Ethanol-water System Research Articles

Tunable size and shape of conductive poly(N‐methylaniline) based on surfactant template and doping

AbstractPoly(N‐methylaniline) (PNMA) is one of the polyaniline derivatives with N‐substituted position. Polyaniline derivatives have attracted attention due to their higher solubility in common solvents than pristine polyaniline, but they still possess lower electrical conductivity. In this work, PNMA was synthesized via chemical oxidative polymerization in an ethanol–water system. The effect of surfactant type, namely anionic sodium dodecylbenzenesulfonate (SDBS), cationic cetyltrimethylammonium bromide and non‐ionic Tween20, on the electrical conductivity, doping level and morphology was investigated. PNMA prepared with the SDBS system possessed the highest electrical conductivity among the obtained PNMAs with and without surfactants. The effect of /NNMA dopant mole ratios on the re‐doping, crystallinity, morphology and particle size was also examined. Using an /NNMA mole ratio of 10:1 in the re‐doping process provided the highest electrical conductivity of 15.53 ± 2.5 S cm−1, a doping level of 55.59%, along with hollow spherical particles with the thinnest membrane. Electron microscopy images revealed that the morphology of PNMA particles depended mainly on the surfactant type but not the /NNMA mole ratio. © 2019 Society of Chemical Industry

Spontaneous ethanol–water emulsification as a precursor for porous particle formation: Understanding the role of dissolved carbohydrates

Quiescent mixing of aqueous lactose solution with ethanol by gentle pouring allowed controlled observation of a transient, spontaneous emulsification process between ethanol and water. This phenomenon contrasts with the conventional stable phase-separation process for ethanol–water systems with other solutes. The presence of lactose in the dissolved state was deduced to be the key factor causing spontaneous emulsification. This explains the transitional behavior of the phenomenon. Further experiments with aqueous maltodextrin solution, using the same experimental technique, confirmed this phenomenon. The mechanisms determined in this work will form the basis of porous-particle synthesis via the antisolvent vapor-precipitation technique.

Dynamic High-Pressure Microfluidization-Treated Pectin under Different Ethanol Concentrations.

We previously reported that dynamic high-pressure microfluidization (DHPM) can degrade pectin in aqueous solution. In this study, we further investigated the effect of DHPM on pectin in water-ethanol systems. In the absence of DHPM treatment, it was found that pectin exhibited increased average particle size and unchanged average molecular weight, but a decline in reducing-sugar-ends content with the increase of ethanol concentrations (0–10% v/v). These results indicated that the addition of ethanol induced aggregation of pectin. During DHPM treatment, pectin underwent disaggregation and degradation under all measured ethanol concentrations. Disaggregation was enhanced but degradation was weakened with the increase of ethanol concentration. FT-IR and UV spectra indicated that demethylation but no β-elimination occurred in the water-ethanol system during DHPM. Finally, the mechanism of DHPM-induced disaggregation and degradation of pectin under a water-ethanol system was updated. This work may help us to find a suitable condition for reducing the degradation of pectin during the process of homogenization.

Recent Advances in Three-Component Cyclocondensation of Dimedone with Aldehydes and Malononitrile for Construction of Tetrahydrobenzo[b]pyrans Using Organocatalysts

Background: The majority of naturally occurring compounds, pharmaceuticals, and drug-candidate molecules possess heterocyclic scaffolds. In this context, tetrahydobenzo[b]pyrans are of considerable importance. In the line with the synthesis of these valuable heterocyclic compounds, the researchers tried to synthesize these molecules using different organocatalysts. The development of new strategies for three-component condensation of dimedone, various aldehydes and malononitrile for construction of tetrahydrobenzo[b]pyrans is of particular interest to organic chemists and pharmacologists. Objective: In this review, three-component catalyzed synthesis of tetrahydrobenzo[b]pyran compounds is introduced, focusing on the developments in the use of organocatalysts. Organocatalytic approaches were investigated for the synthesis of tetrahydrobenzo[b]pyrans. This contribution covers the literature concerning the synthesis of heterocycles referred to, in recent times. Conclusion: This review article is associated with the study of the three-component synthesis of tetrahydrobenzo[b]pyrans using organocatalysts. This review also provides an insight into the importance of these heterocycles. In the vast majority of these reactions, water and water-ethanol system have been used as green solvent media for implementation of them. The use of green solvents, the development of less toxic and promising reagents/catalysts as well as the design of inexpensive and reliable approaches are some of the principles of green chemistry, and most of the methods are benefited from them. Tetrahydrobenzo[b]pyrans and organocatalysts open avenue ofnew horizons. The recyclability of the many of these organocatalysts offers an additional merit for the use of these catalysts in 3-CR of aldehydes, dimedone, and malononitrile reactions.

