Saturation Of Solvent Research Articles

Understanding the Electric Double Layer at the Electrode-Electrolyte Interface: Part I - No Ion Specific Adsorption.

In this work, we present a mean-field model that takes into account the key components of electrical double layer theory at the interface between an electrode and an electrolyte solution. The model considers short-range specific interactions between different species, including electrode-ion repulsion, the hydration of ions, dielectric saturation of solvent (water), and excluded volume (steric) interactions between species. By solving a modified Poisson-Boltzmann equation, which is derived from the grand thermodynamic potential of an inhomogeneous electrolyte solution, and using the appropriate results of quantum chemistry calculations on the hydration of ions, we can accurately approximate the differential capacitance profiles of aqueous electrolyte solutions at the boundary with a silver electrode. The specific interactions between the ions and the electrodes in the systems under consideration (aqueous solutions of NaClO4 and KPF6) are assumed to be significantly weaker than their Coulomb interactions. A novel aspect of our research is the investigation of the impact of short-range ion-water interactions on the differential capacitance, which provides new insights into the behavior of the electrical double layer. This model has the potential to be useful for electrochemical engineers working on the development of supercapacitors and related electrochemical energy storage devices. It serves as a basis for future modeling of electrolyte systems on real electrodes, especially in scenarios where chemical ion-electrode interactions are significant.

Assembling Alkaline-Responsive Chitosan@Giant Liposomes through an Ultrasound-Integrated Microfluidic Approach.

This paper presents the fabrication of an alkaline-responsive drug carrier, chitosan@giant liposome (CS-GL), by using an ultrasound-integrated microfluidic approach. On the microfluidic chip, water/oil/water droplets are first prepared and then move through an area of ultrasonic radiation to improve the regional saturation of organic solvent and accelerate its removal. At the same time, phospholipid molecules in the oil phase of the droplets are efficiently self-assembled into giant liposomes (GLs). Subsequently, microfluidic channels combined with an up-down separated structure can help in the fabrication and purification of the GLs. Due to the electrostatic interaction between the amino group of chitosan and the phosphate group of phospholipids, the GLs and chitosan are assembled into CS-GLs. The change of ζ potential after this operation indicates that chitosan is coated on the surface of GLs. The formed CS-GLs are monodispersed with a 54.1 ± 0.7 μm diameter and high drug encapsulation efficiency (∼96%), and the structural integrity can be kept without leakage of contents for more than a week in an acid medium (pH = 1.2). When this structure is placed in an aqueous solution of pH = 7.8, chitosan precipitates gradually and detaches from the GL, causing its rupture. The drug encapsulated in a single CS-GL can be rapidly released within 4 s, and 99.6% of the CS-GL carriers can complete the release within 10 min.

Development of generalized and simplified models for supercritical fluid extraction: Case study of papaya (Carica papaya) seed oil

The present study described the experimentation and modeling of supercritical CO2 extraction (SCE) process for papaya seed oil. Experiments were performed at various ranges of SCE parameters; temperature (303.15–368.15)K, pressure (15–35)MPa, solvent flow rate (5–25)g/min, particle size (0.2–1.4)mm and co-solvent (ethanol) flow rate as (0–20)% of CO2 flow rate. Obtained oil was analyzed through gas chromatography to estimate fatty acid concentrations. Effects of SCE parameters were investigated on the extraction yield and oleic acid concentration of papaya seed oil through central composite design. Further, two mathematical models (PM-1 and PM-2) were developed based on desorption–diffusion–dissolution (PM-1) and broken and intact cell (PM-2) mechanisms. These models were validated with the experimental data of papaya seed oil and further compared with the existing models. PM-1 proposed an equilibrium relation while assuming saturation of solvent and solute at interphase, which was successfully validated with the experimental data in the AARD range from 0.40% to 32.48%. PM-2 reduced the three zones of extraction curves to two and better fitted the experimental data of papaya seed in the AARD range from 0.45% to 35.62%. Model parameters of PM-2 were optimized through genetic algorithm.

Saturation reduces in-vitro leakage of monomers from composites

ObjectiveAccurate knowledge of the quantity of released monomers from composites is important. To evaluate the elution of monomers, polymerized composites are typically immersed in an extraction solvent. The objective was to determine whether the volume of extraction solvent and the immersion time influences monomer leachability from dental composite materials. MethodsComposite disks of two commercial composites, (Filtek Supreme XTE, 3M ESPE and G-aenial Universal Flo, GC) were prepared. The disks (n=10) were placed in a glass vial with 1ml, 2ml or 3ml of extraction solvent (100% ethanol with deuterated diethylphalate as internal standard). After either 7 or 30 days at 37°C, the supernatant was collected and the amount of released monomers (BisEMA, BisGMA, UDMA, TEGDMA) and bisphenol A was measured with liquid chromatography mass spectroscopy. ResultsFor both tested composites, the highest amount of released monomers was measured after sample incubation in 3ml, while the lowest amount was measured in 1ml of extraction solvent. Furthermore, 30 days did not result in much more monomer release compared to 7 days, and for most monomers, there was no statistically significant difference in release between 7 and 30 days. SignificanceRelease kinetics in in-vitro experiments are also influenced by saturation of the extraction solvent with the leached monomers. This is important as it is unlikely that saturation can be reached in an in-vivo situation, where saliva (or pulpal fluid) is continuously refreshed. Saturation of the extraction solvent can be avoided in-vitro by refreshing the extraction medium after equal time intervals.

