Effect Of Cosolvents Research Articles

Effects of Different Surfactant and Furan Cosolvents on the Macroscopic and Microscopic Properties of Ethanol-Diesel Fuel Blends

Effects of Different Surfactant and Furan Cosolvents on the Macroscopic and Microscopic Properties of Ethanol-Diesel Fuel Blends

Rheology and Stability of Hydrocarbon-Based Gelled Fuels for Airbreathing Applications

Gelled fuels are rheologically complex, non-Newtonian fluids. They combine the benefits of both liquid and solid states, reducing risks of leakage, spilling, and sloshing during storage while maintaining the ability to be sprayed inside a combustion chamber. Additionally, suspending energetic particles, such as metal powders of aluminum and boron, can significantly enhance their energy density compared to conventional liquid fuels. In this study, several kerosene-based and ethanol-based formulations were experimentally investigated, using both organic and inorganic gelling agents. The compositions were optimized in terms of the gellant amount and manufacturing process. Some of the most promising gellants for kerosene include fatty acids, such as Thixcin® R or THIXATROL® ST, and metallic soaps, such as aluminum stearate and zinc stearate. The effects of various co-solvents were assessed, including ketones (methyl isoamyl ketone, methyl ethyl ketone, and acetone) and alcohols (ethanol and octadecanol). Sugar polymers like hydroxypropyl cellulose were tested as gelling agents for ethanol. A preliminary rheological analysis was conducted to characterize their behavior at rest and under shear stress. Finally, a novel approach was introduced to study the stability of the gels under vibration, which was derived from a realistic mission profile of a ramjet. Finally, the ideal gravimetric specific impulse was evaluated through ideal thermochemical computations. The results showed that promising formulations can be found in both kerosene-based and ethanol-based gels. Such compositions are of interest in practical airbreathing applications as they have demonstrated excellent stability under vibration, ideal combustion properties, and pronounced shear-thinning behavior.

Comparative Study of Polymer Globules and Liquid Droplets in Poor Solvents: Effects of Cosolvents and Solvent Quality.

We compare the structures of polymer globules, composed of flexible polymer chains, with liquid droplets made of nonbonded monomers of the same polymer in poor solvents. This comparison is performed in three different poor solvents, with and without the addition of cosolvents. Molecular dynamics simulations are used to analyze the properties of the polymer globules, while semigrand canonical Monte Carlo simulations are used to form metastable liquid droplets of nonbonded monomers through homogeneous nucleation in the same solvents. Our findings show that both globules and droplets are nearly spherical, although droplets display slightly more anisotropy. In the absence of cosolvents, the surrounding solvent structures are similar for both globules and droplets. However, in the presence of cosolvents, significant differences arise in the liquid structure, with the disparities increasing as the solvent quality worsens. Cosolvents tend to accumulate near the surface of globules due to the restricted movement of bonded monomers, which partially immobilizes the cosolvents. This effect becomes more pronounced as the solvent quality declines. Interfacial free energy calculations reveal that cosolvents act like surfactants, promoting larger interfacial areas for both globules and droplets. This effect is more significant for globules due to the greater accumulation of cosolvents at their surface. Therefore, modeling polymer globules as liquid droplets may underestimate the impact of cosolvents on the stability of the globule state. Additionally, the transition states involved in polymer collapse in the presence of cosolvents differ from those involved in the nucleation of liquid droplets in the same solution.

Effects of Cosolvent and Nonsolvating Solvent on the Structural Dynamics of Organic Electrolytes in Sodium-Ion Batteries.

