Effect of the Location of the Detonation Initiation Point and the Position of the Air–Fuel Cloud on Explosion‐Field Parameters

The effect of the location of the initiation point on explosionfield parameters is studied numerically using as an example the detonation of a stoichiometric mixture of propane with air. The shape of the cloud of the mixture (toroid) and the ratio of its dimensions in calculations are typical of the volumes of air–fuel mixtures formed in accidents. The effect of the initiation point location within the cloud cross section was studied with variation in the position of the lower edge of the cloud above the underlying surface.     

Prediction of solid–gas equilibria with the Peng–Robinson equation of state

In many applications related to Supercritical-Fluid (SCF) technology, solids are dissolved in SC fluids. Experimental data are now available for many systems but cannot cover all cases of potential practical interest. The prediction of solid solubilities in SC fluids, often in the presence of co-solvents, is useful for rational design of SCF extraction and related processes. Recently, thermodynamics has made considerable steps towards describing complex systems (gases with polar compounds) at high pressures using the so-called Equation of State/Excess Gibbs Free Energy (EoS/G^E) models. The success of these models is so far restricted to Vapor–Liquid Equilibria (VLE) for which they have been primarily developed and tested. In this work we evaluate such a predictive model, the LCVM EoS, for solid–gas equilibria (SGE) including systems with co-solvents. LCVM is chosen due to its success for VLE of asymmetric systems such as CO₂ with heavy alkanes and alcohols. Successful predictions are obtained for several solids as well as for some systems with co-solvents, but the results are less satisfactory for complex, multifunctional solids. A discussion of several factors, which affect modeling of SGE with cubic EoS, is included.     

The Influence of the Alkyl Chain Length and Steric Effect on Stability Constants and Extractability of Co(II) Complexes with 1‐Alkyl‐4(5)‐methylimidazoles

Abstract

Extraction of Co(II) complexes has been studied with nine derivatives of 1‐alkyl‐4(5)‐methylimidazoles (with R=C₂H₃ to C₁₀H₂₁) from aqueous solution [I=0.5(KNO₃) at 25°C] with toluene, trichloromethane, and 2‐ethyl‐1‐hexanol. Stability constants of the complexes formed in the aqueous phase (β _c ) as well as partition constants (P _c ) of the extracted species were determined. It was demonstrated that both the stability constants and partition constants of the complexes increase with an increasing of the 1‐alkyl chain length. The tetrahedral together with octahedral complexes were formed beginning from the second step of complexation. Furthermore, the influence of the bulkiness of the 1‐alkyl group on separation process of Co(II) from Zn(II) for extractions with toluene and 2‐ethyl‐1‐hexanol were determined.     

Effect of Alkyl Chain Length on the Extraction of Copper(II) Complexes with 1‐Alkyl‐2‐Methylimidazoles

Abstract

By using the liquid‐liquid partition method, the formation of Cu(II) complexes with 1‐alkyl‐2‐methylimidazoles (where alkyl=isobutyl, pentyl, isopentyl, hexyl, octyl, decyl, and dodecyl) has been studied at 25°C and at fixed ionic strength of the aqueous phase (I=0.5; (HL)NO₃, KNO₃). The complexes were extracted with 2‐ethyl‐1‐hexanol, dichloromethane, trichloromethane and, in one system only, toluene. Stability constants of the complexes in aqueous solution as well as partition constants of the extractable species were determined. It has been shown that the stability constants are invariable and do not depend on the 1‐alkyl chain length. The constants were smaller than those of the previously studied Cu(II) – 1‐alkylimidazole complexes owing to the steric effect of the methyl group at position 2. The partition constants of the complexes incereased with increasing alkyl chain length. Branched 1‐alkyl substituents (isobutyl, isopentyl) suppressed both stability constants and the partition constants of the complexes.     

