Aqueous Solvent Systems Research Articles

Oiling out and solubility measurement, molecular simulation and thermodynamic properties of d-tagatose in four aqueous binary solvent systems at 283.15 to 323.15 K

Solubility of D-Tagatose in four aqueous binary solvent systems from 278.15 K to 323.15 K was determined using the anti-solvent assisted gravimetric method. The solubility increases with temperature in all four binary solvents, with water, a good solvent, exhibiting a similar trend. In addition, the dissolution process generally follows the ’like dissolves like’ rule. The study indicates that the oiling out occurs when water exhibits a high molar fraction in water + 1-propanol, and water + isopropanol. Furthermore, we study the charge of the molecule using the molecular electrostatic potential surface (MEPS), aiming to analyze the molecular interactions. Then, to explain the dissolution behaviors of D-tagatose, the radial distribution function (RDF) by molecular dynamics simulations (MD) revealed a strong correlation between solute–solvent interactions and solubility, with significant solvent–solvent interactions. The solubility data was correlated using the modified Apelblat equation, Van’t Hoff equation, λh equation, and Jouyban-Acree model, with demonstrating the high consistency in the data. Finally, the thermodynamic properties revealed that the dissolution process of D-Tagatose is endothermic, and entropy-driven based on all positive values for ΔsolHo, ΔsolSo, ΔsolGo.

Zinc Chemistries of Hybrid Electrolytes in Zinc Metal Batteries: From Solvent Structure to Interfaces.

Along with the booming research on zinc metal batteries (ZMBs) in recent years, operational issues originated from inferior interfacial reversibility have become inevitable. Presently, single-component electrolytes represented by aqueous solution, "water-in-salt," solid, eutectic, ionic liquids, hydrogel, or organic solvent system are hard to undertake independently the task of guiding the practical application of ZMBs due to their specific limitations. The hybrid electrolytes modulate microscopic interaction mode between Zn2+ and other ions/molecules, integrating vantage of respective electrolyte systems. They even demonstrate original Zn2+ mobility pattern or interfacial chemistries mechanism distinct from single-component electrolytes, providing considerable opportunities for solving electromigration and interfacial problems in ZMBs. Therefore, it is urgent to comprehensively summarize the zinc chemistries principles, characteristics, and applications of various hybrid electrolytes employed in ZMBs. This review begins with elucidating the chemical bonding mode of Zn2+ and interfacial physicochemical theory, and then systematically elaborates the microscopic solvent structure, Zn2+ migration forms, physicochemical properties, and the zinc chemistries mechanisms at the anode/cathode interfaces in each type of hybrid electrolytes. Among of which, the scotoma and amelioration strategies for the current hybrid electrolytes are actively exposited, expecting to provide referenceable insights for further progress of future high-quality ZMBs.

Preferential Solvation of Cyclosporin in Aqueous Mixtures of Some Polymeric Cosolvents

Background: Cyclosporin is a cyclic peptide-drug used as immunosuppressant for the prophylaxisof transplant rejection whose physicochemical properties in mixed aqueous solvent systems isstill not well understood. The preferential solvation parameters of cyclosporin in aqueous binarymixtures of diethylene glycol monoethyl ether (DEGME), polyethylene glycol 200 (PEG 200) andpolyethylene glycol 400 (PEG 400) were computed. Methods: Reported mole fraction solubilities of cyclosporin in DEGME-aqueous mixtures,PEG 200-aqueous mixtures, and PEG 400-aqueous mixtures were processed by following theinverse Kirkwood-Buff integrals (IKBI) method as suggested by Marcus and Ben-Naim using somethermodynamic parameters reported in the literature for these aqueous-polymeric mixtures at298.15 K. Results: It is observed that cyclosporin is sensitive to preferential solvation effects in theseaqueous-polymeric binary solvent systems. The preferential solvation parameter by DEGME (δx1,3)is negative in water-rich mixtures but positive in mixtures of 0.12<x1<1.00. It is conjecturablethat hydrophobic hydration around the non-polar methyl and methylene groups of this drug thatcould be present in water-rich mixtures can significantly impact the drug solvation. Otherwise,in mixtures of 0.12<x1<1.00 in DEGME-aqueous mixtures, as well as in almost all the mixtureswith PEGs, the preferential solvation by polymeric cosolvents could be due to the acidic behaviorof cyclosporin in front of ether and hydroxyl oxygen atoms of these polymeric cosolvents. Conclusion: Cyclosporin is preferentially solvated by the polymeric solvents in almost all thestudied mixtures of these aqueous-polymeric binary solvent systems.