In sodium-ion batteries (SIBs), the performance of a single solvent often does not meet actual requirements and a cosolvent or nonsolvating solvent is needed. However, the effect of these electrolyte additives on the solvation structure and dynamics of Na+ in SIBs is yet to be fully understood. Herein, electrolyte structural dynamics are examined for NaPF6 in dimethyl carbonate (DMC) with 1,1,2,2-tetrafluoro-2,2,2-trifluoroethoxy ethane (HFE) as the nonsolvating solvent or propylene carbonate (PC) as the cosolvent using steady-state and time-resolved infrared (IR) spectroscopies. Molecular dynamics simulations show that the solvation size of Na+ decreases with a loosened structure upon adding the nonsolvating solvent, whereas its first solvation shell becomes denser and the second one becomes softened with decreased participation of the PF6- anion upon adding the cosolvent. While a decreased participation of DMC in the solvation layer of Na+ is suggested by linear IR results, an increased structural inhomogeneity (and hence overall more dynamical fluctuations) is found for Na+-coordinated DMC upon adding both additives by two-dimensional (2D) IR spectroscopy where the carbonyl stretch is used as a probe. The Na+/DMC/PC complex is found to structurally evolve slower than both Na+/DMC and Na+/DMC/HFE complexes on the picosecond time scales by spectral diffusion dynamics extracted from 2D IR diagonal signals. Frontier orbital theory calculations also indicate that both solvent additives are beneficial to increasing the stability of PF6-. The results obtained in this work provide important insights into the roles played by the solvent additives in influencing the solvation structures and dynamics of Na+, which are critical for understanding the Na+ transfer mechanism in SIBs.

Effect of Co-Solvents, Modified Starch and Physical Parameters on the Solubility and Release Rate of Cryptotanshinone from Alcohologels.

(1) Background: The aim of the work was to investigate the influence of selected physico-chemical factors on the solubility and release rate of CT (cryptotanshinone) in alcohologels. (2) Methods: The alcohologels of methylcellulose (MC), hydroksyethylcellulose (HEC), polyacrylic acid (PA) and polyacrylic acid crosspolymer (PACP) with CT were prepared and/or doped with native potato starch (SN) and modified citrate starches (SM2.5 and SM10). The analytical methods included evaluation of CT release profiles, Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and electrospray ionization mass spectrometry (ESI-MS), and scanning electron microscope (SEM) images were performed. (3) Results: The release and decomposition kinetics of CT in relation to the phosphate buffer solution (PBS) and methanol were observed. The amount of cryptotanshinone (CT) released into PBS was significantly lower (2.5%) compared to its release into methanol, where 22.5% of the CT was released into the model medium. The addition of SM2.5 to the alcohologel significantly increased the CT content to 70% in the alcohologel preparation containing NaOH (40%), and this enhanced stability was maintained for up to two months. The ATR-FTIR exhibited interactions between PA and 2-amino-2-methyl-1,3-propanediol (AMPD) as well as between PA and NaOH in case of the alcohologels. Moreover, it indicated the interaction between CT and NaOH. PXRD diffractograms confirmed the FTIR study. (4) Conclusions: The study observed the influence of a number of factors on the solubility and release rate of CT, as: alkalizers and their concentration, SM2.5 addition. The transition of CT in the presence of NaOH to the tanshinone V sodium (T-V sodium) form was suspected.

Boosting Mg deposition and dissolution from ionic liquids – The role of different additives for applications in Mg-ion batteries

In this work, Mg deposition from 0.1 M Mg(TFSI)2 dissolved in a hydrophobic ionic liquid (IL) is found to occur, regrettably at very high overpotential, which is accompanied by electrolyte decomposition. To address this issue, we have systematically improved the electrochemical performance of the Mg-IL system through three stages of electrolyte optimization. The first two stages involved investigating the effects of different co-solvents and Mg(BH4)2 as electrolyte additives, while the third stage comprised a detailed study of various ratios between the ionic liquid and different co-solvents to achieve an optimized system. Notably, a ratio of 1:3 MPPip-TFSI to diglyme exhibited higher cathodic and anodic currents, lower overpotential, and improved cycling stability compared to other co-solvents. Scanning electron microscopy micrographs and X-ray diffraction revealed uniform and reversible Mg deposition and dissolution. The optimized electrolyte was tested with WS2/PANI as cathode material to validate our electrolyte system in a Mg battery application, achieving a specific capacity of 197 mAh∙g−1 at 20 mA∙g−1 at room temperature.