Cloud Point Extraction and Separation of Scandium and Yttrium (III) with Triton X‐114 in the Presence or Absence 8‐Hydroquiloline as an Added Chelate

Abstract

In this paper, the cloud point extraction and separation of scandium and yttrium (III) via use of Triton X‐114 with and without 8‐hydroquiloline (HQ) as an added chelate agent are investigated. The effects of various parameters, such as the aqueous phase pH, HQ concentration, Triton X‐114 concentration, heating temperature, and incubation time, on the cloud point extraction of scandium and yttrium (III) are studied. The results demonstrate that, there are different extraction and separation behaviors for scandium and yttrium (III) with and without HQ as an added chelate. And in contrast to solvent extraction, cloud point extraction is an excellent method to extract and separate scandium and yttrium (III).     

On the Relationships between the Hydrophilic–Lipophilic Balance and the Nanoarchitecture of Nonionic Surfactant Systems

Building links between established parameters for the characterization of surfactant systems is useful not only for the understanding of the underlying phenomena but also for the judicious formulation of products. Herein, we review comprehensively the literature data to find correlations between the hydrophilic–lipophilic balance (HLB) and the molecular packing parameter (CPP) for a variety of nonionic surfactants in water. The interfacial area per surfactant molecule, a fundamental variable to calculate CPP, follows a power law as a function of the number of ethylene oxide (EO) groups in the surfactant. The exponent ranges from 0.3 to 0.7, which may reflect changes in the conformation of the EO chain depending on the nature of the hydrophobic group; there is also apparently a transition toward a collapsed conformation of the EO chains at high surfactant concentrations. CPP is found to change linearly with HLB in the range of data studied, although the parameters of the linear fitting depend on the nature of both hydrophobic and hydrophilic moieties of the surfactant; this would also imply a linear relationship between CPP and the HLB temperature (i.e., Phase Inversion Temperature) according to the Kunieda–Shinoda equation. Analysis of the liquid crystal regions of the surfactant phase diagram at constant temperature indicates that the HLB values required for the morphological phase transitions defined by CPP increase with surfactant concentration. The present report may serve as a contribution to the programmed design of nanoarchitectures in surfactant systems.     

Diels–Alder Reaction of Cyclopentadiene and Alkyl Acrylates in the Presence of Pyrrolidinium Ionic Liquids with Various Anions

Abstract  

The conversion and stereoselectivity of transformation to endo and exo norbornene derivatives was determined in the Diels–Alder reaction of cyclopentadiene with alkyl acrylates. The reactions were carried out in the pyrrolidinium ionic liquids in the presence of metal chlorides and trifluoromethanesulfonates as the catalysts. Shorter reaction times and higher conversions of dienophile were observed in a comparison with analogous cycloadditions carried out in the presence of conventional organic solvents. A higher stereoselectivity to the endo isomer was found in the majority of cases. The ionic liquids composed of 1-butyl-1-methylpyrrolidinium cation (Pyrr_1.4) and various anions were used. The influence of ionic liquid anion and several metal chlorides and metal triflates used as the catalysts on the conversion was determined.     

Synthesis and Sulfonation of an Aluminum-Based Metal–Organic Framework with Microwave Method and Using for the Esterification of Oleic Acid

Journal of Inorganic and Organometallic Polymers and Materials - In this study, the synthesis of MIL-53(Al) (Material Institute Lavoisier, MIL) material, which is an aluminum-containing...     

Copolymerization of carbon monoxide and styrene with the Nd(III)–Cu(II) catalyst

In this article, the linear alternating copolymer of carbon monoxide and styrene was obtained using the Nd(III)–Cu(II) catalyst. It was found that the introducing order of the catalyst components can affect the catalytic activity, and the pre-prepared catalyst had higher catalytic activity than the in situ catalyst. The promoting effect of copper acetate on the catalytic activity was also investigated. The structure of the copolymer was characterized by means of IR, ¹H-NMR, ¹³C-NMR, WXRD, and EA methods. The thermal decomposition properties were checked by the way of TGA. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 8–13, 2001     

Response Surface Optimisation of an Oxalate–Phosphate–Amine Metal–Organic Framework (OPA-MOF) of Iron and Urea

