Pure Ethanol Solution Research Articles

Pyrazine as a More Efficient Luminophore than Benzene for Producing Red-Shifted and Enhanced Photoluminescence.

The development of organic photoluminescent (PL) materials with red-shifted and enhanced emissions is beneficial to promoting their applications. Luminescent materials based on aromatic heterocycles (e.g., pyrazine) usually have red-shifted and enhanced photoluminescence compared with phenyl-based luminescent materials. In this work, the photoluminescence behaviors of pyrazine and its derivatives (o-dichloro-, o-dicyano-, and dichlorodicyano-substituted) are compared with those of benzene and its derivatives. All compounds exhibit fluorescence emissions ranging from blue to yellow, and the fluorescence emissions of pyrazinyl compounds are more red-shifted than those of phenyl compounds. Except for the o-dicyano-substituted compound, pyrazinyl compounds exhibit stronger fluorescence emissions than corresponding phenyl compounds in both pure substances and ethanol solutions. In addition, both 5,6-dichloro-2,3-dicyanopyrazine (P4) and 4,5-dichloro-1,2-dicyanobenzene (B4) exhibit room temperature phosphorescence, and the maximum delayed emission wavelength is red-shifted from 575 nm of B4 to 637 nm of P4. The energy gaps between the highest occupied molecular orbital and the lowest unoccupied molecular orbital of the monomers of pyrazinyl compounds are reduced by 0.07-1.37 eV compared with the monomers of phenyl compounds, which is the fundamental reason for the red-shifted emissions of the pyrazinyl compounds. Moreover, compared to B4, the smaller molecular spacing in the P4 crystal structure facilitates interlayer electron transfer and hence the formation of more extended through-space conjugation, resulting in the red-shifted emission of P4. This work proves that pyrazine is a more efficient luminophore than benzene for constructing PL compounds with longer emission wavelengths and higher quantum yields, which are important in guiding the design and preparation of organic PL materials.

Экстрагирование гидрофильных компонентов кожуры и жома плодов граната

Pomegranate (Punica granatum L.) processing focuses on the extraction of polyphenols from peel. However, pomegranate peel is also rich in other biologically active water-soluble components, and their commercial extraction remains understudied. The research objective was to evaluate the degree of extraction of hydrophilic substances, such as simple sugars, organic acids, and polyphenols, from raw pomegranate peel and pulp under different experimental conditions in order to select the optimal extraction parameters.
 The study featured pomegranates of the Iridanaly variety (Geokchay, Azerbaijan). Raw peel and pulp were crushed to the state of a coarse gruel. Extraction occurred by maceration at a hydromodulus of 1:2 and a temperature of 40 or 60°C with pure water and aqueous ethanol solutions (10–14 % vol.). The process lasted 30, 60, or 90 min in one or two stages with separate extraction at each stage. The research involved standard physicochemical methods.
 In 31.0 ± 2.0 g/100 g of dry peel, the hydrophilic fraction accounted for 85.32%; in 35.7 ± 2.8 g/100 g of dry pulp, it was 59.36%. Only 54.6% solids were extracted from raw peel after 30 min of extraction with pure water at a hydromodulus of 1:2 and 60°C. Pomegranate peel contained hydrophilic colloids, which caused water absorption and reduced the yield. The optimal extraction included an aqueous solution of ethanol with an ethanol concentration of 10–14 % vol. and two thirty-minute stages. The coagulating effect of ethyl alcohol on water-soluble pectin made it possible to increase the degree of extraction of water-soluble substances to 83.93 and 91.4% of their initial content in raw peel and raw pulp, respectively. Such extraction yielded 4 kg of mixed extract from 1 kg of raw pulp. The extract was boiled under vacuum and yielded 260 g of concentrate with 60 wt.% solids, including 46.70 g/100 g simple sugars, 4.73 g/100 g organic acids, 3.70 g/100 g polyphenols, and 10.10 mg/100 g vitamin C.
 The extraction of raw pomegranate peel and pulp with aqueous ethanol (10–14 % vol.) provided the maximal degree of extraction of hydrophilic substances and facilitated the separation of the resulting extracts. However, strong alcohol solutions may increase the cost of distillation of alcohol from the extract. To eliminate this shortcoming, the extraction can be carried out with pure water and a pectolytic enzyme.