Minimizing solvated water via synergistic effect of salt anion and cosolvent enables stable Zn metal anodes in low-cost acetate electrolyte

Aqueous zinc metal batteries (ZMBs) have attracted increasing attention in the past decades owing to their potentially low cost and non-flammability. However, the poor Coulombic efficiency (CE) and short lifespan caused by side reactions (e.g., H2 evolution) and dendrite growth limit the practical applications of ZMBs. Given that H2 evolution is primarily originated from solvated water, here, a low-cost acetate-based electrolyte constituted by 1 m ZnAc2 and 5 m KAc in an 80:20 water:trimethyl phosphate (TMP) (v/v) mixture is proposed to minimize solvated water and boost the electrochemical performance of aqueous ZMBs without compromising intrinsic advantages of the aqueous electrolyte. The relatively high abundance of Ac− enables preferential coordination with Zn2+, meanwhile, the addition of TMP not only further replaces water molecules in the inner solvation shell, but also significantly interrupts the H-bond network of water. Improved electrochemical performance are demonstrated in Zn||Zn and Zn||Cu half-cells and Zn||I2 full cells.

Effects of Cosolvent on the Intermolecular Interactions between an Analyte and a Gold Nanostar Surface Studied Using SERS.

For surface-enhanced Raman scattering (SERS), reproducible solution-phase results are typically obtained using nanoparticles functionalized with surface-stabilizing molecules that can prevent the adsorption of analyte molecules with surface affinities lower than those of the stabilizing agent. Herein, we investigate the effects of intermolecular interactions between a nonthiolated analyte and cosolvent to facilitate and modulate analyte adsorption to gold nanostars. SERS, extinction spectroscopy, transmission electron microscopy (TEM), and density functional theory (DFT) calculations are employed in this regard. Tetrahydrofuran (THF) is utilized as a cosolvent in water to facilitate the detection of acetylsalicylic acid (aspirin) on anisotropic gold nanoparticles. Intermolecular interactions between the analyte, solvent, and surface are modulated by changing the solution composition to understand how THF facilitates the SERS detection of aspirin in THF-water cosolvents. SERS signals for 5 mM aspirin arise only in the presence of THF at and above 60 mM, while no signal with or without THF below 60 mM is observed. SERS detection of aspirin is hypothesized to depend on THF forming a hydrogen-bonded complex with aspirin that reduces aspirin hydrophobicity, thus stabilizing the acid form of the molecule and allowing it to weakly interact with the gold nanoparticles. The aspirin-THF complex adsorbs to the gold surface through π-orbital overlap between the aromatic ring and gold, where additional THF weakens orbital overlap. Understanding the mechanism by which organic cosolvents facilitate the SERS detection of nonthiolated analytes such as aspirin, in aqueous media, allows other cosolvents, nonthiolated analytes, and other surfaces to obtain a SERS signal in a variety of systems.

Optimization of oil extraction from Melia azedarach fruits using methanol-modified SC-CO2 for highly efficient biodiesel production using a modified LAC catalyst

A highly efficient oil extraction method including modified Supercritical carbon dioxide (SC-CO2) with co-solvents was applied for oil extraction from Melia azedarach fruits and then using a modified LAC (luffa activated carbon) catalyst, the oil was converted to biodiesel for the first time. The effect of pressure (22–30 MPa), temperature (40–80 °C), extraction time (0–240 min) and co-solvent (methanol and n-hexane) were determined on SC-CO2 extraction to obtain the optimum condition. The optimum extraction conditions for Melia azedarach oil corresponded to a pressure of 30 MPa and temperature of 40 °C at 180 min using methanol as of co-solvent. The maximum yield was obtained by addition of methanol as co-solvent in an amount of 10 %, w/w. The methanol- modified SC-CO2 extraction oil yield was 43 % (w/w) and the oil yield by n-hexane-modified SC-CO2 extraction was 38 %, while the oil yield obtained by pure SC-CO2 extraction was 32 %. Then, the effect of catalysts LAC-NH2 and LAC-N(Et)2 as safe, economical, free-metal, and less time-consuming heterogeneous catalysts was investigated on biodiesel production from extracted oil. The results revealed that the optimum yields of 98 % was obtained for biodiesel production using 2 wt% of LAC-NH2 catalyst at the reaction conditions of oil to methanol ratio of 1:6, reaction temperature of 60 °C, and reaction time of 3 h.