Metal–organic framework (MOF) materials are well known for various application fields, such as engineering, and medical sciences. Here, the synthesis, and synthesis-optimisation of a novel oxalate-phosphate-amine MOF (OPA-MOF) for innovative agricultural applications is described, with urea as a structure-directing agent in a hydrothermal synthesis. Product properties conducive to proposed applications included yield, purity, elemental content (N, P, C), and oxalate-solubility, as important driving forces for functionality, which is based on the biomineralisation processes for the material’s decomposition in soil. A four-factors/two levels plus one (4²+1) factorial design included replicated zero-point and factors of time, temperature, urea input rate and dilution factor. 19 experimental runs results provided data for a Response Surface Method optimisation to determine factors resulting in a desired product at highest efficiency. The saddle-ridge shaped response surface highlighted system robustness for two factors (time/urea-input), and sensitivity for temperature and dilution factor. Optimal factor combinations initially appeared counterintuitive compared to expected results from factorial design outcomes, however confirmatory experiments validate model predictions. Consequently, the optimisation process was strongly justified for accurate determination of the optimal OPA-MOF synthesis conditions.     

The Influence of Alkyl Chain Length and Steric Effect on Extraction of Zinc(II) Complexes with 1‐Alkyl‐2‐Methylimidazoles

Abstract

The extraction of Zn(II) complexes with six 1‐alkyl‐2‐methylimidazoles (alkyl is from C₅H₁₁ up to C₁₂H₂₅) from nitric solution was studied as a function of pH of the aqueous phase. As the organic solvents toluene, p‐xylene and 1,2,3,4‐tetrahydronaphthalene were used. The stability constants of the complexes in the aqueous phase as well as partition constants of the extractable species were determined. It was demonstrated that both the stability constants (β_c) and the partition constants (P_c) of the complexes increased with increasing alkyl chain length. Pseudo‐tetrahedral complexes were found to dominate at the second and third complexation steps, thus increasing the stability constants and facilitating extraction of the Zn(II) complexes with 1‐alkyl‐2‐methylimidazoles.     

Microwave-Assisted Solvothermal Synthesis and Photocatalytic Activity of Bismuth(III) Based Metal–Organic Framework

This study aims to synthesize and evaluate the photocatalytic activity of bismuth terephthalate material (Bi-BDC) synthesized by solvothermal (ST) and microwave-assisted solvothermal (MW) methods. Differences in the crystal structure and crystal shape were assessed by analytical methods such as X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared (FT-IR) spectrum, X-ray photoelectron spectroscopy (XPS), N₂ adsorption/desorption, Raman spectrum, and thermal gravimetric analysis (TGA). From XRD, IR, Raman, and XPS results, the fully crystallized Bi-BDC materials were achieved regardless of the preparation router. Bi-BDC-MW exhibited spherical-like morphologies, producing between stacked lamellar, while Bi-BDC-ST method exhibited a heterogeneous structure. The TGA data indicated that Bi-BDC is thermally stable up to 300 °C, suggesting the excellent thermal stability of Bi-BDC. The surface area and pore volume of Bi-BDC-MW (18 m²/g and 85 × 10^?3 cm³/g) are higher than those of Bi-BDC-ST (16 m²/g and 52 × 10^?3 cm³/g), which is due to its well-defined lamellar microstructure and homogeneity of the crystals. Compared to Bi-BDC-ST, Bi-BDC-MW has a higher value in the content of oxygen vacancy. Moreover, the photocatalytic efficiency of Bi-BDC-MW was significantly higher than that of Bi-BDC-ST, in which 99.44% rhodamine B (RhB) is removed after 360 min of irradiation. The improved photocatalytic efficiency of Bi-BDC-MW is ascribed to the morphology, specific surface area, and oxygen defects, which exhibited the good separation of electrons and holes, as confirmed by the photoluminescence (PL). The results should open a new approach to enhancing the photocatalytic activity of bismuth terephthalate materials.