Green and sustainable extraction of phycocyanin from Spirulina platensis by temperature-sensitive polymer-based aqueous two-phase system and mechanism study

In this study, a sustainable and environmentally friendly method was developed for the enrichment and purification of phycocyanin from Spirulina platensis. This was achieved by utilizing a temperature-sensitive polymer, Pluronic F68, in an aqueous two-phase solvent system. The phase behavior of the temperature-sensitive polymer-based biphasic system was evaluated. The extraction conditions were optimized by both single-factor experiments and response surface methodology. Under the optimal conditions, the upper polymer-rich phase was recycled for sustainable phycocyanin extraction, resulting in a grade of 3.23 during the third extraction cycle. Pluronic F68 could be efficiently recovered and reused during the extraction process. The interaction mechanism between Pluronic F68 and phycocyanin was systematically studied using FT-IR and fluorescence analysis. This was further complemented by static and dynamic calculation of molecular motion through molecular docking and molecular dynamics simulation, indicating that hydrophobic segment of Pluronic F68 played a key role in the binding process with phycocyanin.

Organocatalyzed Synthesis of Anti-tubercular Agents

Abstract: This review highlights synthetic developments of anti-tubercular agents by using organocatalysts. Organocatalysts-mediated synthesis is environmentally benign and highly compatible with aqueous-solvent systems, and such catalysts are attractive because of their inexpensive cost, low toxicity, good air and moisture stability and follow many principles of green chemistry. Numerous anti-tuberculosis agents have been synthesized utilizing organocatalysts and tested for their in-vivo and in-vitro anti-mycobacterial activity against Mycobacterium tuberculosis H37Rv pathogens. The inhibitory concentrations of the reported compounds were compared with the standard reference drugs in order to evaluate their inhibition potency.

A Novel Rhodamine-Phenolphthalein Architecture for Selective Mercury Ion Detection in Aqueous Media.

In this study, the primary objective is to synthesize a novel fluorescent Rh-PP-Rh compound and explore its extensive range of photochemical behaviors. Initially, the synthesis of the novel Rh-PP-Rh was carried out for this purpose. Subsequently, UV-Vis and fluorescence spectroscopy were employed to investigate the interactions between Rh-PP-Rh and a diverse array of ions in aqueous solvent systems. Through fluorescence and UV-Vis studies, it was observed that Rh-PP-Rh demonstrated turn-on sensor properties in the presence of Hg2+ ions. Furthermore, the limits of detection (LOD) and association constant (Ka) values for Rh-PP-Rh/Hg2+ were determined as 334 nM and 9.13×1011 M-2, respectively. Additionally, the reversible studies demonstrated a switchable on/off response upon alternate addition of HgCl2 and [Bu4N]F to Rh-PP-Rh. These findings suggest that the probe Rh-PP-Rh also possesses specific sensor properties for F- ions in the presence of mercury. In addition, the investigation encompassed an assessment of the visual analysis of the color alterations of Rh-PP-Rh both on filter paper and in an EtOH/H2O solution. The findings demonstrated that Rh-PP-Rh can be successfully utilized in solutions containing mercury, as it generates significant color transformations.