Aqueous co-solvent synthesis of Zeolitic Imidazolate Frameworks: The impact of co-solvents in the crystal growth kinetics

Zeolitic Imidazolate Frameworks (ZIFs) have been widely studied in recent decades in a variety of applications. However, a fundamental understanding of crystal growth kinetics as well as their formation mechanisms has been very limited. Underpinning such mechanisms might be of key importance for the predictable synthesis of ZIFs to rationally tune the structural and morphological properties for respective applications. Herein, the crystal growth kinetics and structural evolution of ZIF-8 crystals in various aqueous co-solvent reaction environments were studied with respect to synthesis time. By tracking the nucleation, crystal growth, stabilization and ripening, three potential kinetic formation mechanisms were proposed. More specifically, with methanol, isopropanol and acetone, a fast nucleation rate and crystal growth occurred within 60 minutes (min) at room temperature. However, ethanol and n-propanol showed prolonged nucleation which resulted in the slow formation of ZIF-L/ZIF-8 mixed phases at the early stage. Phase transformation to pure ZIF-8 was observed in longer syntheses. Nitrogen-containing solvent, N, N–dimethyl formaldehyde (DMF), was found to induce both nucleation and growth, resulting in large crystals in less than 60 min of fabrication. In each case, the crystal formation follows Avrami's classical model. Hence, by understanding the effects of co-solvents in ZIF nucleation, crystallization and phase selection, one can rationally design the crystals with predictable crystallinity, size, morphology, purity and surface properties for targeted applications such as adsorption of small molecules from aqueous mixtures.

Liquid-Liquid Equilibrium of Sesame Fatty Acid (Ethyl and Methyl) Ester + Glycerol + Ethanol/Methanol Mixtures at Different Temperatures.

This study aimed to investigate the liquid-liquid equilibrium (LLE) behavior of sesame fatty acid ethyl ester (FAEE) and methyl ester (FAME) in combination with glycerol and the co-solvents ethanol and methanol. FAEE and FAME were produced through the transesterification of mechanically extracted and purified sesame oil, using potassium hydroxide (KOH) as a homogeneous base catalyst. The reactions were conducted in ethanol and methanol to produce FAEE and FAME, respectively. Post-reaction, the products were separated and purified, followed by an analysis of the LLE behavior at 313.15 K and 323.15 K under atmospheric pressure (101.3 kPa). The experimental process for the miscibility analysis utilized a jacketed glass cell adapted for this study. Miscibility limits or binodal curves were determined using the turbidity-point method. Tie lines were constructed by preparing mixtures of known concentrations within the two-phase region, which allowed the phases to separate after agitation. Samples from both phases were analyzed to determine their composition. This study revealed that higher temperatures promoted greater phase separation and enhanced the biodiesel purification process. The NRTL model effectively correlated the activity coefficients with the experimental data, showing good agreement, with a root-mean-square deviation of 3.5%. Additionally, the data quality was validated using Marcilla's method, which yielded an R2 value close to 1. Attraction factors and distribution coefficients were also calculated to evaluate the efficiency of the co-solvents as extraction agents. The findings indicated higher selectivity for methanol than for ethanol, with varying degrees of distribution among the co-solvents. These results offer significant insights into enhancing biodiesel production processes by considering the effects of co-solvents on the LLE properties of mixtures, ultimately contributing to more efficient and cost-effective biodiesel production.