An In Situ Investigation into the Formation of the Solvent‐Induced Crystalline Phase of Poly(9,9‐Dioctylfluorene) in Solvent Vapor Annealing

A new metastable solvent‐induced clathrate liquid crystalline phase of β phase (named β' here) in crystalline poly(9,9‐dioctylfluorene) (PFO) thin film induced by solvent annealing is found by a combination of in situ ultraviolet and visible spectrophotometry (UV‐vis), photoluminescence spectroscopy (PL), and grazing incidence wide‐angle X‐ray scattering (GIWAXS). The solvent annealing process consists of three processes: diffusion of solvent molecules into the film; saturation of solvent in the film; and drying of the film under nitrogen. The formation of β' phase with ordered packing of side chains and disordered packing of backbones occurs during the diffusion process of solvent molecules into the film. When the solvent molecules penetrate the film, the disordered side chains start to align themselves to form an ordered structure, and the ordering would gradually in the saturationprocess. Furthermore, the ordering of side chains drives an ordered rearrangement of the backbones during the drying process; however, the crystallinity of the side chains decreases with the orderly rearrangement of backbones due to the helical conformation of PFO. image

Microwave assisted synthesis of caffeine/maleic acid co-crystals: the role of the dielectric and physicochemical properties of the solvent

In the present work microwave radiation has been used to prepare the 1 : 1 and 2 : 1 co-crystals of caffeine and maleic acid. We obtained 1 : 1 co-crystals in the presence of water and methanol and we also see Form II of the 1 : 1 co-crystal in methanol. Co-crystallisation under microwave irradiation is shown to be controlled by the saturation of solvent at the reacting interface between the co-crystal components as well as the solvent dielectric properties.

Equipment for Low Temperature Steady-State Growth of Silicon from Metallic Solutions

Low temperature steady-state solution growth of silicon from indium on Si(001) substrates with a vertical stack of feeding source, solution, and substrate in top down position is demonstrated. The equipment especially designed for this task is presented. By applying different heating strategies the vertical temperature difference in the crucible wall is adjusted to meet the demands of the three stages of processing, that is, Si dissolution and homogenization, growth, and recycling of the solute. Heating from either the bottom or sides results in a temperature difference that should be suitable for growth. However, only for side heating growth has been observed. In order to understand this effect, numerical modeling of heat transfer and fluid flow has been performed. Heating from the side initiates a flow path, which allows both effective saturation of solvent at the feeding source and significant supersaturation at the substrate. In this case the epitaxial growth of pyramids with {111} facets on Si(001) s...

Enzymatic synthesis of isoamyl acetate using immobilized lipase from Rhizomucormiehei

The effects of important reaction parameters for enhancing isoamyl acetate formation through lipase-catalyzed esterification of isoamyl alcohol were investigated in this study. Increase in substrate (acid) concentration led to decrease in conversions. A critical enzyme concentration of 3 g l −1 was detected for a substrate concentration of 0.06 M (each of alcohol and acid). Solvents with partition coefficient higher than 1000 (log P>3.0) supported enzyme activity to give high conversions. Acetic acid at higher concentrations could not be esterified easily probably owing to its role in lowering the microaqueous pH of the enzyme. Extraneous water/buffer addition decreased the isoamyl acetate yields slightly (∼10%) at 0.005–0.01% v/v of the reaction mixture and drastically (>40%) at above 0.01% v/v. Buffer saturation of the organic solvent employed improved esterification (upto two-fold), particularly at moderately higher substrate concentrations (>0.18 M). Employing acetic anhydride instead of acetic acid resulted in a two-fold increase in the yields (at 0.25 M substrate). Use of excess nucleophile (alcohol) concentration by increasing the alcohol/acid molar ratio resulted in higher conversions in shorter duration (upto eight-fold even at 1.5 M acetic acid). Yields above 80% were achieved with substrate concentrations as high as 1.5 M and more than 150 g l −1 isoamyl acetate concentrations were obtained employing a relatively low enzyme concentration of 10 g l −1. The operational stability of lipase was also observed to be reasonably high enabling ten reuses of the biocatalyst.

Solubility of butane in several polar and nonpolar solvents and in an acetone-butanol solvent solution

Solubllltles of butane are reported at 101.325 kPa and for temperatures ranging from 283.15 to 313.15 K In the nine solvents benzene, cyclohexane, methanol, ethanol, lpropanol, 1-butanol, acetone, methyl ethyl ketone, and aniline, and also in two-component, acetonel-butanol, mlxed solvent solutlons. The solublllty was determlned by utlllzing the Increase In mass resuitlng from the saturation of solvent with butane gas at constant temperature and pressure.

Solute-Solvent Interactions in Ion Pair Extraction of Tetraalkylammonium Iodides. II. The Effect of Hydration of Iodide in Organic Solvents on the Extraction Constant

Abstract Solubilities of tetraalkylammonium iodides Et4NI, Pr4NI, and Bu4NI in nitrobenzene, in water, and in their mutually saturated solvents, and of Pr4NI in 1,1-dichloroethane and in its water saturated solvent were measured at 25 °C. Conductances of Et4NI, Pr4NI, and Bu4NI in nitrobenzene and Bu4NI in 1,1-dichloroethane, 1,2-dichloroethane, and dichloromethane have also been measured at 25 °C. A small amount of water in organic solvents increases the solubilities of the salts roughly twice those in pure solvents and decreases the association constants around 15% while a small amount of organic solvent in water gives a slight effect. Effects of mutual saturation of water and organic solvent on extraction equilibria of R4NI were discussed in terms of the selective hydration of the iodide.