5 and 51.5 °C) and two feed compositions (5.5 wt% and 20 wt% water in the feed) were considered. At 20 wt% water content, higher water fluxes through the membrane were obtained in the convection oven. At lower water content in the feed (5.5 wt%), the opposite effect was observed; the water fluxes were higher under microwave heating over the considered temperature range. These differences may arise from the different dielectric properties and consequently thermal behaviour of the feed mixtures under microwave heating. Microwave coupling with ethanol is stronger than with water. Moreover, unlike water, the dielectric loss factor of ethanol increases with temperature, which makes microwave dissipation preponderant in hot areas. Hence, high ethanol concentrations in the feed can easily induce thermal gradients.     

Membrane distillation and pervaporation for ethanol removal: are we comparing in the right way?

A new glance on the comparison between membrane distillation (MD) and pervaporation is performed. There is a difficulty in this comparison, mainly due to different hydrodynamic conditions reported in the literature. Pervaporation and MD are similar although the comparison between these two processes can be tricky. In that way, how can we make a proper comparison between results of these two processes? This study proposes a reasonable comparison between MD and pervaporation for ethanol–water separation. Two very distinct regions of results in terms of selectivity and flux are presented. Feed temperature and composition and concentration polarization effects were also investigated.     

Physiochemical insight into the solution behavior of cationic gemini surfactant in water and ethanol–water systems

Surfactants in water and both alcohol-water mixed solutions are used extensively in a host of industrial applications. This work presents the solution behavior and micellar transition of a cationic gemini surfactant (GS): N,N′-dihexadecyl-N,N,N′,N′-tetramethyl-N,N′-ethanediyl-diammonium dibromide (16-2-16) in water and mixed water-ethanol media. Phase behavior for 16-2-16 in the ethanol–water system was investigated at ambient temperature. The rheological data obtained for these systems at varying alcohol concentrations showed that the system viscosity (η) decreased with as the ethanol concentration increased. Small-angle neutron scattering (SANS) was used to probe the structural details of the cationic micelles as a function of ethanol concentration and temperature. The scattering data inferred a structural transition from unilamellar vesicles (ULV) through rod-like micelles to ellipsoidal micelles occurs that is dependent on the solvent composition and temperature indicating the behavior of ethanol molecules as a cosolvent in the process of micelle breaking. The plausible physicochemical interactions in the 16-2-16-ethanol mixed system were further investigated using a computational simulation study employing density functional theory (DFT)/B3LYP (Gauss View 5.0.9) utilizing a 3-21G basis set.     

Liquid–liquid interface induced PDMS-PTFE composite membrane for ethanol perm-selective pervaporation

Pervaporation has great potential in the separation of many significant mixtures. However, excessive penetration of separation layer into the substrate pores enhances the transport resistance of solvent molecules, which impedes the development of pervaporation membrane. In this study, a facile floating-on-water (FOW) method was used to prepare poly(dimethylsiloxane) (PDMS)/polytetrafluoroethylene (PTFE) composite membranes. The formation of separation layer and preparation of composite membrane were step-by-step completed through this liquid–liquid interface induced method. The PDMS layer thickness could be precisely regulated from 0.5 to 8 μm. Moreover, the pore penetration could be controlled by optimizing pre-crosslinking density, crosslinking time on water and polymer solution volume. The obtained PDMS/PTFE composite membrane exhibited a high flux of 2016 g·m⁻²·h⁻¹ with the separation factor of 12 when separating ethanol from a 5 wt% ethanol/water mixture. The performance of the membrane could be stable for over 200 h, exhibiting great potential in ethanol perm-selective pervaporation.     