Molecular Mechanism of the Cosolvency Effect in Organic Solutes with Similar Structures

Molecular Mechanism of the Cosolvency Effect in Organic Solutes with Similar Structures

Co-Solvent effect and Kinetics of Alkaline Hydrolysis of Butyle Salicylate

The base catalised hydrolysis of buyl salicylate has been carred out in water-DMF binary solvent mixture covering range of 30 to 70% (v/v) of solvent composition at different Temperature (20 to 400 C). The reaction followed second order rate constant which decreases with increase of solvent composition. The salvation and desolvation concept are used to explain the solvent influence on rate and mechanism is the reaction. The relation between changes in dielectric constant due to variation of reaction mixture and change in specific rate constant has been explained on the basis of electrostatic and non-electrostatic contribution of solvent mixture. Calculated value of Iso-composition activation energy is found to be increases with increase of solvent composition. The thermodynamic parameters (ΔG*, ΔH* & ΔS*) has been determined with help of Wynne Jone and Eyring equation which show the great dependency on solvent composition.

Effects of Macromolecular Cosolutes on the Kinetics of Huntingtin Aggregation Monitored by NMR Spectroscopy.

The effects of two macromolecular cosolutes, specifically the polysaccharide dextran-20 and the protein lysozyme, on the aggregation kinetics of a pathogenic huntingtin exon-1 protein (hhtex1) with a 35 polyglutamine repeat, httex1Q35, are described. A unified kinetic model that establishes a direct connection between reversible tetramerization occurring on the microsecond time scale and irreversible fibril formation on a time scale of hours/days forms the basis for quantitative analysis of httex1Q35 aggregation, monitored by measuring cross-peak intensities in a series of 2D 1H-15N NMR correlation spectra acquired during the course of aggregation. The primary effects of the two cosolutes are associated with shifts in the prenucleation tetramerization equilibrium resulting in substantial changes in concentration of "preformed" httex1Q35 tetramers. Similar effects of the two cosolutes on the tetramerization equilibrium observed for a shorter, nonaggregating huntingtin variant with a 7-glutamine repeat, httex1Q7, lend confidence to the conclusions drawn from the fits to the httex1Q35 aggregation kinetics.

Recent Advances of Solvent Effects in Biomass Liquefaction Conversion

Liquefaction conversion technology has become one of the hottest biomass conversion methods due to its flexible material selection and extensive product applications. Exploring biomass liquefaction conversion focuses on catalysts, biomass/water ratio, and reaction temperature. However, it is found that solvents are crucial in the biomass liquefaction process and significantly impact the type of liquefied products and bio-oil yield. Given the current rapid development trend, timely sorting and summary of the solvent effect in the biomass liquefaction process can promote the subsequent development and industrialization of more efficient and cleaner biomass liquefaction technology. Therefore, this review first introduces the characteristics of water as the liquefaction solvent, then summarizes the effects of organic solvents on liquefaction, and finally elaborates on the synergistic effect of co-solvents, which provides a more systematic overview of solvent effects in the liquefaction process. Meanwhile, prospects are put forward for the future development of biomass liquefaction conversion.

Influence of Surfactant on the Skin Permeation of Methylisothiazolinone and Methylchloroisothiazolinone

Patch tests are often used in safety evaluations to identify the substance causing skin irritation, but the same substance can sometimes give positive or negative results depending on the test conditions. Here, we investigated differences in the skin penetration of two test compounds under different application conditions. We studied the effects of the anionic surfactant sodium dodecyl sulfate (SDS) and the nonionic surfactant polysorbate 80 (PS) on skin penetration of the preservatives methylisothiazolinone (MT) and methylchloroisothiazolinone (MCT), which are used in cosmetics such as shampoos. The skin permeation of MT was enhanced by SDS but was unchanged by PS. Skin impedance decreased in the presence of SDS whereas PS had the same effect as the control aqueous solution, suggesting that SDS reduction of the barrier function of skin affects the permeation of MT, a hydrophilic drug. Application of a mixture of MCT and MT in the presence of SDS did not affect the skin permeation of MCT whereas the permeation of MT was enhanced by SDS, indicating that the skin permeation of MCT is less affected by SDS than is MT. Thus, attention should be paid to the possible effect of co-solutes, especially hydrophilic drugs.

