2-propanol Solution Research Articles

Synthesis of Aluminum-doped Zinc Oxide Nanowires Hydrothermally Grown on Plastic Substrate

We report the synthesis of undoped ZnO and Al-doped ZnO (ZnO:Al) nanowires grown using a two-step process: (a) preparation of the seed layer, and (b) growth of the nanostructures. In the first step, 10 mM solutions of zinc acetate dihydrate and 1-propanol were spin coated on polyethylene terephthalate (PET) substrate at 2000 rpm by 30 s. Vertical nanowires were then grown by dipping the substrates in an equimolar solution of zinc nitrate hexahydrate and hexamethylenetetramine. As doping source, aluminum nitrate nonahydrate powders were added in the solution. In the solutions, Al doping concentrations were established as 0.5 At %, 1.0 At %, 2.0 At % and 3.0 At %, respectively. The hydrothermal process were carried out with a commercially microwave at 140 W power setting. The nanowires were characterized optically and morphologically. XRD patterns show the presence of ZnO, Zn(OH)2 and Zn6Al2O9. Scanning electron microscopy analysis showed that the size of ZnO nanowires was 50 nm in diameter. The undoped ZnO and ZnO:Al nanowires bandgap energy was obtained from optical transmission spectra.

Peculiarities of azobenzene catalytic hydrogenation in 2-propanol aqueous solutions with acid or base additives

It is shown experimentally that the hydrogenation of azobenzenes over a nickel skeleton catalyst in 2-propanol aqueous solutions proceeds selectively with the formation of aniline. It is pointed out that during the reaction, considerable participation of hydrogen bonded with active centers of a catalyst surface was observed. The competitive character of adsorption between the initial azo compound and aniline formed as a result of reaction is established. It is concluded that purposeful change of the azo group hydrogenation rate is possible by introducing acid or base additives into 2-propanol aqueous solution.

Preparation and Characterization of Insulin-Loaded Lipid-Based Microspheres Generated by Electrospray

Electrospray has been recognized as an efficient technique for the fabrication of polymer micro and nanosystems and recently it was applied to lipids. The objective of this study was to assess the potential of electrospray for the encapsulation of insulin into lipid particles. Spherical particles of about 1 µm were obtained jetting a propanolic solution of palmitic or stearic acid and ethylcellulose or Pluronic F127 in a 10:1 or 20:1 (w/w) ratio under an electric field of 30 kV. Insulin was entrapped into the particles with high encapsulation efficiency by the formation of an ion-pair with sodium dodecyl sulphate. Far-ultraviolet circular dichroism spectroscopy indicated that electrospray did not modify the secondary structure of insulin. An in vitro prolonged release over 24 hours was observed after an initial burst effect. This study demonstrates that electrospray represents a viable new alternative for preparing in a single step peptide-protein loaded lipid based microspheres directly in powder form.

Hydrogen Generation by Pulsed Gliding Arc Discharge Plasma with Sprays of Alcohol Solutions

The formation rates and energy yields of H2 formed from methanol, propanol, and ethanol solutions exposed to a nonthermal pulsed plasma-gliding arc reactor equipped with a spray nozzle were determined. The H2 energy yield formation was the highest with Ar carrier and pure methanol giving 176 ± 25% kW h at the highest liquid flow rate. This value is higher than other reported plasma technologies and within error of the energy yields for more conventional thermal reforming. Liquid droplets can enhance energy yield; however, the low chemical yields of H2 suggest the need for reactor operation with a recycle stream.

Dependence of enthalpies of dissolution of β-alanyl-β-alanine on the composition of (water + alcohol) mixtures at 298.15 K

The dissolution enthalpies of β-alanyl-β-alanine in aqueous methanol, ethanol, 1-propanol and 2-propanol solutions with an alcohol content up to 0.4 mole fractions have been measured calorimetrically at T = 298.15 K. The standard enthalpies of dissolution, Δ sol H° and transfer, Δ tr H°, of β-alanyl-β-alanine from water into mixed solvents and the enthalpy coefficients of pair-wise interactions, h xy , of β-alanyl-β-alanine with alcohol solvent molecules have been calculated. The results are discussed in terms of solute–solute and solute–solvent interactions.