Phase mixture modeling of the grain size dependence of Young’s modulus and thermal conductivity of alumina and zirconia ceramics

The grain size dependence of Young’s modulus and thermal conductivity of alumina and zirconia ceramics is predicted via phase mixture modeling, using both analytical and numerical approaches. Using typical values for the thickness and properties of the grain boundaries, the equivalent volume fraction of “grain boundary phase” is calculated for a given grain shape. Based on this volume fraction estimate and a rough estimate of the grain boundary properties, the effective properties of the polycrystalline materials are calculated and compared in terms of volume-equivalent sphere diameters. For grains of cubic and tetrakaidecahedral shape excellent agreement is found between numerical calculations and analytical predictions based on the lower Hashin-Shtrikman bound. The grain size dependence is extremely weak for Young’s modulus, but can be more significant for thermal conductivity, especially when the intrinsic conductivity of the material is high. The predictions are compared to literature data.     

Exclusive and fast water channels in zwitterionic graphene oxide membrane for efficient water–ethanol separation

Graphene oxide (GO) membranes have shown great prospects as the next-generation membranes to tackle many challenging separation issues. However, the employment of GO membranes remains difficult for the precise separation of molecules with strong coupling effect and small size discrepancy such as water–ethanol. Herein, a new strategy of constructing exclusive and fast water channels in GO membrane was proposed to achieve high-performance water–ethanol separation via the synergy between zwitterion-functionalized GO and hydrophilic polyelectrolyte. The as-formed ordered and stable channels possess high-density ionic hydrophilic groups, which benefit from inhibiting the strong coupling between water and ethanol, facilitating the fast permeation of water molecules while suppressing ethanol molecules. As a result, the ultrathin GO-based membrane acquires exceptionally high separation performance with a flux of 3.23 kg/m² h and water–ethanol separation factor of 2,248 when separating water–ethanol (10 wt%/90 wt%) mixture at 343 K. This work paves a feasible way to construct 2D channels for the high-efficiency separation of strong-coupling mixtures.     

hERG Optimization of Benzofuro−Pyridine and Pyrazino−Indole Derivatives as MCHR1 Antagonists

Obesity is a global epidemic associated with multiple severe diseases. Several pharmacotherapies have been investigated including the antagonists of melanin concentrating hormone receptor 1 (MCHR1). The design, synthesis, and biological studies of novel MCHR1 antagonists based on benzofuro−pyridine and pyrazino−indole scaffold was performed. We confirmed that fine-tuning lipophilicity and basic pK_a by modifying the benzyl group and introducing different substituents on the aliphatic nitrogen sidechain decreases both hERG inhibition and metabolic clearance. We have succeeded to develop excellent in vitro parameters in the case of compounds 17 (4-[(5-chloropyridin-2-yl)methoxy]-1-[4-(2-hydroxyethyl)-8-oxa-4-azatricyclo[7.4.0.0²,⁷]trideca-1(13),2(7),9,11-tetraen-11-yl]-1,2-dihydropyridin-2-one monohydrochloride) and 23 g (4-[(5-chloropyridin-2-yl)methoxy]-1-(1,2,3,4-tetrahydropyrazino[1,2-a]indol-8-yl)pyridin-2(1H)-one monohydrochloride), which can be considered as valuable tools for further pharmacological investigation.     

Development of novel grafted hybrid PVA membranes using glycidyltrimethylammonium chloride for pervaporation separation of water–isopropanol mixtures

Tetraethylorthosilicate incorporated hybrid poly(vinyl alcohol) membranes were grafted with glycidyltrimethylammonium chloride (GTMAC) in different mass%. The resulting membranes were subjected to physico-chemical investigations using Fourier transform infrared (FTIR) spectroscopy, wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA) and scanning electron microscopy (SEM). The effects of grafting and feed composition on pervaporation performance of the membranes were systematically investigated. The membrane containing 30 mass% of GTMAC exhibited the highest separation selectivity of 1570 with a flux of 1.92 × 10^?2 kg/m² h at 30 °C for 10 mass% of water in the feed. The total flux and flux of water are almost overlapping each other, manifesting that these membranes could be used effectively to break the azeotropic point of water–isopropanol mixtures. From the temperature dependent diffusion and permeation values, the Arrhenius activation parameters were estimated. The activation energy values obtained for water permeation (E_pw) are two to three times lower than those of isopropanol permeation (E_pIPA), suggesting that the developed membranes have higher separation ability for water–isopropanol system. The E_p and E_D values ranged between 63.73 and 33.07, and 62.78 and 32.75 kJ/mol, respectively. The positive heat of sorption (ΔH_s) values was obtained for all the membranes, suggesting that Henry's mode of sorption is predominant in the process.     