Artificial visible light-induced H2O2 production using polymeric K/O-doped carbon nitride as a catalyst

In an attempt to improve the decrease in H2O2 yield, resulting from slow electron transfer, availability of limited active sites for reaction, and low O2 activation of pristine polymeric carbon nitride (PCN), we fabricated a K/O-modified PCN photocatalyst with a high specific surface area and high O2 activation ability. A synergy between K and O dopants in PCN aided in reducing the reaction energy barrier of the •OOH intermediate species, thereby allowing PCN to exhibit a high H2O2 yield under white LED light 4428.3 μmol g-1h−1), almost 28 times higher in comparison to that obtained for the pristine PCN. The solar-to-chemical conversion (SCC) efficiencies in the presence of modified PCN were respectively equal to 0.05 % and 0.52 % under white LED light in pure water and ethanol solution (ethanol, 10 vol%). Additionally, the modified PCN exhibited a quite wide optical response. The apparent quantum yields (AQYs) of our modified PCN in ethanol were equal to 23.52 % and 1.19 % at 385 and 520 nm, respectively. Polymeric K/O-doped carbon nitride can therefore be utilized as a potential catalyst for artificial visible light-induced H2O2 production.

The role of hydrogen bonds in diluted ethanol solutions of cyclohexane and dimethylformamide

The aim of this work is to determine molecular association in solutions of cyclohexane-ethanol and dimethylformamide-ethanol. The refractometric method and Fourier transform infrared spectroscopy used to determine the optical features of the concentration characteristics of diluted ethanol solutions of cyclohexane and dimethylformamide. It was found for the first time that at some concentrations the hydrogen bond is stronger than for a pure ethanol solution. The first maximum of the excess refractive index of solutions is formed at a concentration of 0.02 mole fraction of cyclohexane and dimethylformamide, which is in good correlation with IR spectroscopy, indicating the largest number of formed hydrogen bonds.

Detection technique for vitamin D3 using Er-doped TiO2 nanowire-based UV photodetector

Vitamin D3 acts as a crucial biomarker for various diseases. Current methods for vitamin D3 detection are time-consuming, expensive, and require trained personnel. We report a simple and cheap photodetector (PD)-based vitamin D3 detection technique for the first time using Ag nanoparticles-covered Er-doped TiO2 nanowires. The operational stability of the device was tested under the dark as well as the UV light illumination. Vitamin D3 solution produced absorption bands at 222 and 280 nm, respectively. The PD current density varied from 1.29 × 10 − 4 A / cm2 to 1.74 × 10 − 4 at −4 V for pure ethanol solution and 20 pg / ml D3 solution, respectively (under 220 nm illumination). The average absolute current values were reduced from 3.25 nA (220 nm) and 2.9 nA (340 nm) for 5 pg / ml to 2.95 nA (220 nm) and 2.54 nA (340 nm) for 30 pg / ml D3 solution, respectively. The current gradually increased up to 3.34 nA (220 nm) and 2.7 nA (340 nm) as the concentration was increased up to 80 pg / ml. The PD current/vitamin D3 concentration decreases exponentially from 0.58 to 0.03 nA / g / ml) for 5 and 80 pg / ml, respectively, under 220 nm excitation, from which an unknown concentration of vitamin D3 can be obtained.