LET and dose rate effect on radiation-induced copolymerization of maleimide with styrene in 2-propanol solution

N 2-saturated 2-propanol solutions containing styrene and maleimide were irradiated by electron, proton, He and C-ion beams. The styrene–maleimide copolymer was produced by radical polymerization induced during irradiation. The effects of the radical distribution, which depends on the LET or dose rate, on the molecular weight and the polymer yield were discussed.

Dynamic Behaviors of Polypyrrole Actuators in Electrolyte Solution Mixed with 2-Propanol

It has been previously reported that dynamic behaviours of polypyrrole (PPy) soft actuators were improved when they were driven in aqueous solutions of an electrolyte, lithium bis(trifluoromethanesulphonyl)imide (LiTFSI) containing an optimised amount of 2-propanol. In this work, the influences of the potential sweep rate on electrochemical and creep strains of PPy actuators in aqueous LiTFSI electrolyte solutions with 2-propanol concentrations of 0 and 20% were investigated under the load stress of 0.3 MPa. The electrochemical strain rates in the 0% and 20% 2-propanol solution were found to be approximately 0.1% s−1 and 0.25% s−1, respectively, and they are nearly independent of the sweep rate between 10 and 25 mV s−1. These results suggest that TFSI anion penetration into the PPy films might be limited by the interactions between the PPy surface and the TFSI anions. The creep rate was more rapidly increased as time elapsed in the electrolyte solution containing 2-propanol than that in the electrolyte solution without 2-propanol, which was due to the swelling of PPy film in the electrolyte.

Reaction Mechanisms and Structural Characterization of the Reactive Intermediates Observed after the Photolysis of 3-(Hydroxymethyl)benzophenone in Acetonitrile, 2-Propanol, and Neutral and Acidic Aqueous Solutions

Nanosecond time-resolved resonance Raman (ns-TR(3)) spectroscopy was employed to investigate the photoinduced reactions of 3-(hydroxymethyl)benzophenone (1) in acetonitrile, 2-propanol, and neutral and acidic aqueous solutions. Density functional theory calculations were utilized to help the interpretation of the experimental spectra. In acetonitrile, the neutral triplet state 1 [denoted here as (m-BPOH)(3)] was observed on the nanosecond to microsecond time scale. In 2-propanol this triplet state appeared to abstract a hydrogen atom from the solvent molecules to produce the aryphenyl ketyl radical of 1 (denoted here as ArPK of 1), and then this species underwent a cross-coupling reaction with the dimethylketyl radical (also formed from the hydrogen abstraction reaction) to form a long-lived light absorbing transient species that was tentatively identified to be mainly 2-(4-(hydroxy(3-(hydroxymethyl)phenyl)methylene)cyclohexa-2,5-dienyl)propan-2-ol. In 1:1 H(2)O:CH(3)CN aqueous solution at neutral pH, (m-BPOH)(3) reacted with water to produce the ArPK of 1 and then underwent further reaction to produce a long-lived light absorbing transient species. Three photochemical reactions appeared to take place after 266 nm photolysis of 1 in acidic aqueous solutions, a photoreduction reaction, an overall photohydration reaction, and a novel photoredox reaction. TR(3) experiments in 1:1 H(2)O:CH(3)CN aqueous solution at pH 2 detected a new triplet biradical species, which is associated with an unusual photoredox reaction. This reaction is observed to be the predominant reaction at pH 2 and seems to face competition from the overall photohydration reaction at pH 0.

