Effect Of Solvent Properties Research Articles

Effect of Solvent Properties and Composition on the Solubility of Ganciclovir Form I

Characterization of physical properties of polymorphs in pharmaceuticals is a very important aspect of drug development and manufacturing. This work is to improve the solubility and calculate dissolution thermodynamics of ganciclovir form I. An isothermal saturation method was applied to measure the solubility values of ganciclovir form I in some pure and mixed solvents at temperatures ranging from 278.15 to 318.15 K at atmospheric pressure. The solubility obtained a maximum value in pure 1-butanol and a minimum data in neat toluene. The obtained solubility data of ganciclovir form I in pure solvents were correlated with the modified Apelblat equation, the λh equation, and the NRTL model. Meanwhile, the Jouyban–Acree model was applied to simulate ganciclovir form I solubility in binary mixture compositions at various temperatures. The maximum value of the relative average deviation (RAD) was 3.04%, which indicates the experimental data was well consistent with the calculated ones. Apparent thermodynamic a...

Electrospun polyurethane microporous membranes for waterproof and breathable application: the effects of solvent properties on membrane performance

Electrospun polyurethane (PU) based nanofibrous mats were fabricated from the solutions prepared with different volume ratios of N,N-dimethylformamide (DMF), methanol (MeOH), and dichloromethane (DCM). The membrane structures such as the nanofiber diameter, the pore size distribution, and the porosity were investigated in detail. And the morphological, mechanical, waterproof, and breathable properties of the membranes were used to estimate the characteristics of the membranes. Various solutions were compared to obtain porous nanofibrous membranes without beads or curls, which revealed that morphologies of PU fibrous membranes could be finely regulated by tuning the solvent volume ratios and the solution concentrations. The results showed that the nanofibrous membranes with the DMF/DCM solvents exhibited the high fiber diameter (500–700 nm) and the wide pore size distribution (0.6–1.2 µm). Besides, the water contact angle (WCA) of the PU nanofibrous film using the 100% DMF was 133°, but it could not persist for a long time. And the resultant membranes presented high hydrostatic pressure to 2.1 kPa, modest water vapor transmission rate of 10.1 kg/m2/day, as well as robust mechanical properties with tensile strength of 6.6 MPa, which are desirable in many important applications including protective clothing.

Effects of Solvent Properties on the Anion Binding of Neutral Water-Soluble Bis(cyclopeptides) in Water and Aqueous Solvent Mixtures.

In this study, the anion-binding bis(cyclopeptide) 2 is introduced, which dissolves freely in water, affording up to 10 mM concentrations, thanks to triethylene glycol-derived substituents in the cyclopeptide subunits and the linker connecting them. Binding studies provided evidence that the anion affinity previously demonstrated for less-soluble analogs of this compound is retained under highly competitive aqueous conditions. The highest affinity in water was observed for iodide, closely followed by sulfate anions, whereas binding of soft and weakly coordinating anions could not be observed. The anion selectivity of 2 thus differs from that of other recently described receptors, which also do not require electrostatic or coordinative interactions for anion binding in water but typically fail to bind strongly coordinating sulfate anions. The ability of 2 to overcome sulfate hydration is attributed to the special mode of binding, combining direct N–H···A– interactions with the release of water molecules from the receptor cavity. The characterization of the anion binding of 2 and a related bis(cyclopeptide) in a variety of different solvents and aqueous solvent mixtures furthermore allowed the correlation of the binding properties with solvent parameters. These analyses provided qualitative and even quantitative insights into the solvent properties and solvation phenomena that mainly affect anion complexation.

