Mixed Solvent System Research Articles

Supercritical Technology-Based Date Sugar Powder Production: Process Modeling and Simulation

Date palm fruits (Phoenix dactylifera) contain high levels of fructose and glucose sugars. These natural sugar forms are healthy, nutritional and easily assimilate into human metabolism. The successful production of soluble date sugar powder from nutritious date fruits would result in a new food product that could replace the commercial refined sugar. In this work, a novel process technology based on the supercritical extraction of sugar components from date pulp was modeled and simulated using Aspen Plus software. The process model consisted of three main steps that were individually simulated for their optimal working conditions as follows: (a) freeze-drying of the date pulp at −42 °C and 0.0001 bar; (b) supercritical extraction of the sugar components using a 6.77 wt.% water mixed CO2 solvent system at a pressure of 308 bar, temperature of 65 °C, and CO2 flow rate of 31,000 kg/h; and (c) spray-drying of the extract using 40 wt.% Gum Arabic as the carrier agent and air as drying medium at 150 °C. The overall production yield of the process showed an extraction efficiency of 99.1% for the recovery of total reducing sugars from the date fruit. The solubility of the as-produced date sugar powder was improved by the process selectivity, elimination of insoluble fiber contents, and the addition of Gum Arabic. The solubility of the final date sugar product was estimated as 0.89 g/g water.

A Chromo-Fluorogenic Naphthoquinolinedione-Based Probe for Dual Detection of Cu2+ and Its Use for Various Water Samples.

The presence of an abnormal amount of Cu2+ in the human body causes various health issues. In the current study, we synthesized a new naphthoquinolinedione-based probe (probe 1) to monitor Cu2+ in different water systems, such as tap water, lakes, and drain water. Two triazole units were introduced into the probe via a click reaction to increase the binding affinity to a metal ion. In day-light, probe 1 dissolved in a mixed solvent system (HEPES: EtOH = 1:4) showed a vivid color change from light greenish-yellow to pink in the presence of only Cu2+ among various metal ions. In addition, the green luminescence and fluorescence emission of the probe were effectively bleached out immediately after Cu2+ addition. The limit of detection (LOD) of the probe was 0.5 µM when a ratio-metric method was used for metal ion detection. The fluorescence titration data of the probe with Cu2+ showed a calculated LOD of 41.5 pM. Hence, probe 1 possesses the following dual response toward Cu2+ detection: color change and fluorescence quenching. Probe 1 was also useful for detecting Cu2+ spiked in tap/lake water as well as the cytoplasm of live HeLa cells. The current system was investigated using ultraviolet-visible and fluorescence spectroscopy as well as density functional theory calculations (DFT).

Novel synthesis of high-surface-area alumina using toluene-dimethylformamide as synthetic media

Alumina support with high surface area was synthesized with a simple mixed solvent system of toluene-dimethylformamide (DMF) as synthetic media and aluminum tri-sec-butoxide/aluminum isopropoxide as aluminum precursors at an optimal Toluene/DMF volume ratio of 0.4. The specific surface area (SBET) of the alumina support prepared was about 1000 m2/g after vacuum drying at 200 °C for 4 h. It was found that these alumina supports were converted into α-Al2O3 at 1100–1200 °C with surface areas ranging from 100 to 160 m2/g. Two consecutive changes in alumina texture were observed during the alumina phase transformations, 1) Small mesoporous alumina with a pore size < 8 nm at the calcination temperature of 200 °C (SBET =1000 m2/g) can be obtained, 2) Large mesoporous alumina support with uniform pore sizes of 10–20 nm at over 1000 °C can be formed using the same fresh starting material. Based on the results, the simultaneous hydrolysis and condensation of the alkoxides and careful slow drying of the alumina in the toluene-DMF system were largely contributed to the preparation of high surface areas of alumina by forming a uniform film without any crack. The supports were characterized using different methods, including Brunauer-Emmett-Teller (BET), and X-ray powder diffraction (XRD), and scanning electron microscope (SEM). Furthermore, the performance of prepared supports was investigated in the chemical looping combustion (CLC) process using CuO-based oxygen carrier (OC).