Impedance analysis for lateral field excited acoustic wave sensors

Lateral field excitation (LFE) acoustic wave devices have been recently investigated for liquid sensing applications. In the present study, the impedance characteristic of the LFE devices working in three operational modes was analyzed. The impedance of the pure-LFE coupling device at resonance can be equivalent to that of a Butterworth–Van Dyke circuit (BVD). It is found that the ( yxl)-16.51° LiTaO 3 LFE device has a much smaller resonance impedance in air due to the large LFE coupling factor and high dielectric constant. For the AT-cut quartz LFE device, there is no significant resonance peak observed in air due to the large resonance impedance. An equivalent circuit was present and used to analyze the impedance of the pseudo-LFE coupling device operating in liquids. It was well explained why the common used AT-cut LFE device is super sensitive to liquid electric property changes compared to a thickness-field-excited (LFE) device. The impedance changes in a single LFE-configuration device, working in a quasi-LFE mode, were also analyzed. And, the experiment results show that the impedance change at the resonance excited by the TFE is much larger than by the LFE in different concentrations of NaCl and 2-propanol water solutions.

Porous Biphasic Calcium Phosphate Scaffolds from Cuttlefish Bone

Cuttlefish bone is an inexpensive, readily available, morphologically complex natural material. It has an open structure, consisting of layers separated by pillar-like structures made of calcium carbonate. In this study natural bones from cuttlefish were successfully converted into porous biphasic calcium phosphate (BCP) scaffolds with a range of hydroxyapatite and β-tricalcium phosphate compositions. The process involved reaction with solutions of phosphoric acid (H3PO4) and 2-propanol, followed by heat treatment at high temperatures (up to 1300°C) in air. The crystalline composition of the BCP scaffolds could be controlled by varying the concentration of the H3PO4 in solution, and the duration of reaction time at room temperature. The original microstructure of the cuttlefish bone was preserved in the BCP scaffolds which featured >90% interconnected porosity. The structure consisted of continuous macroporous channels with smallest measured cross-sectional openings of 400 μm × 100 μm size. The BCP scaffolds prepared with 16 wt% H3PO4 solution had a measured compressive strength of 2.38 ± 0.24 MPa, with a characteristic noncatastrophic failure behavior. The ability to tailor the composition of these BCP scaffolds allows development of implants with controlled biodegradation, while their superior mechanical and microstructural properties stand to benefit efficient osteointegration and osteoinduction.

Degradation manner of polymer grafts chemically attached on thermally stable polymer films: swelling-induced detachment of hydrophilic grafts from hydrophobic polymer substrates in aqueous media

The degradation manner of graft-type polymer electrolyte membranes consisting of hydrophilic poly(styrenesulfonic acid) (PSSA) graft polymers (grafts) and thermally and mechanically stable hydrophobic polymer substrates such as crosslinked poly(tetrafluoroethylene) (cPTFE), poly(ethylene-co-tetrafluoroethylene) (ETFE), and poly(ether ether ketone) (PEEK) was examined in water at 85 and 95 °C. Severe weight loss was observed in PSSA-grafted cPTFE and ETFE films but not in a PSSA-grafted PEEK film. The decomposed extracts in water were characterized as PSSA during the whole course of degradation, clearly showing that the PSSA grafts detached from the fluorinated substrates without decomposition or scission of graft polymer chains. This is quite a new degradation manner for graft-type polymer electrolyte membranes. PSSA-grafted PEEK films showed severe weight loss in aqueous propanol solutions making PSSA grafts swell; clear correlation was observed between the degree of swelling in PSSA grafts and the film weight loss. The solubility parameters between grafts and the polymer substrates and small angle neutron scattering (SANS) data implied that the grafted films possessing a clear boundary at the interface resulted in significant weight loss. From the above observation, it should be concluded that hydrophilic PSSA grafts detach from hydrophobic polymer substrates due to swelling-induced stress at the interfacial boundary in the grafted films.