Synthesis of one-dimensional calcium silicate nanowires as effective broadband optical limiters.

Synthesis of inorganic nanostructures with novel morphologies has attracted increasing attention from chemistry and materials science researchers. Calcium silicate nanowires (CaSiO3 NWs) were successfully prepared using a water-ethanol mixture solution system via hydrothermal synthesis. The resulting CaSiO3 NWs were uniform, with widths averaging 10-20nm and lengths up to several micrometers. The synthesized silicate NWs were highly crystalline and mainly constituted of SiO4 tetrahedra. The nanosecond optical limiting (OL) effects were characterized using an open-aperture (OA) Z-scan technique with 4ns laser pulses at 532 and 1064nm. These CaSiO3 NWs exhibited excellent OL performance, superior to that of carbon nanotubes, which are a benchmark optical limiter. Input-fluence-dependent scattering measurements suggested that nonlinear scattering played an important role in the observed OL behavior in the CaSiO3 NWs at 532 and 1064nm. This study provides new insights into the silicate nanowires, which will help in the design and preparation of 1D materials with improved nonlinear optical properties.

Experimental Investigation and Design of Rotating Packed Beds for Distillation

Improved separation efficiency and flexibility are of major importance in the downstream processing of liquid mixtures in the chemical industry, in order to respond to fluctuating demand and raw material quality. The application of the high gravity (HiGee) concept in Rotating Packed Beds (RPBs) has the potential to meet these requirements for the separation of liquid mixtures. The current work provides an analysis of the potential improvements gained by RPBs. The flexibility of RPBs is analyzed based on an experimental investigation, which evaluates the effect of rotational speed, different rotor configurations and F-factors on separation efficiency. Batch distillation experiments were performed in a single-stage pilot plant RPB with the ethanol-water system under total reflux conditions at atmospheric pressure. An analysis of the number of transfer units (NTU) reveals that separation efficiency in RPBs is not necessarily proportional to the rotational speed. There is rather an optimal rotational speed for each investigated rotor configuration. A maximum of 3.7 transfer units was achieved for a rotor with outer packing diameter of 0.36 m and an axial height of 0.01 m. Special emphasize in this experimental study is placed on the analysis of the contributions to mass transfer from the packing and the casing, which can contribute significantly to the overall mass transfer in RPBs.

Formation of aluminum diphosphonate mesostructures: The effect of aluminum source

Mesostructured aluminum phosphonates (AOP-x) bridging with 1,1′-hydroxyl ethylidene groups, including a lamellar mesostructure (AOP-N) with crystalline framework, a well-ordered 2D-hexagonal mesophase (AOP-Cl), and a particle-packed mesostructure (AOP-S), were simply synthesized in the presence of surfactant cetyltrimethylammonium bromide in the ethanol-water system, by choosing Al(NO3)3, AlCl3 and Al2(SO4)3 as the aluminum source, respectively. The crystallinity, morphology, mesophase, and skeletal structure of the as-prepared materials were characterized by XRD, TEM, SEM, 27Al, 31P and 13C MAS NMR, and nitrogen sorption techniques. After calcination under N2 at 350 °C, the calcined AOP-x samples consist of aluminum phosphonate and phosphate, possessing desirable specific surface areas of 116–585 m2/g. The effect of the inorganic counteranions (NO3−, Cl− and SO42−) from the aluminum source on the formation of different AOP-x mesostructures was discussed in terms of their bind strength to the headgroups of the surfactant micelles, suggesting the potential for designed synthesis of non-silica-based mesostructured organic-inorganic hybrid materials.