Impacts of Solvent and Alkyl Chain Length on the Lifetime of Singlet Cyclopentane-1,3-diyl Diradicaloids with π-Single Bonding.

The singlet 2,2-dialkoxycyclopentane-1,3-diyl diradicaloids are not only the important key intermediates in the process of bond homolysis but are also attracting attention as π-single bonding compounds. In the present study, the effects of solvent viscosity η (0.24-125.4 mPa s) and polarity π* (-0.11 to 1.00 kcal mol-1) on the reactivity of localized singlet diradicaloids were thoroughly investigated using 18 different solvents including binary mixed solvent systems containing ionic liquids. In low-η solvents (η < 1 mPa s), the lifetimes of singlet diradicaloids, which are determined by the rate constant for the isomerization of π-single-bonded singlet diradicaloids to the σ-bonded isomer, were substantially dependent on π*. Slower isomerization was observed in more polar solvents. In high-η solvents (η > 2 mPa s), the rate of isomerization was largely influenced by η in addition to π*. Slower isomerization was observed in more viscous solvents. Experimental results demonstrated the crucial roles of both solvent polarity and viscosity in the reactivity of singlet diradicaloids and thus clarified the characters of singlet diradicaloids and molecular motions during the chemical transformation. The dynamic solvent effect was further proved by a long alkyl chain introduced at a remote position of the reaction site.

Influence of mixed-solvent system and reaction temperature on in situ, surfactant-free synthesis of P3HT:SnS nanocomposites

Influence of mixed-solvent system and reaction temperature on in situ, surfactant-free synthesis of P3HT:SnS nanocomposites

Privileged Scaffold Chalcone: Synthesis, Characterization and Its Molecular Interactions with Addition of 3-phenyl-1- (3,4-dibromophenyl) prop-2-en-1-one in Mixed Solvents at Various Temperatures

3-phenyl-1- (3,4-dibromophenyl) prop-2-en-1-one have been synthesized and characterized by M.P., Infrared spectroscopy, Thin Layer Chromatography, and H1 NMR and GCMS data. The ultrasonic velocity and refractive indices of mixed solvents 0-100% (by wt.) of 3-phenyl-1- (3,4-dibromophenyl) prop-2-en-1-one have been measured at three different temperatures 298, 303, and 308K. The experimental data obtained was used to calculate various parameters such as Molar volume (Vm), Free volume (Vf) , Acoustical impedance (Z), intermolecular free path length(Lf), adiabatic compressibility(), Rao’s molar sound velocity (Rm), Relative association (Ra) Molar refraction (Rm), Specific refraction (r) and Polarisability constant(a). These parameters are interpreted in terms of solute- solute and solute- solvent interaction and its effect on mixed solvent systems..

Agricultural waste of Ipomoea batatas leaves as a source of natural dye for green coloration and bio-functional finishing for textile fabrics

Agricultural wastes are precious biomass resources that have been misplaced. This work aims to verify the usability of Ipomoea batatas leaves for simultaneous dyeing and functional finishing (anti-bacterial and anti-ultraviolet) of textile fabrics without the use of inorganic salts and metal mordants for the cleaner production of environmentally friendly value-added products. The optimal extraction conditions for natural dye were investigated by the single-factor analysis as ethanol/water (6:4) mixed solvent system with a material-liquid ratio of 1:10, a temperature of 90 ℃, a time of 1.5 h, and a pH value of 7. The adsorption kinetics study showed that the adsorption behavior of the natural dye on silk fabric was more consistent with the pseudo-second-order kinetic model and the Langmuir model. Meanwhile, the natural dye extracted from Ipomoea batatas leaves could be used for simultaneous salt-free dyeing and functional finishing of silk fabric and other fiber types with good color fastness, antibacterial properties and UV resistance with some durability, and the color strength in the order of wool, nylon, cotton, silk and polyester fabric. The outcome of this study can provide a possibility for the application of agricultural wastes in textile eco-dyeing and finishing, as well as the value-added management of green wastes.