Separation of water–isotopes mixture in continuous-flow thermal diffusion columns for recovery of deuterium

The present study deals with the estimation of deuterium recovery from the separation of water–isotopes mixture (H₂O–HDO–D₂O) by continuous-flow thermal diffusion. First, the equations for predicting the degrees of separation for each component in H₂O–HDO–D₂O system were derived by following the same procedure performed in the previous work. The recovery of deuterium (D) was then estimated from the degrees of separation of HDO and D₂O and confirmed with the experimental results.     

Optimization of platinum dispersion in Pt–PEM electrodes: application to the electrooxidation of ethanol

Nafion® can be used as a solid polymer electrolyte in a PEM fuel cell. Direct platinization of the membrane was realized by chemical reduction of a platinum compound. The platinization procedure was modified to enhance the roughness factor and thus to improve the electrocatalytic activity towards ethanol electrooxidation. The Pt–PEM electrodes were characterized by TEM, atomic absorption analysis, cyclic voltammetry and their polarization curves for ethanol electrooxidation.     

Optimization of platinum dispersion in Pt–PEM electrodes: application to the electrooxidation of ethanol

Nafion® can be used as a solid polymer electrolyte in a PEM fuel cell. Direct platinization of the membrane was realized by chemical reduction of a platinum compound. The platinization procedure was modified to enhance the roughness factor and thus to improve the electrocatalytic activity towards ethanol electrooxidation. The Pt–PEM electrodes were characterized by TEM, atomic absorption analysis, cyclic voltammetry and their polarization curves for ethanol electrooxidation.     

Strategy for improving the capacity and rate performance of LiNixCoyMn1−x−y electrode using Ti3C2Tx MXene additives

With the expanding range of applications for lithium-ion batteries, a great deal of research is being conducted to improve their capacity, stability, and charge/discharge rates. This study was performed to investigate the effects of MXene, which has a large surface area and metallic conductivity, as a conductive additive to the cathode, on electrochemical performance. The two-dimensional material MXene constructs a conductive network with zero-dimensional carbon black in plane-to-point mode to improve conductivity and contact area with active materials, thereby facilitating fast charge transfer. The conductive network reduces the internal resistance and polarization of the cathode and aids the diffusion of electrons. The electrode containing an appropriate amount of MXene showed improved rate performance, high discharge capacity (123.9 mAh g⁻¹ at 4 C), and excellent cycle stability at a high scan rate (125.8 mAh g⁻¹ at 2 C after 150 cycles) compared to pristine electrodes. Based on these results, Ti₃C₂T_x MXene is a promising conductive additive in the battery field.     

New water‐tolerant supported molten indium catalyst for the selective catalytic reduction of nitric oxide by ethanol

The catalytic activity and selectivity of indium supported on controlled pore glass (In‐CPG‐SMMC) were investigated and compared with those of H‐ZSM‐5 and In/γ‐Al₂O₃ for the selective catalytic reduction of nitric oxide by ethanol under net oxidizing conditions, in the absence and presence of water vapors. Even though the support of In‐CPG‐SMMC is almost pure silica (94–99% SiO₂, 1–6% B₂O₃, 0.05–0.3% Na₂O), the activity of this catalyst was found to be comparable with that of the conventional catalysts. The presence of steam in the feed enhanced catalyst activity over the entire temperature range studied. At temperatures above 500°C the ability of H‐ZSM‐5 and In/γ‐Al₂O₃ to reduce NO to N₂ was surpassed by the supported indium catalyst. This revised version was published online in July 2006 with corrections to the Cover Date.     