A novel dual-nano assisted synthesis of symmetrical disulfides from aryl/alkyl halides

Here, we have reported a novel approach towards dual-nano assisted synthesis of disulfides from coupling of alkyl/aryl halides and sulfur nanoparticles. The indium oxide nanoparticles as catalyst expedite the conversion and sulfur nanoparticle notably enhances the miscibility, providing a faster, high yielding and cost-effective process in ethanol-water system. The method has synthetic advantages in terms of mild reaction framework, catalyst regeneration, and absence of any sulfide or polysulfide linkage as by-product leading to a column free synthesis. A variety of alkyl, aryl and heteroaryl symmetrical disulfides are obtained in good to excellent yields up to exceeding 98%.

Protective Bleaching of Camel Hair in a Neutral Ethanol⁻Water System.

As conventional bleaching under alkaline conditions is chemically damaging to protein fibers, a three-stage protective bleaching process in neutral ethanol–water mixtures was proposed for camel hair using mordanting with ferrous salts, oxidative bleaching with hydrogen peroxide, and reductive bleaching with sodium hydrosulfite. The aim of this work was to improve the whiteness degree of camel hair without substantial tenacity loss. In addition, the roles of ethanol during the bleaching treatment were also examined by characterizing the fibers using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction. The whiteness degree and mechanical properties of camel hair bleached in the neutral ethanol–water system were significantly superior to those of fibers bleached by a conventional method. SEM images showed no visible cracks on the scales of fibers bleached in the ethanol–water system, whereas large grooves were observed on fibers bleached in aqueous solution. TEM images confirmed the positive influence of ethanol on the mordanting process, and FTIR spectra suggested that ethanol reduced the breakage of hydrogen bonds in the fibers during the oxidative bleaching process. These findings indicate the potential of this protective bleaching method for application to a broad range of other natural protein fibers.

Association of hydrophilic derivatives of chlorophyll a in ethanol–water and ethanol–water–solubilizer systems

Electronic absorption spectroscopy and fluorescence spectroscopy were used to study conditions for the formation of associates of amphiphilic phorbins and chlorins in an ethanol–water system. The conditions and degree of disaggregation in the presence of solubilizing additives of nonionic surfactants (Tween 80) and biocompatible polymers (polyethylene glycol and polyvinylpyrrolidone) were also investigated. The propensity of the macroheterocycles based on chlorophyll a to association in water-alcoholic solutions decreases on going from covalently bound dimeric structures to monomeric ones, on going from phorbins to chlorins and on accumulating hydrophilic glycol or positively charged alkylammonium fragments in the molecule. Among the considered solubilizers, the nonionic surfactant Tween 80 emerged as the most efficient means for destroying chlorin associates in water–alcohol solutions with a high content of water.

Fluorescence emission from hyperbranched polycarbonate without conventional chromohpores

Fluorescent polymers without non-conventional luminescent units have attracted great attention due to their excellent biocompatible. In this paper, we fabricated a kind of nonconjugated hyperbranched polycarbonate (HBPC) through one-pot transesterification method using diethyl carbonate and trimethylolpropane under solvent and catalyst-free condition. Unexpectedly, the HBPC can exhibit bright blue photoluminescence without any treatment under a 365 nm UV light. The results show that the fluorescence of HBPC in ethanol displays the excitation- and concentration-dependent behaviors. In addition, its fluorescence exhibits an aggregation-enhanced emission (AEE) effect in water-ethanol system. The fluorescence emission behaviors of HBPC can be well rationalized by the clustering-induced emission (CIE) mechanism. In other words, the fluorescence is caused by the electron cloud overlap within the clustering of carbonate groups. The TEM images further reveal that the rigidity conformation of HBPC was formed in the higher concentration because of the existence of hydrogen bonds. Besides, the ball and stick model firstly simulates the HBPC emission behavior.