Effect of temperature and solvent properties on the process of complex formation between crown ether 15C5 and Na+ in the (propan-1-ol + water) mixture at temperatures from T = 293.15 K to T = 308.15 K

Thermodynamic functions of complex formation of 15-crown-5 ether (15C5) with sodium cation (Na+) in the mixtures of propan-1-ol (PrOH) with water (W) at different temperatures have been calculated. To obtain this function two experimental methods have been used. The equilibrium constants of complex formation (15C5/Na+) have been determined by conductivity measurements and the enthalpic effect of complex formation has been measured by the calorimetric method and has been also calculated using van’t Hoff’s equation. The complexes are enthalpy stabilized but entropy destabilized. Effect of solvent properties on the process of complex 15C5/Na+ formation in PrOH+W mixtures has been discussed. The obtained results were compared with analogous data in the mixtures of water with methanol or ethanol and discussed.

Gaining Control over the Mechanism of Oxygen Reduction in Organic Electrolytes: The Effect of Solvent Properties

In the present study, we employ differential electrochemical mass spectroscopy (DEMS) to investigate how additives to lithium containing organic electrolytes influence the mechanism of electrochemical oxygen reduction reaction. We find that some additives favor the formation of superoxide over the formation of lithium peroxide. We have tried to relate the influence of the additive on superoxide formation to properties of the pure solvent: Additives with a large donor number do not exert any influence. Although all additives with a large acceptor number facilitate superoxide formation, we have ascribed the effect to the polarity of the additive. We discuss in the present paper how the polarity of the additive increases solvent rearrangement energies. Following the Marcus–Hush theory this introduces an activation barrier for the second electron transfer. Therefore, electrochemical oxygen reduction stops at the superoxide stage, and larger overpotentials are required to facilitate the second electron transfe...

Insights into the effects of solvent properties in graphene based electric double-layer capacitors with organic electrolytes

Abstract Organic electrolytes are widely used in electric double-layer capacitors (EDLCs). In this work, the microstructure of planar graphene-based EDLCs with different organic solvents are investigated with molecular dynamics simulations. Results show that an increase of solvent polarity could weaken the accumulation of counter-ions nearby the electrode surface, due to the screen of electrode charges and relatively lower ionic desolvation. It thus suggests that solvents with low polarity could be preferable to yield high EDL capacitance. Meanwhile, the significant effects of the size and structure of solvent molecules are reflected by non-electrostatic molecule-electrode interactions, further influencing the adsorption of solvent molecules on electrode surface. Compared with dimethyl carbonate, γ-butyrolactone, and propylene carbonate, acetonitrile with relatively small-size and linear structure owns weak non-electrostatic interactions, which favors the easy re-orientation of solvent molecules. Moreover, the shift of solvent orientation in surface layer, from parallel orientation to perpendicular orientation relative to the electrode surface, deciphers the solvent twin-peak behavior near negative electrode. The as-obtained insights into the roles of solvent properties on the interplays among particles and electrodes elucidate the solvent influences on the microstructure and capacitive behavior of EDLCs using organic electrolytes.

Response surface evaluation of microwave-assisted extraction conditions for Lycium barbarum bioactive compounds

Abstract The effects of microwave-assisted extraction (MAE) on the qualitative and quantitative composition of extracted bioactive phytochemicals are strongly dependent on specific operational conditions. The impact of temperature, extraction time, and solvent dielectric properties on the MAE of antioxidant compounds from goji berry is hereby reported and discussed. Results were evaluated in terms of antioxidant capacity (ascertained by ABTS and ORAC assays), complemented with quantification of total phenolics content (TPC), and characterization of extracts through HPLC. Furthermore, the effect of storage temperature was also studied. Results revealed that temperature and solvent properties exert a significant effect on TPC and ORAC assays, whereas irradiation time plays a key role in the preparation of extracts to be evaluated through ABTS. The effect of solvent properties is tentatively explained considering the dielectric properties of methanol and water, whereas the observed effect of temperature could be explained by its influence on the solubility of phenolic compounds. Industrial Relevance A careful selection of operational conditions during MAE, designed for a specific antioxidant assay, allows an increase in the bioactivity of the resultant extracts, which may become important in terms of industrial applications.