Optimization and statistical modeling of catalytic oxidation of 2-propanol over CuMnmCo2−mO4 nano spinels by unreplicated split design methodology

Optimization of 2-propanol oxidation over CuMn_mCo_2?mO₄ nanospinels was carried out by a split design method. 15-term model was proposed to fit the experimental data. The model revealed that both whole plot and subplot variables have significant effects on conversion of 2-propanol. The model predicted the interaction of subplot and whole plot variables as well as their importance. The maximum conversion of 2-propanol was observed over CuMn₂O₄ (x₁ = 0.33, x₂ = 0, x₃ = 0.67) at calcination and reaction temperatures of 800 °C (z₁ = 1) and 300 °C (z₂ = 1), respectively. The predicted response and the response obtained from experiment for optimum conditions were 93.36 and 96, respectively.     

The anodic behaviour of iron in ethanol—water solutions in the presence and absence of NaClO4 as the supporting electrolyte

The anodic behaviour of iron in ethanol—water solutions and the effect of NaClO₄ have been investigated on the basis of potentiostatic polarization curves and electrochemical impedance plots. The influence of the water content in ethanol (6–80 vol.%) on the anodic polarization curves without a supporting electrolyte is to increase the anodic current density monotonically with potential. Furthermore, for a given potential, the current density is higher when the water content is increased. In the presence of NaClO₄ the polarization curves shift towards more high current in the low anodic potential range. Thus, addition of NaClO₄ not only increases the conductivity of ethanol solutions in its role as a supporting electrolyte, but it also modifies the electrochemical process significantly.     

Mixed matrix membranes of Matrimid 5218 loaded with zeolite 4A for pervaporation separation of water–isopropanol mixtures

Mixed matrix membranes were prepared by incorporating zeolite 4A into polyimide of Matrimid 5218 using solution-casting technique. The fabricated membranes were characterized by scanning electron microscopy (SEM), differential scanning calorimeter (DSC) and thermo gravimetric analysis (TGA). It was found that the higher annealing temperature of 250 °C is more favorable to improve adhesion between zeolite and polymer phases. Effects of different parameters such as temperature (30–60 °C), water content in feed (10–40 wt.%), zeolite loading (0–15 wt.%) and polymer content (10 and 15 wt.%) on pervaporation dehydration of isopropanol were studied. Sorption studies were carried out to evaluate degree of swelling of the membranes in feed mixtures of water and isopropanol. The experimental results showed that both pervaporation flux and selectivity increase simultaneously with increasing the zeolite content in the membranes. The membrane containing Matrimid 5218 (10 wt.%)–zeolite 4A (15 wt.%) exhibits the highest separation factor (α) of 29,991 with a substantial permeation flux (J) of 0.021 kg/m² h at 30 °C for 10 wt.% of water in the feed. The PV performance was also studied in term of pervaporation separation index (PSI). Permeation flux was found to follow the Arrhenius trend over the investigated temperature range.     

Separation of isopropyl alcohol–water mixtures by pervaporation using copolymer membrane: Analysis of sorption and permeation

Membrane made from copolymer of acrylonitrile and methyl acrylate designated as PANMA was used for pervaporative dehydration of isopropyl alcohol (IPA) over the concentration range of 75–100 wt% IPA in water. Sorption of the membrane was evaluated in terms of thermodynamic interaction parameters based on Flory–Huggins lattice model. Engaged species induced clustering (ENSIC) model was also used to explain swelling of the membranes. Coupling in sorption was explained by activity coefficient of water and IPA in feed and membrane using Flory–Hugging thermodynamics and also by interpolating ENSIC parameters. Intrinsic membrane properties like partial permeability and membrane selectivity was also determined. Total solvent volume fraction (TSVF) model was used to determine diffusion coefficient and plasticization coefficient of the solvents. The membrane was found to show very high water selectivity (3540) and good flux (3.3 kg/m² h μm) for highly concentrated (99.8 wt%) IPA at 30 °C temperature.