Vapor–liquid equilibria for ethyl acetate + methanol and ethyl acetate + ethanol mixtures: Experimental verification and prediction

This work aims of the determination of a series of vapor–liquid equilibrium (VLE) experimental data at low pressure (70 kPa) for binary mixtures of ethyl acetate with methanol and ethanol. The Fischer's ebulliometer was used for the measurements of VLE data. A complete series of equilibrium data was obtained such as pressure, temperature and compositions of the liquid and vapor phases (PTxy). The two VLE data sets were submitted to a thermodynamic consistence test, where the deviations were evaluated in all variables, using the UNIQUAC activity coefficient equation. The magnitude of the average deviations was within the experimental uncertainty satisfying the Gibbs–Duhen equation. The data sets were also used to test the prediction of the UNIFAC model in its original and modified editions and the results were also within experimental uncertainties. Then a series of binary systems containing alcohols (methanol and ethanol) and esters (methyl and ethyl acetate) were collected from the literature for testing systematically the capability of the UNIFAC contribution method for this type of mixtures.     

Magnetoelectric composite thick films of PZT–PMnN + NiZnFe2O4 by aerosol-deposition

Highly dense magnetoelectric composite films with 10 μm-thick of high piezoelectric voltage coefficient material, 0.9Pb(Zr₅₇Ti₄₃)O₃–0.1Pb(Mn_1/3Nb_2/3)O₃ (PZT–PMnN) and magnetostrictive material, Ni_0.8Zn_0.2Fe₂O₄ (NZF), were fabricated on a platinized Si substrate using aerosol deposition (AD). With increasing magnetic NZF content, dielectric and ferroelectric properties were gradually decreased while magnetizations were improved. The 20% NZF added composite thick film were found to exhibit the maximum ME coefficient. This optimal NZF content is the same as that of bulk ME composite materials. It is noticeable that AD can control the content ratio of ME composite films by controlling the powder composition. The fabricated ME composite films have high ME voltage coefficient coupling because of high density without severe inter-reactions of two phases.     

Prediction of Liquid Viscosities of Petroleum Fractions

   A general equation is proposed for predicting the liquid viscosities of petroleum fractions based on a generalized pseudocompound method in which pure hydrocarbons and undefined hydrocarbon mixtures or petroleum fractions are treated as a hypothetical pure substance called pseudocompound which is characterized only by a boiling point and a density . The equation is tested by using the liquid viscosities of the petroleum fractions of typical American crude oils and crude oils from major oil producing areas. Good agreement between the predicted and experimental viscosities for the petroleum fractions is obtained.     

First example of PMMA-supported and highly luminous color-purity red-light metallopolymer based on a tris-β-diketonate Zn2 +-Eu3 +-complex

Through the copolymerization of a complex monomer [Zn(L)(4-vinyl-Py)Eu(TTA)₃] (2; H₂L = N,N′-bis(salicylidene)cyclohexane-1.2-diamine; 4-vinyl-Py = 4-vinyl-pyridine and HTTA = 2-thenoyltrifluoroacetonate) with MMA (methyl methacrylate), the first example of PMMA-supported and highly luminous (Ф_Eu^L = 63.1%) color-purity red-light metallopolymer poly(MMA-co-2) based on a tris-β-diketonate Zn^2 +-Eu^3 +-complex is obtained.     

Heteroepitaxial ZnO/sapphire (0 0 0 1) structure prepared by sol–gel process

ZnO thin films were grown on sapphire (0 0 0 1) substrates by sol–gel process and their structural and optical properties were characterized in detail. High-quality texture was obtained by using precursor solution of zinc acetate and ethanolamine in 2-methoxyethanol, pyrolyzed at 300 °C, then heated at 500 °C, and finally annealed at 750 °C. Highly c-axis oriented ZnO films were confirmed by X-ray θ–2θ scan. A relatively high transmittance in the visible spectra range and clear absorption edge of the film were observed. Epitaxial relationship between ZnO and sapphire and photoluminescence of the film were examined by using a X-ray pole-figure analysis and He–Cd laser. Near-band-edge emission with a deep-level emission was observed.     