The insight study of SnO pico size particles in an ethanol-water system followed by its biosensing application

Pico sized Stannous oxide particles (SnO PPs) were synthesized in an ethanol-water solvent system on the surface of nitrogen doped graphene oxide (GO). The highly conductive support was a combination of dual interactions between 4-aminomethylbenzylamine (AMBA) and GO. The oppositely positioned –NH2 linkers of the AMBA were covalently incorporated into the GO matrix through condensation reaction followed by the strong π – π stacking interactions between aromatic rings of AMBA and GO. The change in the local chemical environment of GO via dual interactions provided a suitable atmosphere for the growth and dispersion of SnO PPs on GO-AMBA surface. The possible mechanism for the formation of SnO in an ethanol-water solvent system was evaluated. Furthermore, a light was shed on the factors responsible for the pico size of SnO particles synthesis along with its phenomenal distribution on the GO-AMBA surface. The catalyst containing SnO PPs was deployed as a biosensor for the detection of ascorbic acid (AA) for the very first time. A very wide linear range of 5.0 × 10−5–7.0 × 10−3 M, limit of detection (LOD) of 1.19 × 10−5 M along with excellent practical feasibility, storage stability, repeatability and selectivity towards AA electrooxidation showed the excellent synergy between nitrogen-rich GO surface and SnO PPs. The sensitivity (885.54 µAmM−1cm−2) of the catalyst was the most attractive feature, as it was obtained in the presence of 5 and 2-fold higher concentration of UA and DA interfering species respectively.

Concentration Dependences of the Surface Tension and Density of Solutions of Acetone–Ethanol–Water Systems at 293 K

Concentration dependences of the surface tension and density of solutions of three-component acetone–ethanol–water systems and the bounding binary systems at 273 K are studied. The molar volume, adsorption, and composition of surface layers are calculated. Experimental data and calculations show that three-component solutions are close to ideal ones. The surface tensions of these solutions are calculated using semi-empirical and theoretical equations. Theoretical equations qualitatively convey the concentration dependence of surface tension. A semi-empirical method based on the Kohler equation allows us to predict the concentration dependence of surface tension within the experimental error.

Rationale Design, Synthesis, Cytotoxicity Evaluation, and Molecular Docking Studies of 1,3,4-oxadiazole Analogues.

1,3,4-Oxadiazole heterocycles possess a broad spectrum of biological activities. They were reported as potent cytotoxic agents and tubulin inhibitors; hence it is of great interest to explore new oxadiazoles as cytotoxic agents targeting tubulin polymerization. Two new series of oxadiazoles (5a-h and 12a-h) were synthesized, structurally related to the heterocyclic linked aryl core of IMC-038525, NSC 776715, and NSC 776716, with further modification by incorporating methylene linker. The 2,5-disubstituted-1,3,4-oxadiazoles (5a-h and 12a-h) were synthesized by refluxing an equimolar mixture of the intermediates [(4) and (8a-d)] and aromatic aldehydes in water-ethanol system using sodium bisulphite catalyst. The cytotoxicity evaluation was carried out according to the National Cancer Institute (NCI US) Protocol, while the tubulin polymerization assay kits from Cytoskeleton ™(bk011p) was used to perform an in vitro tubulin polymerization assay. 2-(5-{[(4-Chlorophenyl)amino]methyl}-1,3,4-oxadiazol-2-yl)phenol (5f) and 2-[(2,4-dichlorophenoxy) methyl]-5-(3,4-dimethoxyphenyl)-1,3,4-oxadiazole (12c) showed maximum cytotoxicity with the mean percent growth inhibitions (GIs) of 71.56 and 72.68 respectively at 10 µM drug concentrations. Both the compounds (5f and 12c) showed superior cytotoxicity than clinically prevalent anticancer drugs, Imatinib and Gefitinib in one dose assay. The compound 12c showed promising results in five dose assay, with GI50 values varies between 1.61 and >100 µM. Furthermore, the compounds, 5f and 12c also inhibited the polymerization of tubulin with, an IC50 of 2.8 and 2.2 µM, respectively. The oxadiazoles reported herein are tubulin inhibitors and cytotoxic agents. These findings will be helpful in future drug design of more potent tubulin inhibitor cytotoxic agents.