Effect of Solvent Properties on the Swelling Assisted with Protrusion of PS@TiO<sub>2</sub>

swelling; core-shell microspheres; Janus; solubility parameter; polar fraction Abstract. Janus particles have particular properties and potential application for their asymmetry dual-faced structure. In this report, we study the effect of the solubility parameter and the polar fraction of solvent on the swelling assisted with protrusion of polystyrene @ titanium dioxide (PS@TiO2) core-shell microspheres. The resultant titanium dioxide/polystyrene (TiO2/PS) Janus particles were characterized by scanning electron microscope. Results indicated that solvent with the solubility parameter of about 9.3 (cal/cm3)1/2 and with low polarity such as dimethylbenzene, carbon disulfide and methyl methacrylate exhibited the preferable swelling efficiency. Janus particles have particular properties and potential application for their asymmetry dual-faced structure. In this report, we study the effect of the solubility parameter and the polar fraction of solvent on the swelling assisted with protrusion of polystyrene @ titanium dioxide (PS@TiO2) core-shell microspheres. The resultant titanium dioxide/polystyrene (TiO2/PS) Janus particles were characterized by scanning electron microscope. Results indicated that solvent with the solubility parameter of about 9.3 (cal/cm3)1/2 and with low polarity such as dimethylbenzene, carbon disulfide and methyl methacrylate exhibited the preferable swelling efficiency.

Effect of solvent properties on reaction of isocyanates with mercaptans

Generalization of data on the reaction rate of catalyzed process between mercaptans and phenyl isocyanate in various media led to the conclusion that the reaction rate increased due to the specific, especially nucleophilic, solvation. The primary reaction stage is the formation of a complex between the acidic mercaptan and a base, a catalyst (triethylamine) or basic solvent.

Effects of solvent properties on cationic dyeing process of acrylic yarn

Cationic dye is a special dye for acrylics, but it is very difficult in dyeing through the core. In practice, the price of a special leveling agent for acrylic fiber is high, and uniform staining is poor. By mixing a number of organic solvents in the dye bath, we can improve the structure of fibers and their deep-dyeing. We used n-propanol, isopropanol and benzyl alcohol as organic solvents, by adjusting the pH value and the appropriate temperature, and with special depth and leveling agent for dyeing soaping fastness contrast, to find economically viable process conditions.

Reducing the Cost of CO2 Capture from Flue Gases Using Aqueous Chemical Absorption

Chemical absorption is widely regarded as the most promising technology for CO2 capture from large industrial sources in the short term. The cost of CO2 capture from postcombustion power plants using monoethanolamine (MEA), the benchmark for chemical absorption, is currently over US$70 per metric ton of CO2 avoided. This high cost is considered as the major obstacle to current large-scale implementation of carbon capture and storage (CCS). Thus, there has been significant focus on the development of new solvents with the aim to reduce costs. This paper provides insights into the impact of solvent properties on the cost of capture to assist in the development of new solvents based on a 500 MW supercritical black coal power plant as the emission source. The effect of solvent properties, specifically solvent loading, heat of reaction, solvent loss, and solvent concentration is examined. The effect of improvements in process design, specifically high pressure stripper operation, advanced structured packing, u...

Effects of alcohol solvents on anatase TiO2 nanocrystals prepared by microwave-assisted solvothermal method