Characteristics of absorption/regeneration of CO2–SO2 binary systems into aqueous AMP + ammonia solutions

To examine the characteristics of absorption and regeneration, the simultaneous removal efficiency of carbon dioxide/sulfur dioxide (CO₂/SO₂), the CO₂ absorption amount, and the CO₂ loading value of an ammonia (NH₃) solution added to 2-amino-2-methyl-1-propanol (AMP) were investigated using the continuous absorption and regeneration process. The performances of this system, such as the removal efficiency of CO₂ and SO₂, absorption amount, and CO₂ loading, were evaluated under various operating conditions. Based on the experimental study, the optimum conditions were a liquid circulation rate of 90 mL/min and gas flow rate of 7.5 L/min. The addition of NH₃ into aqueous AMP solution increased the absorption rate and loading ratio of CO₂ and raised the removal efficiencies of CO₂ and SO₂ to over 90% and over 98%, respectively.     

ZrSi2–SiC composite obtained from mechanically activated ZrC + 3Si powders by pulsed current activated combustion synthesis

Dense nanostructured ZrSi₂–SiC composite was simultaneously synthesized and consolidated by pulsed current activated combustion synthesis (PCACS) within 2 min in one step from mechanically activated powders of ZrC and 3Si. Highly dense ZrSi₂–SiC with relative density of up to 97% was produced under simultaneous application of a pressure of 60 MPa and the pulsed current. The average grain size and mechanical properties of the composite were investigated.     

Demixing pressures of hydroxy-terminated poly(dimethylsiloxane)–carbon dioxide binary mixtures at 313.2 K, 323.2 K and 333.2 K

The phase behavior of PDMS(OH)–CO₂ binary mixtures was investigated. Two different molecular weight PDMS(OH) were utilized and the demixing pressures were determined at three temperatures for a wide composition range. Both of these polymers were found to form miscible mixtures with CO₂ at all compositions at pressures lower than 31 MPa in the temperature range 313.2–333.2 K. Depending on the composition of the binary mixtures, two types of phase separation was observed during depressurization; the bubble point and the cloud point. In addition, at specific weight fractions a color change was also observed which was attributed to the mixture critical point. The demixing pressures were observed to increase with temperature and decrease with increasing polymer weight fraction. In addition, higher demixing pressures were obtained for the higher molecular weight polymer mixtures. The bubble point data were modeled by using Sanchez–Lacombe equation of state (SLEoS) and the binary interaction parameters were regressed at the studied temperatures. It was observed that the binary interaction parameters decreased with increasing temperature.     

Heterogeneous oxidation of 2-octanol on 5 wt%Pt–1 wt%Bi/Carbon catalyst

The low activity of 5%Pt–1%Bi/Carbon for the oxidation of 2-octanol at atmospheric pressure and 343 K was investigated. Using solvents such as heptane and p-xylene, it was shown that the reaction rates decrease dramatically shortly after the start of the reaction due to poisoning by product adsorption. Hence this work investigates the effect of using different solvent mixtures on the oxidation reaction of 2-octanol with 5%Pt–1%Bi/Carbon. Mixtures with different volumetric ratios of heptane and dioxane were investigated to find the best composition capable of effectively removing the adsorbed amphiphilic ketone. It is apparent that the reaction rate is correlated with the adsorption coefficient of ketone on the catalyst, such that the maximum reaction rate occurs at the lowest ketone adsorption coefficient, corresponding to a concentration of 16–18%v/v dioxane. A model based on a Langmuir–Hinshelwood mechanism has been successfully fitted to the experimental rates.     

Crystal structure,mixture behavior,and microwave dielectric properties of novel temperature stable (1 − x)MgMoO4 − xTiO2 composite ceramics

Novel temperature stable MgMoO₄–TiO₂ microwave dielectric ceramics were prepared by a solid state reaction process at low temperature (950 °C). As TiO₂ content increases, the relative permittivity increases while the Q × f value decreases, and the variation mechanisms are proposed, respectively. The temperature coefficient of resonant frequency (τ_f) shifts to the positive direction as TiO₂ is added. The mixture mechanisms of τ_f value for two-phase composite materials are supposed. A near-zero τ_f value (3.2 ppm/°C) is obtained when x = 0.3, with ε_r = 9.13 ± 0.03 and Q × f = 11,990 GHz. The 0.7MgMoO₄–0.3TiO₂ composites are considered to be appropriate as a low temperature co-fired ceramic material for microwave wireless communication applications.     