Solid–liquid phase equilibrium and mixing thermodynamic analysis of coumarin in binary solvent mixtures

ABSTRACTThe solubility of coumarin in three aqueous solvent mixtures (methanol + water, ethanol + water and acetone + water) was experimentally determined by a gravimetric method at atmospheric pressure. The experimental solubility data were fitted using the modified Apelblat equation, non-random two-liquid (NRTL) equation, the combined nearly ideal binary solvent/Redlich–Kister equation and the Jouyban−Acree equation, respectively. All the equations were proven to be able to correlate the experimental data, and the modified Apelblat equation could obtain better correlation results than the other three models. The solubility of coumarin increases with increase in temperature. At the same temperature, the solubility increases with increase in mole fraction of organic solvents except for the ethanol–water system which shows a unimodal curve. In addition, the apparent thermodynamic properties of the mixing process were calculated based on the NRTL model and the experimental solubility data.

Comparison of the Binding Geometry of Free-Base and Hexacoordinated Cationic Porphyrins to A- and B-Form DNA.

Although the transition from B-DNA to the A-form is essential for many biological concerns, the properties of this transition have not been resolved. The B to A equilibrium can be analyzed conveniently because of the significant changes in circular dichroism (CD) and absorption spectrum. CD and linear dichroism (LD) methods were used to examine the binding of water-soluble meso-tetrakis(N-methylpyridinium-4-yl)porphyrin (TMPyP) and its derivatives, Co-TMPyP, with B- and A-calf thymus DNA. B- to A-transitions occurred when the physiological buffer was replaced with a water-ethanol mixture (∼80 v/v %), and the fluorescence emission spectra of TMPyP bound to DNA showed a different pattern under ethanol–water conditions and water alone. The featureless broad emission bands of TMPyP were split into two peaks near at 658 and 715 nm in the presence of DNA under an aqueous solution. In the case of an ethanol–water system, however, the emission bands are split in two peaks near at 648 and 708 nm and 656 and 715 nm with and without DNA, respectively. This may be due to a change in the solution polarity. On the basis of the CD and LD data, TMPyP interacts with B-DNA via intercalation at a low ratio under a low ionic strength, 1 mM sodium phosphate. On the other hand, the interaction with A-DNA (80 v/v % ethanol–water system) occurs in a nonintercalating manner. This difference might be because the structural conformations, such as the groove of A-DNA, are not as deep as in B-DNA and the bases are much more tilted. In the case of Co-TMPyP, porphyrin binds preferably via an outside self-stacking mode with B- and A-DNA.

Experimental Data and New Binary Interaction Parameters for Ethanol-Water VLE at Low Pressures Using NRTL and UNIQUAC

Separation of ethanol from many sources, mainly renewable sources, is commonly achieved by atmospheric distillation. Even so, there is new technologies for ethanol separation and purification: pressure-swing distillation, extractive distillation, adsorption with molecular sieves and vacuum membrane distillation. The design, rating and optimization of these process technologies requires a reliable and universal thermodynamic modeling approach capable of represents the ethanol-water system properties, and in particular the vapor-liquid equilibrium (VLE) near the azeotropic point. This study resume experimental data of VLE for ethanol-water system at vacuum pressures (13.15-101.32 kPa) and its corresponding thermodynamic consistency test results using the Redlich-Kister method. The parameters and constants for the detailed thermodynamic modeling of the ethanol-water system using polar fluid Soave-Redlich-Kwong equation of state (polar-SRK) are resumed, as well as the standard binary interaction parameters for NRTL and UNIQUAC excess Gibbs energy models commonly used for the simulations involved in the chemical process engineering activities. This study contains the regression of new binary interaction parameters in a temperature dependent form compatible with the most process simulation software, for NRTL and UNIQUAC, and its validation using experimental data for azeotropic points at different low pressures with errors of less than 1% for temperature and ethanol molar fraction in vapor phase estimation. The new parameters were tested using isobaric experimental data for VLE at 3 under-atmospheric pressures obtaining correlation coefficient (R 2 ) values of about 1. The calculations were performed using python 3.4® codes developed and supplied by S&SE and Aspen properties® V8.6 provided by the Universidad Nacional de Colombia.