Estimation of the thermodynamic parameters of hydrogen bonding in alcohol solutions by the method of infrared spectroscopy

Hydrogen bonding (H-bonding) is a specific type of intermolecular interaction being formed for favorable mutual orientations of the interacting molecules. One of the authors had developed a model concept relating the H-bonding energy with the change of stretching vibrations Δν = νOH − νOH-NC of the alcohol OH-group in acetonitrile and acetone solutions: ΔH = 89.24Δν/ν0. The calculated H-bond energy was 10.45 kJ/mole for acetonitrile and ΔH = 12.12 kJ/mole for acetone. The results obtained are compared with the data calculated using the equilibrium constant of H-bonding reaction; they can also be used to calculate all other thermodynamic H-bond parameters by measuring the equilibrium constant K c in a certain temperature interval. The equilibrium constant is calculated from the Lambert–Bouguer–Beer law: $ {K_c} = \frac{{{C_{{\text{OH}} \cdots {\text{NC}}}}}}{{{C_{\text{OH}}} \cdot {C_{\text{NC}}}}} $ , ∆F = −RT ⋅ ln K c , ∆H = RT 2 ⋅ d(lnK c )/dT, and $ \Delta S = \frac{{\Delta H - \Delta F}}{T} $ . For the methanol solution in acetonitrile, Δν = 115 cm−1, ΔH = 10.87 kJ/mole, and K c = 42 L/mole. For the ethanol solution in acetonitrile, Δν = 118 cm−1, ΔH = 10.01 kJ/mole, and K c = 34 L/mole. For the propanol solution in acetonitrile, Δν = 110 cm−1, ΔH = 8.36 kJ/mole, and K c = 13 L/mole. All calculations are performed using the developed programs. The spectra are recorded on Perkin-Elmer-180 and Specord-84 IR-spectrometers. The values of the thermodynamic parameters calculated and estimated from K c – f(T) are in good agreement with each other and with the available literature data.

Thermodynamic analysis of alcohol effect on thermal stability of proteins

Thermal unfolding of ribonuclease A and α-chymotrypsinogen A was analyzed in various alcohol solutions of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, trifluoroethanol, and glycerol. The change in thermal unfolding ratio with temperature was described well by the van't Hoff equation and the melting temperature and the enthalpy of protein unfolding were obtained. The reciprocal form of the Wyman-Tanford equation, which describes the unfolded-to-folded protein ratio as a function of water activity, was applied to obtain a linear plot. From the slope of this plot and water activity, the stabilization free energy (ΔΔG) in a solution was calculated. This shows an important role of water activity in protein stability. ΔΔG was linearly dependent on alcohol concentration and m-values of alcohols for protein unfolding were obtained. This provides a theoretical basis for the linear extrapolation model (LEM). The m-values for alcohols were negative except for glycerol. The negative higher m-value for longer and linear chain alcohols suggested the important role of the disturbance of hydrophobic interactions as well as the hydrogen-bonding in the mechanism of protein destabilization by alcohols. The number of change in bound-alcohol molecules upon protein unfolding was also obtained.

English

English

PREPARATION OF MESOPOROUS TITANIA-SILICA AEROGELS BY CO<sub>2</sub> SUPERCRITICAL EXTRACTION

Stable anatase is attractive because of its notable functions for photocatalysis and photon-electron transfer. TiO2-nanoparticles dispersed SiO2 wet gels were prepared by hydrolysis of Ti(OC4H9n)4 and Si(OC2H5)4 in a 2-propanol solution with acid catalyst. The solvent in the wet gels was supercritically extracted using CO2 at 60 oC and 22 Mpa in one-step. Thermal evolution of the microstructure of the extracted gels (aerogels) was evaluated by XRD measurements, TEM and N2 adsorption measurements. The as-extracted aerogel with a large specific surface area, more than 365 m2g-1, contained anatase nanoparticles, about 5 nm in diameter. The anatase phase was stable after calcinations at temperatures up to 1000 oC, and BET specific surface area, total pore volume and average pore diameter did not change significantly after calcinations at temperature up to 800 oC. Keywords: Stable anatase, sol-gel, CO2 supercritical extraction.