Bioinspired Colorimetric Double Inverse Opal Photonic Crystal Indicators for Ethanol Concentration Sensing in Fermentation Engineering.

Photonic crystal-based ethanol concentration indicators with rapid response and brilliant structural color output definitely take a place in colorimetric sensors. Here, based on the H-bond-regulated swelling of acrylate shape memory polymers (SMPs) and the solvent-induced structural color change of the double inverse opal photonic crystals (DIOPCs), new-type photonic crystals (PCs) colorimetric indicators were constructed, exhibiting a span of maximum reflection wavelength (λmax) up to ∼166 nm in response to alcohols with concentrations from 0 to 100 vol %. DIOPC indicators (DIOPCIs) show a rapid response to alcohols (<1.5 s) and output different structural colors (covering from blue to red). The colorimetric sensing mechanism includes the solvent-triggered recovery of the inverse opal skeleton, the cosolvency effect and H-bonds induced swelling/shrinkage of the polymer, the phase separation between polystyrene (PS) microsphere and polymer skeleton, and the light diffraction of DIOPCs. While ensuring a larger λmax span by regulating the H-bond interactions in polymer chains through acrylamide (AAm), AAm-modified DIOPCIs are sensitive to some specific ethanol concentrations. The real-time sensing of ethanol concentration during fermentation verified the practicability of DIOPCIs, thus establishing a visual model between structural color and corresponding fermentation kinetics. We envisage that the DIOPCIs will contribute to the intelligentization of the alcoholic fermentation and distillation industry.

Experimental and Machine-Learning-Assisted Design of Pharmaceutically Acceptable Deep Eutectic Solvents for the Solubility Improvement of Non-Selective COX Inhibitors Ibuprofen and Ketoprofen.

Deep eutectic solvents (DESs) are commonly used in pharmaceutical applications as excellent solubilizers of active substances. This study investigated the tuning of ibuprofen and ketoprofen solubility utilizing DESs containing choline chloride or betaine as hydrogen bond acceptors and various polyols (ethylene glycol, diethylene glycol, triethylene glycol, glycerol, 1,2-propanediol, 1,3-butanediol) as hydrogen bond donors. Experimental solubility data were collected for all DES systems. A machine learning model was developed using COSMO-RS molecular descriptors to predict solubility. All studied DESs exhibited a cosolvency effect, increasing drug solubility at modest concentrations of water. The model accurately predicted solubility for ibuprofen, ketoprofen, and related analogs (flurbiprofen, felbinac, phenylacetic acid, diphenylacetic acid). A machine learning approach utilizing COSMO-RS descriptors enables the rational design and solubility prediction of DES formulations for improved pharmaceutical applications.

Effect of green co-solvents on properties and synthesis of cellulose esters in superbase ionic liquid

Effect of green co-solvents on properties and synthesis of cellulose esters in superbase ionic liquid

Controlling Interfacial Hydrogen Bonding at a Gold Surface: The Effect of Organic Cosolvents.

Water often serves as both a reactant and solvent in electrocatalytic reactions. Interfacial water networks can affect the transport and kinetics of these reactions, e.g., hydrogen evolution reaction and CO2 reduction reaction. Adding cosolvents that influence the hydrogen-bonding (H-bonding) environment, such as dimethyl sulfoxide (DMSO), has the potential to tune the reactivity of these important electrocatalytic reactions by regulating the interfacial local environment and water network. We investigate interfacial H-bonding networks in water-DMSO cosolvent mixtures on gold surfaces by using surface-enhanced infrared absorption spectroscopy and molecular dynamics simulations. Experiments and simulations show that the gold surface is enriched with dehydrated DMSO molecules and the mixture phase-separates to form water clusters. Simulations show a "buckled" water conformation at the surface, further constraining interfacial H-bonding. The small size of these water clusters and the energetically unfavorable H-bond conformations might inhibit H-bonding with bulk water, suppressing the proton diffusion required for efficient hydrogen evolution reaction processes.