Electrochemical Investigation of the Oxidation of Thiosulfate by 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane and Its Anion Radical

AbstractThe oxidation of thiosulfate has been of interest for more than a century, including the famous oscillating iodine clock reaction. From a thermodynamic perspective, calculations based on the reversible potentials reveal that both neutral TCNQF40 (2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane) or its radical anion (TCNQF41−) can oxidize thiosulfate to tetrathionate to form TCNQF42−. The reaction of S2O32− with TCNQF40 in a 2:1 or greater concentration ratio occurs in a step‐wise fashion to initially (and rapidly) form S4O62− and TCNQF41− (reaction 1), followed by a slow step involving the oxidation of residual S2O32− by TCNQF41− to give more S4O62− and TCNQF42− (reaction 2). Thus, this reaction occurs in two, temporally well‐resolved, steps with dramatically different kinetics. If S2O32− and TCNQF41− are mixed in a 1 : 1 ratio, then S4O62− and TCNQF42− are formed quantitatively on the same (hours) timescale, as for the second (slow) step described above. There is no evidence of further oxidation of S4O62− to SO42−. A slight increase in the rate of reaction 2 was observed in the presence of Bu4NPF6 and attributed to ion‐pairing effects. Interestingly, during voltammetric experiments, if the Pt counter electrode is not separated from the reaction solution via a salt bridge, reaction 2 is catalyzed. The rates of reaction 2 have been studied over a wide range of conditions. Intriguingly, the mechanisms are dependent on whether S2O32− or TCNQF41− (much faster) are in excess. With S2O32− in excess, the rate of reaction is first‐order in both S2O32− and TCNQF41−. With TCNQF41− in excess, the reaction is more complicated with indications of Li+ catalysis through electrostatic shielding of the TCNQF41− and/or S2O32− reactants. The large difference in rate of reaction of TCNQF40/S2O32− (rapid) compared with TCNQF41−/S2O32− (sluggish) is in part attributable to the much larger driving force in the former case. All experimental studies were undertaken in the mixed solvent system, acetonitrile (MeCN) containing 5 % water, v/v (95 % MeCN : 5 % water) where all the reactants and products are soluble and stable. Voltammetric analysis using steady‐state (microdisc) or transient cyclic voltammetry (macrodisc) with electrolyte (Bu4NPF6) and UV‐visible spectrophotometry with or without electrolyte were used to monitor the time dependence and establish the identity of the products.

Whither Second-Sphere Coordination?

Whither Second-Sphere Coordination?

Approach toward Iron(II) Coordination Polymers Based on Chain Motifs with Thiolate or Mixed Thiolate/Carboxylate Bridges: Structures and Magnetic Properties.

The search for iron-sulfur-based coordination polymers (CPs) has become an attractive field in recent years. Here we demonstrate how it is possible to synthesize new iron-sulfur-based CPs by solvothermal reactions of [CpFe(CO)2]2 (Cp = cyclopentadienyl) with two positional isomeric ligands 6-mercaptonicotinic acid (6-H2mna) and 2-mercaptoisonicotinic acid (2-H2mina) in different mixed-solvent systems. The reactions afforded, in moderate yields, a variety of desired CPs, namely, [Fe(6-Hmna)2] (1), [Fe3(6-Hmna)2(6-mna)2] (2), [Fe2(6-mna)2]·H2O (3), and [Fe(2 mina)(H2O)] (4 and 5). The structures of these compounds have been characterized by single-crystal X-ray diffraction, which reveals that they all contain 1D chain motifs of iron held together in different ways by thiolate or mixed thiolate/carboxylate bridges. These chains are further connected through the ligand backbones to form 3D networks of 1-3 and 5 and a 2D sheet of 4. Moreover, magnetic investigations indicate that both 1 and 4 display canted antiferromagnetic behavior with weak ferromagnetism, while 2 and 5 possess short-range antiferromagnetic order at ∼20 K. CP 3 exhibits paramagnetic behavior down to 2 K with strong spin frustration.