Synthesis, Characterization of Nano-β-Tricalcium Phosphate and the Inhibition on Hepatocellular Carcinoma Cells

It is difficult to synthesize nano-β-tricalcium phosphate (nano-β-TCP) owing to special crystal habit. The aim of this work was to synthesize nano-β-TCP using ethanol-water system and characterize it by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Malvern laser particle size analyzer, and transmission electron microscope (TEM). In addition, the inhibitory effect of nano-β-TCP on human hepatocellular carcinoma (HepG2) cells was also investigated using MTT assay, lactate dehydrogenase (LDH) leakage test, and 4′-6-diamidino-2-phenylindole (DAPI) staining. The results showed that negatively charged rod-like nano-β-TCP with about 55 nm in diameter and 120 nm in length was synthesized, and the average particle size of nano-β-TCP was 72.7 nm. The cell viability revealed that nano-β-TCP caused reduced cell viability of HepG2 cells in a time- and dose-dependent manner. These findings presented here may provide valuable reference data to guide the design of nano-β-TCP-based anticancer drug carrier and therapeutic systems in the future.

SOLVENTS EFFECT ON THERMAL STABILITY AND ELECTROCHEMICAL BEHAVIOUR OF GRIFFONIA SIMPLICIFOLIA EXTRACTS AS STEEL CORROSION INHIBITOR IN ACIDIC ENVIRONMENT

Different solvents were used to extract Griffonia simplicifolia and tested corrosion inhibitors for as X80 steel in 1 M HCl solution. The corrosion tests were conducted by thermo-gravimetric analyses (TGA), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) while the surface morphologies were checked by scanning electron microscopy (SEM). The essence was to investigate the effects of the solvents on the yield, phytochemical profile, corrosion inhibition properties and thermal stability of the extracts. The highest yields of 63.24 g kg -1 and 51.63 g kg -1 were obtained with seeds (SEGS) and leaves (LEGS) extracts respectively in ethanol-water (1:1) system. Acetone extract showed presence of all the tested phytochemicals namely alkaloids, tannins, saponins, glycosides, steroids and terpenoids. The highest inhibition efficiencies of 95.86 % (SEGS) and 82.14 % (LEGS) were obtained with acetone extracts. Acetone extract was also most thermally stable being 66.4 % (SEGS) and 50.05 % (LEGS) efficient at 90 °C, followed by ethanol extract while methanol extract was least stable and least efficient. Inhibitors act as mixed type and their addition increased charge transfer resistance and decreased corrosion current density with respect to the free acid solution. Micrographs of the steel surface in some systems show evidence of slight surface protection by the inhibitors. It has been inferred from this study that both acetone and ethanol are better solvents for extraction of Griffonia simplicifolia based corrosion inhibitors.

Modelling of Ethanol Fermentation Coupled with Product Recovery by Pervaporation

Bioethanol is the most important biofuel produced by fermentation of sugars from various biomass types. The main disadvantages associated to this process consist in the negative effect of high ethanol concentration on the cell growth and in the separation cost of ethanol-water system resulted in the fermentation process. Sugar fermentation using Saccharomyces cerevisiae yeast coupled with bioethanol recovery by pervaporation has been modeled and simulated in this paper. In order to avoid the clogging of pervaporation membrane, the yeast cells were previously retained into an ultrafiltration unit. Three operating modes were analyzed and compared, i.e., classical batch fermentation (BF), batch fermentation coupled with external ultrafiltration and pervaporation (BFPV), and fed batch fermentation coupled with external ultrafiltration and pervaporation (FBFPV). Surface areas of ultrafiltration and pervaporation units were selected as process control variables.