     

Incorporation of Lamotrigine Drug in the PEO–PPO–PEO Triblock Copolymer (Pluronic F127) Micelles: Effect of Hydrophilic Polymers

The hydrophobic drug Lamotrigine (LTG) shows low bioavailability after oral administration. Work has been performed to improve the aqueous solubility of LTG using the micelles of amphiphilic block copolymers. Polyethylene oxide- polypropylene oxide- polyethylene oxide triblock copolymers (PEO–PPO–PEO), known as Pluronic^®, have been the subject of current interest due to the versatile structural possibilities of varying PEO/PPO ratios. Incorporation of LTG in the aqueous micellar solutions of Pluronic^® F127 was investigated using UV–visible spectroscopy. The shapes and size of the micelles with and without LTG have been ascertained using dynamic light scattering and small angle neutron scattering experiments. Results show increase in the Pluronic^® micellar size with hard sphere radius with the incorporation of LTG. The effect of hydrophilic polymers (PEG1500 and F68) on the LTG-incorporated Pluronic^® F127 micelles was also studied and found inefficient for enhancement of the solubility of LTG. Solid forms of LTG-incorporated Pluronic^® F127 micelles with and without hydrophilic polymers, coded as LPMs, were successfully prepared through the thin-film hydration method. Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy and thermogravimetric analysis have been used to ensure the compatibility of the LTG with Pluronic^® F127 micelles in prepared LPMs. All the LPMs showed good incorporation efficiency, loading capacity and the sustained release profile of LTG. Results showed no specific improvement with the addition of hydrophilic polymers in the studied concentration range.     

Investigation of the Structure and Piezoelectricity of Poly(vinylidene fluoride–trifluroethylene) Copolymer Doped with Different Dyes

The structure and piezoelectricity of poly(vinylidene fluoride–trifluroethylene) copolymer doped with crystal violet (CV), Coumarin 2 (C2), and N,N-Dimethyl-4-nitro-4-stilbenamine (DANS) were investigated by several techniques. H- and J-aggregates are formed in the CV and C2 doped copolymer, respectively, while DANS doped copolymer showed lamella structure. Moreover, the application of pressure-induced crystalline phase in the CV doped copolymer and TSDC measurements revealed that the ferroelectric to paraelectric transition peak has taken place in the C2 and DANS doped copolymer. Kohlrausch-Williams-Watts stretched function was applied to estimate the relaxation time of the piezoelectric current. The pyroelectricity is found to be dipole-moment-dependent.     

Extraction of Parabens from Water Samples Using Cloud Point Extraction with a Non-Ionic Surfactant with β-Cyclodextrin as Modifier

A cloud point extraction process using a silicone non-ionic surfactant to extract selected parabens compounds from water samples was investigated using reversed phase high performance liquid chromatography. The cloud point extraction process, in the presence of β-cyclodextrin (β-CD) as a modifier, is a new extraction process which was optimized with five parameters, i.e. salt concentration, pH of the solution, temperature, surfactant concentration and β-CD concentration. The developed method with the β-CD modifier results in an excellent performance on detection of parabens from water samples with limits of detection in the range of 0.017–0.043 μg/L and percentage recoveries from 90.5 to 98.9 %.     

Syntheses and Characterization of New Nano-porous Soft Copper(II) Metal–organic Framework and Nano-porous Two-dimensional Manganese(II) and Zinc(II) Coordination Polymers with 4,4′-Bipyridine and 2-Sulfobenzoic Acid

Three new Cu(II), Mn(II), and Zn(II) coordination polymers with 4,4′-bipyridine (4,4′-bipy) and 2-sulfobenzoic acid (2-H₂sb) ligands, [M(4,4′-bipy)(2-sb)(H₂O)]_n, have been synthesized and characterized by IR spectroscopy and elemental analyses. The structures were determined by single-crystal X-ray crystallography. The structural studies show that the metal atoms have six-coordinate geometry with a distorted octahedral environment constructed with 4,4′-bipy and 2-sb²⁻ linkers stacked over each other to generate a two-dimension motif. Self-assembly of these compounds in the solid state is likely caused by coordination and hydrogen-bonds. While polymers containing Zn(II) and Mn(II) have analogous structures, the Cu(II)-containing nano-porous soft metal–organic framework presents a different structure.     