Investigation of solvated calcium dication structure in pure water, methanol, and ethanol solutions by means of K and L2,3-edges X-ray absorption spectroscopy

The interaction of an ion with surrounding solvent molecules is revealed by X-ray absorption spectroscopy in transmission mode for the case of calcium dication dissolved in pure water, methanol and ethanol at the Ca K and L2,3-edges. The near-threshold K-shell excitation leads to two distinct solvent-dependent features, the Ca 1s to 3d and 4p electronic transitions, clearly indicating the ligand field decreases as water is changed to methanol and methanol to ethanol. On the other hand, the Ca L2,3-edge excitation leads to small changes in the absorption spectra and the peak assignment – mostly in terms of Ca 2p to eg and t2g transitions for each of the two spin orbit components – is strongly depending on the geometry of the first solvation shell around the dication and on the magnitude of the ligand-field multiplet effects. Our interpretation is supported by ab-initio quantum chemical calculations of the solvent dependence of chemical shifts for the Ca 3d and 4p unoccupied levels of the 1s and 2p excited states, performed on a small cluster including the nearest neighbor solvent molecules surrounding the Ca dication assuming a cubic (8-fold) solvent coordination.

The terahertz metamaterials for sensitive biosensors in the detection of ethanol solutions

Metamaterials have attracted much attention due to their subwavelength characteristics, especially in the field of unlabeled refractive index sensing. Because biomolecular molecules have special biological fingerprint spectra in terahertz band, high sensitivity sensor components can be realized by using the special electromagnetic response of metamaterials. In this paper, a novel biosensor based on electromagnetic induced reflection is designed. We find that the asymmetrically fractured double-ring resonator can effectively enhance the fano-resonance of electromagnetic induction reflection, where the resonance position occurs at 1.57 THz. Oscillating Lorentz model shows that when the resonant detuning continues to increase, the bright mode and the dark mode are strongly coupled. When the light mode decreases, the radiation loss also decreases, which induces the decrease of resonance ability. The sensitivity of pure ethanol solution (analyte) under 5μm coating thickness is 103.7 GHz/RIU, 107.1 GHz/RIU and 112.05 GHz/RIU, respectively. The sensitivity and full width at half maximum (FWHM) of the sensor are studied from the perspectives of analyte concentration, thickness, and proportion, respectively. The results show the great potential of electromagnetic metamaterials as sensitive sensors in biological solution detection.

Ethanol conversion to selective high-value hydrocarbons over Ni/HZSM-5 zeolite catalyst

Bio-ethanol is a renewable fuel and can be converted to high-values chemicals. This study showed that more aromatics and gas products could be obtained at a low weight hourly space velocity (WHSV) than that at high WHSV using HZSM-5 and Ni/HZSM-5 catalysts. A low WHSV offered an increased tendency to build up aromatics and paraffins. Real bio-ethanol broth was tested and gave the similar result as pure ethanol solution. That catalysts could retain full catalytic activity after 168 h in reaction provides evidence for their long stability. This study advantageously demonstrates a promising approach to generate high-value products from bio-ethanol.

A phenanthro[9,10-d]imidazole-based optical sensor for dual-responsive turn-on detection of acidic pH and Cu2+ in chicken blood and living cells

A phenanthro[9,10-d]imidazole-based organic optical sensor (PIQPy) for dual-responsive turn-on detection of both acidic pH and Cu2+ in semi-aqueous media was described. PIQPy was weak fluorescence (nearly turn-off) in pure ethanol solution but exhibited typical aggregation-induced emission phenomenon (moderate turn-on) in water/EtOH mixture. More interestingly, PIQPy further displayed a dual enhancement (strong turn-on) for both acidic pH and Cu2+ with highly fluorescent intensity. pKa value of PIQPy for pH responding was 6.89, which suggests that PIQPy was an ideal biosensor for pH sensing. In addition, the super lower limit of detection for Cu2+ were found to be 37.69 nM which also nearly 500-fold lower than Cu2+ concentration in blood (15.7–23.6 μM). Therefore, PIQPy was successfully used to detect Cu2+ in chicken blood. Furthermore, these dual-responsive turn-on signals to both acidic pH and Cu2+ were also successfully implemented in HeLa cells, which proved that PIQPy was capable of imaging pH fluctuations and simultaneous Cu2+ in living cells.