IONIC LIQUIDS: RECENT JOURNEY THROUGH CHROMATOGRAPHIC SEPARATION

Ionic liquids (ILs), despite some of their crucial disadvantages, have been established to be the apt and relevant replacement of the volatile organic compounds (VOCs) in the industrial and academic sectors as solvents. Recent investigations on thriving multifaceted applications of ionic liquids have unleashed that they are really among beneficial “environmentally-benign” solvents as far as their impact on the ecosystem is concerned. This caused them to be an exciting and lucrative domain to explore in a wider fashion and many of the leading research groups are involved in the manifestation of their inherent undisclosed legacy. While exploring the efficacy of ILs, it was found that ILs or IL-based mixed solvent systems were very good alternative of conventional solvents and could act as mobile/stationary phases or additives in gas chromatography (GC), multidimensional gas chromatography (MDGC), inverse gas chromatography (IGC), high performance liquid chromatography (HPLC) and capillary electrophoresis (CE) very efficiently. Their (IL’s) efficacy in improvising and synchronizing the mode and nature of the chromatographic separation is well-established, undoubtedly commendable and unique in many ways. In this review we have put our concentration on the recent, beneficial and some less-explored aspects of the implementation of ILs in the above said chromatographic separation domain.

Further Investigation of Solvent Synergists for Improved Performance of Poly(N-vinylcaprolactam)-Based Kinetic Hydrate Inhibitors

Poly(N-vinylcaprolactam) (PVCap) and related copolymers have been used as kinetic hydrate inhibitors (KHIs) to combat gas hydrate formation in oil and gas field production flow lines. It is known that the addition of certain solvents to the KHI polymer can enhance its ability to hinder gas hydrate formation. In an earlier study, a wide range of alcohols, glycol ethers, and ketones were investigated as synergetic solvents with PVCap. In that study, an outstanding synergetic effect was achieved by 4-methyl-1-pentanol (iHexOl). This report builds on that study by investigating iHexOl in more detail as well as some newly synthesized solvents predicted by the first study to have good synergism. Both slow constant cooling (SCC) and isothermal KHI experiments were conducted in high-pressure steel rocking cells using a structure II-forming natural gas mixture. The KHI polymer concentration, solvent concentration, and mixed solvent systems were investigated. The solvent synergist water solubility, also in brines, and partitioning to the liquid hydrocarbon phase are shown to be important factors to consider for optimizing KHI performance. Further, it was observed that the optimal molecular weight distribution for the KHI polymer when used with a solvent synergist is not the same as the optimum distribution when using the polymer alone.

Biphenyl-Induced Superhelix in l -Phenylalanine-Based Supramolecular Self-Assembly with Dynamic Morphology Transitions

Biphenyl-Induced Superhelix in <scp>l</scp> -Phenylalanine-Based Supramolecular Self-Assembly with Dynamic Morphology Transitions

A Solvent-Polarity-Induced Interface Self-Assembly Strategy towards Mesoporous Triazine-Based Carbon Materials.