The effects of solvents on the anatase crystallite size prepared by sol–gel microwave-assisted solvothermal method were investigated in this study. Eight different alcohol solvents classified into two groups, i.e. primary and secondary/ternary alcohols, were used as reaction media and the effects of solvent properties, such as dielectric constant, boiling point, and internal pressure during the solvothermal process, on the crystallite size and shape were analyzed. According to the experimental results, selecting the solvent type allowed not only the alteration of the crystallite size but also the crystallite shape without the need of any additives. The boiling point of solvent was determined as the major factor influencing the crystallite size. Among the solvents with similar boiling points, the solvent with a higher carbon number produced the smaller crystallite size because of steric hindrance effect. In addition, the carboxyl groups dissociated from the alcohol solvent can play a role as a structural capping agent to retard the anatase crystal growth along the [001] direction and led to a rectangular crystallite shape with preferred development in {001} facets. On the other hand, the alcoholysis reaction was found easily occurred between the primary alcohol and isopropoxide that effectively limited the hydrolysis and condensation processes but also suppressed the structural capping effect. Therefore, the anatase crystals prepared in the primary alcohols became exceptionally small and showed spherical shape. Finally, the anatase crystals prepared using isopropanol demonstrated the highest photocatalytic activity due to its evident preferred crystallization in the {001} facets.

Effects of Solvent Properties on the Spectroscopy and Dynamics of Alkoxy-Substituted PPV Oligomer Aggregates

Conjugated systems are frequently studied in their nanoaggregate form to probe the effects of solvent and of film formation on their spectral and dynamical properties. This article focuses on the emission spectra and dynamics of nanoaggregates of alkoxy-substituted PPV oligomers with the goal of interpreting the vibronic emission envelopes observed in these systems (J. Phys. Chem. C2009, 113, 18851-18862). The aggregates are formed by adding a nonsolvent such as methanol (MeOH) or water to a solution of the oligomers in a good solvent such as methyl tetrahydrofuran (MeTHF) or tetrahydrofuran (THF). The emission spectra of aggregates formed using either of these combinations exhibit a vibronic pattern in which the ratio of the intensity of highest-energy band to that of the lower energy peaks depends strongly on the ratio of good to poor solvent. In aggregates formed from MeTHF:MeOH, this was shown to be due to the presence of both aggregate-like and monomer-like emitters forming a "core" and surrounding "shell"-like structure, respectively, within a single aggregate (J. Phys. Chem. C2011, 115, 15607-15616). In support of this model, the monomer-like emission is shown here to be significantly decreased by changing the solvent pair to the more polar THF:water. This suggests that nanoaggregates formed in THF:water contain a much smaller proportion of monomer-like chains than those formed in MeTHF/MeOH, as would be expected from using a more highly polar nonsolvent. Results from bulk steady-state and time-resolved emission measurements as well as fluorescence lifetime imaging microscopy (FLIM) of the aggregates are shown to be consistent with this interpretation.

Aspen Plus Simulation of CO2 Removal from Coal and Gas Fired Power Plants

This paper presents a description of the CO2 removal process of 500MW coal and gas fired power plants. The parameters and other operating conditions for Aspen Plus rate based model were selected to achieve 85% of CO2 removal. The effects of absorber pressure and packing height on re-boiler duty are studied. Re-boiler duty is decreasing with the increase of packing height and absorber pressure. The effect of solvent properties on CO2 removal efficiency is also analyzed. The removal efficiency increases as the increase of MEA concentration and temperature. When the lean loading of MEA solvent is increased, efficiency of the removal process is decreasing. The liquid and vapour phase temperature profiles and CO2 loading in the absorber are analyzed to understand the model behaviour.

Ultrasonic degradation of butadiene, styrene and their copolymers

Ultrasonic degradation of commercially important polymers, styrene–butadiene (SBR) rubber, acrylonitrile–butadiene (NBR) rubber, styrene–acrylonitrile (SAN), polybutadiene rubber and polystyrene were investigated. The molecular weight distributions were measured using gel permeation chromatography (GPC). A model based on continuous distribution kinetics approach was used to study the time evolution of molecular weight distribution for these polymers during degradation. The effect of solvent properties and ultrasound intensity on the degradation of SBR rubber was investigated using different pure solvents and mixed solvents of varying volatility and different ultrasonic intensities.