Synergistic Sorption of Mixed Solvents in Wood Cell Walls: Experimental and Theoretical Approach

The behavior of poplar wood and its components in water‐ethanol mixtures is investigated through a coupled experimental and theoretical approach including physico‐chemical and dynamic mechanical analyses and molecular dynamics simulations. Affinity for water‐ethanol vapors, measured by isothermal gravimetric sorption experiments, features a maximum for mixed vapors. The longitudinal viscoelastic behavior of the same wood upon immersion in ethanol‐water solutions, measured by dynamic mechanical analysis, features a minimum in storage modulus and a maximum damping upon immersion in solutions of intermediate composition. Optical microscopy observation of solvent‐saturated samples evidences inter‐ and intra‐cellular disbonding in pure ethanol and ethanol aqueous solutions. Molecular dynamics simulations provide information on interactions of water‐ethanol solutions with models of cellulose microfibers and lignin. The relative solvation of cellulose microfibers by water and ethanol shows a nearly linear variation with the composition of the solution. In contrast, the accessibility of lignin dimers to the solvent presents a maximum at intermediate ethanol concentrations, in correspondence with a conformational transition of the dimer towards an extended conformation. The modelization of the interactions of cellulose and lignin in water‐ethanol solutions indicates a minimum of adhesion of the two components of wood in the presence of solutions with intermediate concentrations.

Role of solubility and solvation thermodynamics on the stability of l-phenylalanine in aqueous methanol and ethanol solutions

The solubilities of l-phenylalanine in aqueous alcohols such as methanol and ethanol were applied to find various solvation thermodynamic parameters like transfer Gibbs free energies and transfer entropies of solutions. The estimated results were correlated with other solvation and interaction parameters such as transfer free energy due to cavity forming interactions, dipole-dipole interactions, transfer enthalpy and total transfer free energy to find the actual transfer Gibbs free energies and entropies owing to chemical nature of interactions in solutions. These chemical transfer Gibbs interaction parameters were discussed to explain the overall stability of l-phenylalanine in pure solvents, aqueous methanol and ethanol solutions. In addition various thermophysical factors like molar density, molar mass, molar volume, isothermal expansibility and apparent dipole moment of aqueous cosolvent systems were also measured at 298.15 K.

Green synthesis of a dendritic Fe3O4 @Feo composite modified with polar C-groups for Fenton-like oxidation of phenol

In this work, a hierarchical dendritic Fe3O4@Fe0 composite modified with polar C-groups was obtained by electrodeposition and post-solvothermal methods. SEM, EDS, TEM, XRD, Zeta analysis and ESR were employed to study the structure and composition of catalyst, and the catalytic capability was evaluated by phenol degradation experiments. With the increase of water ratio in thermal solution, the composition of prepared catalyst changes into Fe3O4/Fe2O3 from Fe/Fe3O4, and the dendritic structure turns into particle-like structure. The phenol degradation experiments indicate the catalyst prepared in pure-ethanol solution possesses the optimal catalytic capability, which has a Fe@Fe3O4 core-shell structure with some polar C-groups on Fe3O4 outer layer. Under the condition of 0.18 g/L of catalyst dosage, 6 mmol/L H2O2 and pH = 4.0, the composite catalyst prepared in pure ethanol could remove 98% phenol for 5 min, greatly higher than dendritic bare Feo under the same condition. The enhancement of degradation efficiency by Fenton-like reaction might be ascribed to polar groups that facilitate the adsorption of H2O2, phenol and hydroxyl radicals and promote the transformation of FeIII to FeII on the catalyst surface. This work provides a new insight into the design and application of high-efficient Fe0-based Fenton-like composite catalysts for wastewater purification.