Triazine-based materials with porous structure have recently received numerous attentions as a fascinating new class because of their superior potential for various applications. However, it is still a formidable challenge to obtain triazine-based materials with precise adjustable meso-scaled pore sizes and controllable pore structures by reported synthesis approaches. Herein, we develop a solvent polarity induced interface self-assembly strategy to construct mesoporous triazine-based carbon materials. In this method, we employ a mixed solvent system within a suitable range of polarity (0.223≤Lippert-Mataga parameter (Δf) ≤0.295) to induce valid self-assembly of skeleton precursor and surfactant. The as-prepared mesoporous triazine-based carbon materials possess uniform tunable pore sizes (8.2-14.0 nm), high surface areas and ultrahigh nitrogen content (up to 18 %). Owing to these intriguing advantages, the fabricated mesoporous triazine-based carbon materials as functionalized porous solid absorbents exhibit predominant CO2 adsorption performance and exceptional selectivity for the capture of CO2 over N2 .

A Solvent‐Polarity‐Induced Interface Self‐Assembly Strategy towards Mesoporous Triazine‐Based Carbon Materials

AbstractTriazine‐based materials with porous structure have recently received numerous attentions as a fascinating new class because of their superior potential for various applications. However, it is still a formidable challenge to obtain triazine‐based materials with precise adjustable meso‐scaled pore sizes and controllable pore structures by reported synthesis approaches. Herein, we develop a solvent polarity induced interface self‐assembly strategy to construct mesoporous triazine‐based carbon materials. In this method, we employ a mixed solvent system within a suitable range of polarity (0.223≤Lippert–Mataga parameter (Δf) ≤0.295) to induce valid self‐assembly of skeleton precursor and surfactant. The as‐prepared mesoporous triazine‐based carbon materials possess uniform tunable pore sizes (8.2–14.0 nm), high surface areas and ultrahigh nitrogen content (up to 18 %). Owing to these intriguing advantages, the fabricated mesoporous triazine‐based carbon materials as functionalized porous solid absorbents exhibit predominant CO2 adsorption performance and exceptional selectivity for the capture of CO2 over N2.

Studies on molecular interactions of l-histidine/l-serine in aqueous diphenhydramine hydrochloride solutions at various temperatures: Volumetric, ultrasonic and viscometric approach

Thermophysical properties for varying concentrations of essential (L-histidine) and non-essential (L-serine) amino acids in water and (0.05–0.15) mol kg−1 mixed aqueous diphenhydramine hydrochloride solvent system has been deliberated at different temperatures ranging (293.15−318.15) K and ambient pressure (101.3 kPa). The experimentally obtained data has been utilized to compute different volumetric, compressibility and rheological parameters such as apparent molar volume (Vϕ), partial molar volume (V0ф), partial molar expansibility (E0ϕ), apparent molar isentropic compression (Kϕ,s), partial molar isentropic compression (K0ϕ,s), hydration number (nH), transfer parameters, viscosity coefficients etc. The structure breaking ability of the solute molecules has been comprehended using Hepler′s constant (temperature derivative of partial molar expansibility at constant pressure) and dB/dT (temperature derivative of viscosity B-coefficient) values. Further, by using the co-sphere overlap model various sorts of solute-drug interactions prevailing in the systems have been discussed.

Measurement and Correlation of the Solubility of Gestodene in 11 Pure and Binary Mixed Solvent Systems at Temperatures from 283.15 to 323.15 K

Measurement and Correlation of the Solubility of Gestodene in 11 Pure and Binary Mixed Solvent Systems at Temperatures from 283.15 to 323.15 K

Polymorphism in acetyl-CoA synthase mimic complex [NiN2S2-(W(CO)5)2

One trimetallic compound (μ-η2-Ni-1)[W(CO)5]2 (NiW2) was prepared by reaction of the Ni(II) dithiolate metalloligand, [Ni-bme-dach] where bme-dach = bis-(mercaptoethyl)diazacycloheptane, with W(CO)6 in CH2Cl2 under a certain treatment. Two solvent-free polymorphs of NiW2 (I and II) and two solvates NiW2(CH2Cl2) (III) and NiW2(C6H6) (IV) were obtained by crystallization in various solvent conditions. Conformations I and II exhibit concomitant polymorphisms in CH2Cl2 solvent system. However, conformations of III and IV were obtained in mixed solvent system of CH2Cl2 with CHCl3 and benzene, respectively. For morph II*, it was obtained by heating treatment of conformation II at 160 °C for 20 min. Two low-valent metallic W0(CO)5 groups in I to IV were bridged by Ni-1 in the transoid modes, giving W-W distances of 5.576(17) Å to 6.024(3) Å.