Correlation between Detergency of Different Oily and Solid Non-Particulate Soils and Hydrophilic–Lipophilic Deviation

This research examined the correlation between the detergency of soils with varying equivalent alkane carbon numbers (EACN) and hydrophilic–lipophilic deviation (HLD) values. The detergency of oily soils with EACN ranging from 5.2 to 16.6 was evaluated using C₁₀-4PO-SO₄Na as a primary surfactant system and a 1:1 binary mixture of C₁₀-4PO-SO₄Na and AOT as a confirmatory surfactant system (with 65/35 polyester/cotton at 25°C). These surfactant systems were characterized using HLD concepts which showed that C₁₀-4PO-SO₄Na was more hydrophilic (had a higher negative Cc value) than that of the mixed surfactant system. Detergency of the selected soils was evaluated at different salinities corresponding to HLD ranging from negative to positive values. The results showed that detergency of all soils increased with increasing salinity (starting with an HLD = −3.0 (Winsor Type I microemulsion)), reached the maximum at widely different optimum salinity (S*) but at an identical HLD value of zero (optimum Type III), and then decreased with further increasing salt levels corresponding to positive HLD values (Type II). The preferred HLD range from −3.0 to 0.0 showed detergency levels exceeding 80% removal with interfacial tension values (IFT) below 1 mN m⁻¹ for all oily soils studied. Detergency of octadecane (EACN = 18, solid at 25°C) was further conducted and demonstrated that performing detergency at HLD = −3.0 to 0.0 likewise revealed superior soil removal (over 80%) versus systems with HLD values outside this range. Thus, this work highlighted the utility of using the HLD approach in designing surfactant formulations for detergency of soils with widely varying EACN.     

Reaction of Aryl Iodides with (PCP)Pd(II)—Alkyl and Aryl Complexes: Mechanistic Aspects of Carbon—Carbon Bond Formation

The reaction of the PCP-type complex Pd(Me){2,6-(ⁱPr₂PCH₂)₂C₆H₃}( 3 ) with phenyl iodide results in the formation of Pd(I){2,6-(ⁱPr₂PCH₂)₂C₆H₃} ( 5 ), methyl iodide, toluene, and biphenyl. Formation of Pd(Ph){2,6-(ⁱPr₂PCH₂)₂C₆H₃}( 4 ) is observed during the reaction by ³¹P NMR. Reaction of 4 with aryl iodides results in the formation of 5 and Ph–Ph, Ph–Ar, and Ar–Ar, products indicative of a radical reaction. Under pseudo-first-order conditions, the rates of the reactions follow the order p-OMe > p-Me > H > p-NO₂ > m-Cl. The reaction is likely to involve electron transfer from 4 to the aryl iodide followed by fast decomposition of a postulated radical cation [Pd(Ph){2,6-(ⁱPr₂PCH₂)₂C₆H₃}]^+. ( 4 ^+.) to give a phenyl radical and [Pd{2,6-(ⁱPr₂PCH₂)₂C₆H₃}]⁺ ( 6 ⁺). Facile decomposition of the aryl iodide radical anion generates an aryl radical and I⁻. Recombination of aryl radicals gives rise to mixed biaryls, and 6 ⁺ combines with I⁻ to give 5 .     

Application of the Hydrophilic–Lipophilic Deviation Concept to Surfactant Characterization and Surfactant Selection for Enhanced Oil Recovery

The hydrophilic–lipophilic deviation (HLD) concept has been demonstrated to be useful in determining characteristic curvature (Cc) of a surfactant. Cc is a surfactant parameter that reflects the hydrophobicity/hydrophilicity or the tendency of the surfactant to form microemulsions in an oil–water system. In order for the Cc value to be calculated, the formation of the optimum Winsor III microemulsion of oil and water systems under specific salinity and temperature conditions is required. Surfactant Cc values have been widely used to quantitatively screen and select a suitable surfactant in formulations for different application areas, especially enhanced oil recovery (EOR). The HLD concept is an effective tool for designing new surfactant molecules to meet the target Cc value for a specific formulation condition. The HLD equation indicates the dependence of a microemulsion system on the changes of various system parameters. This article demonstrates how the HLD equation can be derived in different ways depending on the characteristics of the surfactant to identify the proper experimental approach so that the Cc values of different types of surfactants can be determined. Three types of surfactants were studied, including nonionic alcohol ethoxylates, anionic alkyl propoxy ethoxy sulfates, and carboxylates. The application of the HLD concept to surfactant selection for EOR application was also demonstrated.