Structural, spectral, magnetic and thermal studies of 5-(thiophene-2-ylmethine azo) uracil metal complexes

Mono- and bimetallic 5-(thiophene-2-ylmethine azo) uracil complexes were prepared in a pure ethanol or ammoniacal solution. The complexes were characterized by elemental analyses, thermal analyses, magnetic moment and spectroscopic measurements. The infrared and 1H-NMR studies revealed that the ligand reacts with all metal ions in a neutral keto form. Also, the ligand behaves as a tridentate or bidentate and coordinated with metal ions by ONS, NS and ON donors atoms, where azomethane nitrogen atom, and/or sulfur atom of thiophene ring and oxygen atom of uracil ring are participated to construct mononuclear Co(II), Ni(II), Zn(II), bimetallic Cd(II); mononuclear Cu(II) and Mn(II) complexes, respectively. However, in case of bimetallic Co(II) 7 and Ni(II) 8 ammine complexes, the ligand bridge is considered to indicate the ligand has tetra- and pentadentate character toward two metal ions, respectively. The magnetic moment values and the Nujol mull electronic spectra showed that all complexes have an octahedral geometry, except Cu(II) complex, 4 has a square planar structure. All the thermal decomposition processes led to formation of metal oxides. The hydrated complexes displayed a higher thermal stability than that of ammine complexes. Theoretical investigations have also been carried out at CAM-B3LYP/LANL2DZ to study the structure of the ligand and its Mn(II) complex. The results confirmed the experimental discussion.

Acoustical studies of synthesized α,β-unsaturated ketones in ethanol and different percentage composition of DMSO in ethanol

In the present investigation chalcones were synthesized by aldol condensation of acetophenone with aromatic aldehyde in basic medium and products were characterized by 1H NMR and 13C NMR spectra. These synthesized chalcones were then dissolved in pure ethanol and ethanol solutions containing 10%, 30% and 50% dimethyl sulphoxide (DMSO) to obtain binary and ternary solutions of various concentrations. Density, ρ, viscosity, η and speed of sound, u of these solutions were measured over a wide range of temperature (298.15K to 308.15K). Various acoustical parameters like adiabatic compressibility, intermolecular free length, acoustic impedance, relaxation time and free volume have been evaluated by using the measured values of density, viscosity and speed of sound. The obtained results are interpreted in terms of molecular interactions that give us an idea of structure-making or structure-breaking ability of solute molecules in different solvents.

A bottom-up strategy for exfoliation-free synthesis of soluble α-Ni(OH)2 monolayer nanosheets on a large scale

α-Ni(OH)2 monolayer nanosheets were successfully synthesized in pure ethanol solution with high yield using NaOH as precipitant, based on a facile one-step “bottom-up” strategy.

A Study on Spirituous Liquor Efficiency Using Direct Alcohol Fuel Cell

The electro-oxidation of 40 degree of alcohol as a local-commercial of spirituous liquor in Thailand compared with pure ethanol solution on the metal catalyst of PtSn/C was carried out. With using the 5 cm2 anode electrode of PtSn/C catalyst, the direct alcohol fuel cell was employed and then fed with 1 M of spirituous liquor at flow rate of 1 ml/min under operating condition of atmospheric pressure. The results from an output electrical power of 40 degree liquor fed into direct alcohol fuel cell (celled 40DFC) indicated that, at the initial time, the spirituous liquor provided the higher power density of 6 mW/cm2 compared with ethanol solution (celled DEFC) at the same concentration. For the cell open circuit voltage (OCV) using the spirituous liquor as fuel, it was 0.63 V which slightly lower than ethanol solution one. Nevertheless, 15 minutes left after applying the liquor, the cell performance was dramatic dropped due to the poisoned species of sulfur contained in liquor. The anode catalyst performance loss was also proved by using hydrogen gas for rechecking of the permanent degradation of fuel cell caused by feeding liquor onto the PtSn catalyst surface.

An appealing photo-powered multi-functional energy system for the poly-generation of hydrogen and electricity

This paper focuses on a photo-powered poly-generation system (PPS) that is powered by the photocatalytic oxidation of organic substrate to produce hydrogen energy and electrical energy synchronously. This particular device runs entirely on light energy and chemical energy of substrate without external voltage. The performance measurements and optimization experiments are all investigated by using the low concentration of pure ethanol (EtOH) solution. Compared with the conventional submerged reactor for the photogeneration of hydrogen, the hydrogen and the electric current obtained in the constructed PPS are all relatively stable in experimental period and the numerical values detected are many times higher than that of the former by using various simulated ethanol waste liquid. When using Chinese rice wine as substrate at the same ethanol content level (i.e., 0.1 mol L−1), the production of hydrogen is close to that of the pure ethanol solution in the constructed PPS, but no hydrogen is detected in the conventional submerged reactor. These results demonstrate that the constructed PPS could effectively utilize light energy and perform good capability in poly-generation of hydrogen and electricity.