Chitosan membranes from acetic acid and imidazolium ionic liquids: Effect of imidazolium structure on membrane properties

Mixed solvent systems of an acetic acid aqueous solution with different imidazolium ionic liquids were developed for successful chitosan dissolution at room temperature, then chitosan membranes were prepared using casting method. 1-butyl-3-methyl-imidazolium acetate ([Bmim]Ac), 1-ethyl-3-methyl-imidazolium chloride ([Emim]Cl), and 1-methyl-3-(3-sulfopropyl) imidazolium zwitterion (mPSO3) were used for chitosan dissolution. Chitosan membranes were characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance characterization (1HNMR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), water contact angle, swelling degree, and tensile strength. The effect of imidazolium ionic liquid addition upon the physicochemical properties of chitosan membrane was clarified. The results indicated that chitosan could not dissolve in common imidazolium-based ionic liquid aqueous solutions, while the imidazolium ionic liquid addition positively participated in chitosan dissolution of acetic acid aqueous solutions. The results also showed that imidazolium ionic liquids reduced the crystallinity of chitosan membranes, while improved the thermal stability and strength tensile of membranes. Moreover, imidazolium ionic liquids showed different effects on crystallinity reduction, contact angles, and swelling degree. It is possible of tuning the physicochemical properties of chitosan membranes by adding different imidazolium ionic liquids during aqueous acetic acid dissolution. The information obtained will shed light on the optimization of novel solvent systems for fast and rapid chitosan dissolution.

Spectrophotometric study of the sodium dodecyl sulfate in the presence of methylene blue in the methanol–water mixed solvent system

The methylene blue (MB) dye is very sensitive to changes in the polarity of its surroundings. The interaction of MB with sodium dodecyl sulfate (SDS) was studied spectrophotometrically in 0.1, 0.2, 0.3 and 0.4 vol fractions of methanol in an aqueous medium. The dielectric constant value decreases with the addition of methanol in the water and hence there is the lower stabilization of the lowest unoccupied molecular orbital which results in the hypsochromic shift in the monomeric form of methylene blue. In a 0.1 vol fraction of methanol, the peaks are seen at 665 and 612 nm, which are monomeric and dimeric MB peaks, respectively. The dimerization of MB is reduced with the increasing volume fraction of methanol in the solvent and ceases at/above 0.3 vol fraction of methanol. In the 0.4 vol fraction of methanol, the turbidity appears with the addition of SDS and there were no significant changes in the absorbance. In the presence of methanol, MB prefers to stay with the sulfate groups of SDS at the peripheral regions of the premicelle and micelle. At very low surfactant concentrations, far below their critical micelle concentration (CMC), the formation of MB-MB dimers and/or MB-SDS ion pairs or clusters occurs, and a corresponding shift in absorption and decrease in absorbance is observed. On increasing the concentration of SDS, micellization occurs, which disrupts the MB-MB dimers and MB-SDS ion pairs are incorporated with the micelles. On further addition of SDS, lone MB monomers become associated with these micelles and the absorbance increases slightly higher than those of the original dye in the solvent. This is the case of dye solubilization where monomers are completely incorporated or bounded by micelles. The CMC of SDS decreases in the presence of dye suggesting the strong interaction between the oppositely charged dye-surfactant ion pairs. The value of binding constant and partition coefficient decreased with the increasing volume fraction of methanol. The negative value of ΔGb indicates that the interaction between SDS and MB is spontaneous but the negative values of ΔGb decreased with the increasing volume fraction of methanol.