Effect of Solvent Properties on Limiting Currents and Concentration Profiles in Non-Aqueous Electrolytes

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Investigation on the Rheological Behaviors of Styrene- Butaidene- Styrene Block Copolymer Solution

The viscoelastic behaviors of cyclohexane and dimethylbenzene SBS solutions with different concentrations have been investigated through dynamic rheological methods. The effects of solvent properties, concentration, stress and frequency on the rheological behaivors of SBS solutions have been carried out. The results show that the curves of dynamic shear stress tests show two modulus plateau, the dynamic moduli of dimethylbenzene SBS solutions are higher than those of the cyclohexane SBS solutions because dimethylbenzene is good solvent for SBS and the viscoelastic behaviors of solutions exhibit strong dependence on concentration.

Dissolution rates of silicate minerals in water from a subcritical to a supercritical state: effect of solvent properties

Hydrothermal reaction experiments of silicate minerals (actinolite, pyroxene, etc.) were carried out using flow-through reactors in the temperature range from 25 to 400 °C at 23 MPa. The dissolution in water of a multi-oxide silicate mineral, for example actinolite or pyroxene may require the breaking of more than one type of metal–oxygen bond. Differences between the rates at which these bonds break are often sufficiently large for dissolution to be non-stoichiometric. Dissolution rates (of Si) for actinolite and pyroxene in water were found to increase with increasing T from 25 to 300 °C, and then decrease with increasing T from 300 to 400 °C. The maximum release rates of Si are reached at 300 °C. The different metals in the minerals often have different release rates at a fixed temperature. At T < 300 °C the release rates of Na, Ca, Mg, Fe, and Al from minerals are usually higher than that of Si. In contrast, release rates of Si are higher than those of the others at T ≥ 300 °C. The hydrolysis of Si–O–Si bonds and metal ion-H+ exchange reactions at T < 300 °C are different from reactions at T ≥ 300 °C, at 23 MPa, because the solvent properties of water (decreasing density and dielectric constant in the region from sub-critical to supercritical state) affect reaction rates. log r (dissolution rates of Si) increases with 1/dielectric constant, as the temperature rises to close to 300 °C (or up to 374 °C) and at the critical pressure.

Determination of Dissociation Constants of Folinic Acid (Leucovorin), 5-Fluorouracil, and Irinotecan in Hydro-organic Media by a Spectrophotometric Method

In this study, a multiwavelength spectrophotometric method was used for the determination of the dissociation constants of drugs used for treatment of colorectal cancer, folinic acid (leucovorin), 5-fluorouracil, and irinotecan, in water and acetonitrile−water binary mixtures up to a 0.50 volume fraction at 25 °C and an ionic strength of 0.1 mol·L−1 KCl. The absorbance/pH profiles were assessed and found to conform to those of polyprotic acids. Data evaluation was performed using the STAR software program which calculates stability constants and molar absorbances of the pure species by multilinear regression. A linear relationship between acidity constants and the mole fraction of acetonitrile in the solvent mixture was observed. The effect of solvent properties on acid−base behavior is discussed.

Spectrophotometric determination of the acidity constants of calcon in water and mixed water-organic solvents

The acid-base properties of calcon (1-(2-hydroxy-1-naphthylazo)-2- -naphthol-4-sulfonic acid) in water and mixed water-organic solvents at 25 ?C at an ionic strength of 0.10 M are studied by a multiwavelength spectrophotometric method. The organic solvents used were the amphiprotic (methanol), dipolar aprotic (dimethylsulfoxide), and low basic aprotic (acetonitrile). To evaluate the pH absorbance data, a resolution method based on the combination of soft- and hard-modeling was applied. The acidity constants of all related equilibria were estimated using the whole spectral fitting of the collected data to an established factor analysis model. The data analysis program Datan was applied for determination of the acidity constants. The corresponding pKa values were determined in water and mixed water-organic solvents. Linear relationship between the acidity constants and the mole fraction of the different solvents in the mixtures exist. The effect of solvent properties on acid-base behavior is discussed.