Liquid transport through sulfonated cation-exchange membranes for different water–alcohol solutions

The aim of this work was to study the sorption and transport of different water–alcohol solutions (methanol, ethanol, 1-propanol and 2-propanol solutions) when a Nafion 117 membrane is separating them. It was observed that methanol permeability remains constant when varying the composition of the mixture. However, the permeability for the other alcohol solutions decreases from alcohol concentrations that are different for each alcohol. In addition, it was aimed to compare the behavior of membranes with different morphologies when they were separating water and water–alcohol solutions. Nafion 117 membrane and two sulfonated cation-exchange membranes (CR65-AZL-412 and MK-40) were used. Measurements of sorption and liquid transport were made using methanol and ethanol solutions. The uptake values for Nafion 117 membrane were higher than those obtained for CR65-AZL-412 and MK-40 membranes. The results reveal that, in contrast to Nafion membrane, a non-negligible water flux through CR65-AZL-412 and MK-40 membranes was observed along with the alcohol diffusion through them. For these two latter membranes the permeability could not be calculated since the alcohol diffusion is not the only physical process that should be considered. In spite of it, the alcohol and water fluxes through CR65-AZL-412 and MK-40 were estimated; turning out that the water flux was higher than alcohol flux.

THE STABILIZING OF ANATASE AEROGEL AT HIGH TEMPERATURE

Stable anatase is attractive to its notable functions for photo catalysis and photon-electron transfer. Stable anatase TiO­2 containing amorphous SiO2 aerogel was prepared by hydrolysis of Ti (OC3H7)4 and Si (OC3H7)4 in a 2-propanol solution with acid catalyst. The solvent in wet gels was supercritically extracted in CO2 at 60 oC and 22 Mpa. Thermal evolutions of the microstructure of the gels were evaluated by TGA-DTA, N2 adsorption and XRD. A stable anatase TiO2 containing amorphous SiO2 aerogel with a BET specific surface area of 365 m2/g and a total pore volume of 0.20 cm3/g was obtained as prepared condition. The anatase phase was stable after calcination up to 1000 oC, and BET specific surface area, total pore volume and average pore diameter did not change significantly after calcination up to 900 oC. Keywords: Supercritical extraction, sol-gel, aerogel, stable anatase structure

Determination and Correlation of the Solubility for Taurine in Water and Organic Solvent Systems

Using a laser monitoring technique, the solubility data of taurine in water and aqueous solutions of methanol, ethanol, and 2-propanol were measured over the temperature range from (274.05 to 353.0...

Degradation of hydroxymaleimide in 2-propanol by irradiation of energetic heavy ions (II)—N 2-saturated system

Hydroxymaleimide was irradiated in N 2-saturated 2-propanol solutions by high-energy heavy ions over a wide range of LET values. The differential G-values of the degradation of hydroxymaleimide by irradiation with the heavier ions were lower than those of the lighter ions for the same LET value. An opposite result obtained in the air-saturated system. The degradation efficiency was 1.5 times higher, when the dose rate was 1/10 times lower. When irradiated at an LET value lower than 8 eV/nm, the G-values converged to a value less than that obtained by γ-irradiation.

Dechlorination of organic chlorides with supported noble-metal catalysts in alkaline 2-propanol: effect of alcohol additives

m- and p-Chloroanisole were dechlorinated in the presence of a supported noble-metal catalyst (Pd/C or Rh–Pt/C) at 30 °C in a solution of 2-propanol containing NaOH. The addition of a small amount of methanol (1% v/v) to the 2-propanol solution greatly enhanced the rate of dechlorination of p-chloroanisole with Pd/C but retarded the rate with Rh–Pt/C. Other primary alcohols (1% v/v) enhanced m-chloroanisole dechlorination over Pd/C in the following order: methanol (enhancement factor, 10.6) > ethanol (3.3) > 1-propanol (2.1) > 1-butanol (1.0). When a secondary alcohol (2-butanol), tertiary alcohol (t-butyl alcohol), diol (ethylene glycol), or triol (glycerin) was added at 1% (v/v), the dechlorination rates were unchanged or retarded. We found that Pd/C was activated effectively by pretreatment with a solution of 2-propanol/methanol (99:1 v/v) containing NaOH.