Phase evolution and chemical durability of Zr1-xNd xO2-x/2 (0 ≤ x ≤ 1) ceramics

A series of Zr_1-xNd _xO_2-x/2 (0 ≤ x ≤ 1) ceramics was prepared by solid-state reaction method. The effects of Nd content on the phase evolution were investigated. The chemical durability of resulting waste forms was also examined. The results show that the ceramics with x < 0.1 show monoclinic and cubic zirconia phase, with 0.2 ≤ x < 0.4 exhibit a single cubic phase, with 0.4 ≤ x ≤ 0.6 exhibit a single pyrochlore phase, with 0.6 < x < 0.8 exhibit a single cubic phase and remain cubic phases and hexagonal Nd₂O₃ when 0.8 ≤ x ≤ 1. The unit cell parameters of the Nd-doped zirconia samples increase as the Nd content increases. Moreover, the normalized element release rates of Nd element in Nd-doped zirconia ceramics firstly decrease with leaching time and almost no change after 21 days (∼0⁻⁶ g m⁻² d⁻¹), demonstrating its good chemical durability.     

Oxyacetylene ablation of (Hf0.2Ti0.2Zr0.2Ta0.2Nb0.2)C at 1350 − 2050 °C

Ablation resistance of a multi-component carbide (Hf_0.2Ti_0.2Zr_0.2Ta_0.2Nb_0.2)C (HTZTNC) was investigated using an oxyacetylene flame apparatus. When the surface temperature of the HTZTNC was below 1800 °C, (Nb, Ta)₂O₅, (Hf, Zr)TiO₄, and (Hf, Zr)O₂ were found to be the main oxidation products, while at higher temperature, formation of (Hf, Zr, Ti, Ta, Nb)O_x was favored and its content gradually increased with the increase in ablation temperature. Based on the ablation results and thermodynamic simulation analysis, a possible ablation mechanism of HTZTNC was proposed. Active oxidation of TiC and outward diffusion of TiO were demonstrated to occur during the ablation process, which constitute the critical steps for the ablation of HTZTNC. These results can contribute to the design of ablation resistant ultra-high-temperature ceramics.     

Demulsification of Emulision Liquid Membrane by Wetting Coalescence Materials

  Demulsification of emulsified water-in-oil droplets was worked out with the employment of wetting coalescence materials. Demulsification is carried out in conventional stirred-column and packed-column. Among the four kinds of natural fibers and two kinds of inorganic materials tested, natural fiber A, originated from wood shavings was found to give the best performance of demulsification. The demulsification efficiency can exceed 96.5% when demulsification conditions are optimized. The packed-column showed much better performance both in terms of demulsification efficiency and repeated use of the recovered oil phase for extracting cadmium in simulated wastewater. Operating variables governing the demulsification efficiency were investigated.     

Microporous solid based solely upon an intermolecular NH ⋯ O and NH ⋯ Cl hydrogen bond network

A novel porous solid of ruthenium(II, III) dimer complex, [Ru₂(p-O₂CC₆H₄NHCO^tBu)₄Cl], constructed by intermolecularly linking the hydrogen bonds of NH ⋯ O and NH ⋯ Cl was synthesized and the porous structure was crystallographically determined. The dried crystalline solid shows a high BET surface area determined by measuring the adsorption of nitrogen gas and water vapor.     

Frequency and temperature dependent electrical properties of Ni0.7Zn0.3CrxFe2−xO4 (0 ≤ x ≤ 0.5)

Series of the ferrite samples with a chemical formula Ni_0.7Zn_0.3Cr_xFe_2?xO₄ (x = 0.0–0.5) were prepared by a sol–gel auto-combustion method and annealed at 600 °C for 4 h. The prepared samples have the cubic spinel structure with no impurity phase. As the Cr³⁺ content x increases, the unit cell dimensions decrease with an increase in Cr³⁺ content x. The crystallite size is decreases from 37 nm to 21 nm as the Cr³⁺ content increases from x = 0.0 to 0.5. Resistivity increases whereas dielectric constant decreases with an increase in Cr³⁺ content x. Maxima in the dielectric loss tangent versus frequency appear when the frequency of the hopping charge carriers coincides with the frequency of the applied alternating field. Dielectric constant and dielectric loss tangent increases with increase in temperature. Saturation magnetization of sintered samples showed higher values as compared to as-prepared sample. Curie temperature deduced from AC susceptibility data decreases with increasing x.