Increase of methane formation by ethanol addition during continuous fermentation of biogas sludge.

Very recently, it was shown that the addition of acetate or ethanol led to enhanced biogas formation rates during an observation period of 24h. To determine if increased methane production rates due to ethanol addition can be maintained over longer time periods, continuous reactors filled with biogas sludge were developed which were fed with the same substrates as the full-scale reactor from which the sludge was derived. These reactors are well reflected conditions of a full-scale biogas plant during a period of 14days. When the fermenters were pulsed with 50-100mM ethanol, biomethanation increased by 50-150%, depending on the composition of the biogas sludge. It was also possible to increase methane formation significantly when 10-20mM pure ethanol or ethanolic solutions (e.g. beer) were added daily. In summary, the experiments revealed that "normal" methane production continued to take place, but ethanol led to production of additional methane.

ZnO-coated SMS structure interrogated by a fiber ring laser for chemical sensing

A zinc oxide (ZnO)-coated single mode–multimode–single mode fiber (SMS) structure interrogated by a fiber ring laser has been developed as a chemical sensor. Response to relative humidity (RH) and ethanol volatilization was evaluated by tracking the wavelength shifts of the output laser line in different moisture environments and ethanol solutions, respectively. For humidity sensing a linear response with a measurement range of 4–96% RH, and a sensitivity of 0.06 nm per %RH were obtained. As for ethanol volatilization sensing obvious wavelength blue shift was observed for the sensor immersed in 50% and 62% ethanol solution, while no variation could be detected in pure ethanol solution (purity larger than 97%). With the advantages of low cost, ease of fabrication and sensitive response, ZnO-coated SMS interrogated with a fiber ring laser was demonstrated to be an effective sensor for humidity and ethanol volatilization sensing.

On-line microwave-based preconcentration device for inductively coupled plasma atomic emission spectrometry: Application to the elemental analysis of spirit samples

A microwave-based thermal nebulizer (MWTN) has been employed for the first time as on-line preconcentration device in inductively coupled plasma atomic emission spectrometry (ICP-AES). By the appropriate selection of the experimental conditions, the MWTN could be either operated as a conventional thermal nebulizer or as on-line analyte preconcentration and nebulization device. Thus, when operating at microwave power values above 100W and highly concentrated alcohol solutions, the amount of energy per solvent mass liquid unit (EMR) is high enough to completely evaporate the solvent inside the system and, as a consequence, the analyte is deposited (and then preconcentrated) on the inner walls of the MWTN capillary. When reducing the EMR to the appropriate value (e.g., by reducing the microwave power at a constant sample uptake rate) the retained analyte is swept along by the liquid-gas stream and an analyte-enriched aerosol is generated and next introduced into the plasma cell. Emission signals obtained with the MWTN operating in preconcentration-nebulization mode improved when increasing preconcentration time and sample uptake rate as well as when decreasing the nozzle inner diameter. When running with pure ethanol solution at its optimum experimental conditions, the MWTN in preconcentration-nebulization mode afforded limits of detection up to one order of magnitude lowers than those obtained operating the MWTN exclusively as a nebulizer.To validate the method, the multi-element analysis (i.e. Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Pb and Zn) of different commercial spirit samples in ICP-AES has been performed. Analyte recoveries for all the elements studied ranged between 93% and 107% and the dynamic linear range covered up to 4 orders of magnitude (i.e. from 0.1 to 1000μgL−1). In these analysis, both MWTN operating modes afforded similar results. Nevertheless, the preconcentration-nebulization mode permits to determine a higher number of analytes due to its higher detection capabilities.