Design, synthesis and catalytic application of water-soluble 1,1′-bis(diphenylphosphino)ferrocene ligands

Hydrophilic phosphine ligands have proven indispensable for the translation of metal-catalyzed reactions into aqueous solvent systems and thus for the implementation of safe as well as sustainable chemical processes. Despite numerous reports on water-soluble variants of several renowned ligands, the dppf ligand family has been neglected thus far. Herein, we disclose synthetic strategies towards the first hydrophilic dppf derivatives overcoming issues typically encountered due to their intrinsic oxidizability. Core-sulfonated dppf ligands (meso‑2,2′- or 2,5-disubstituted) were prepared by a directed metalation strategy starting from diisopropyl ferrocene-1,1′-disulfonate. Alternatively, hydrophilic sulfonate or ammonium groups were introduced at the phenyl substituents of dppf. The novel ligands were spectroscopically characterized and showed their catalytic potential in the Pd-catalyzed Tsuji-Trost allylation of amines in water furnishing pharmaceutically relevant N-allylated products (e.g., naftifine, cinnarizine) through a scalable, safe and environmentally benign process.

Primena vodenih eutektičkih rastvarača za hemijsku valorizaciju otpadnog mulja - određivanje mineralnog sadržaja

Sewage sludge is a by-product of municipal wastewater treatment processes with significant soil-forming and fertilizing characteristics. However, if sewage sludge contains heavy metals, it can negatively affect the soil environment. The accumulation of heavy elements in the soil can negatively affect the circulation of elements in the natural environment, regarding plants, animals, and humans. The primary sources of heavy metals in human and animal food are plants, which are also the primary consumers of mineral nutrients from soil and water. Even a very small amount of heavy metals in the body can create metabolic problems, reduced body functions, and compromised immune and enzymatic processes, all of which contribute to various diseases and may even cause death. The aim of this study was to find a suitable system for mineral extraction from the municipal sewage sludge after water purification, collected from the wastewater treatment plant in Vlasotince, so the real composition of sewage sludge could be obtained. For that purpose, different aqueous deep eutectic solvents were applied: choline chloride:lactic acid (ChCl:LA), choline chloride:urea (ChCl:U), choline chloride:glycerol (ChCl:G), choline chloride:propylene glycol (ChCl:PEG), choline chloride:citric acid (ChCl:CA), and choline chloride:ethylene glycol (ChCl:EG).The concentrations of minerals after wet digestion were determined by Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES). The results showed that the highest amounts of minerals, especially Ca, P, and Fe, were extracted using aqueous acidic deep eutectic solvent systems (ChCl:LA and ChCl:CA). Also, the mineral composition of sewage sludge indicates the possibility of its use as a significant soil fertilizer supplement.

Superhydrophilic and Underwater Superoleophobic Copper Mesh Coated with Bamboo Cellulose Hydrogel for Efficient Oil/Water Separation.

Super-wetting interface materials have shown great potential for applications in oil-water separation. Hydrogel-based materials, in particular, have been extensively studied for separating water from oily wastewater due to their unique hydrophilicity and excellent anti-oil effect. In this study, a superhydrophilic and underwater superoleophobic bamboo cellulose hydrogel-coated mesh was fabricated using a feasible and eco-friendly dip-coating method. The process involved dissolving bamboo cellulose in a green alkaline/urea aqueous solvent system, followed by regeneration in ethanol solvent, without the addition of surface modifiers. The resulting membrane exhibited excellent special wettability, with superhydrophilicity and underwater superoleophobicity, enabling oil-water separation through a gravity-driven "water-removing" mode. The super-wetting composite membrane demonstrated a high separation efficiency of higher than 98% and a permeate flux of up to 9168 L·m-2·h-1 for numerous oil/water mixtures. It also maintained a separation efficiency of >95% even after 10 cycles of separation, indicating its long-term stability. This study presents a green, simple, cost-effective, and environmentally friendly approach for fabricating superhydrophilic surfaces to achieve oil-water separation. It also highlights the potential of bamboo-based materials in the field of oil-water separation.

Exploring solubility and energetics: Dissolution of biologically important l-threonine in diverse aqueous organic mixtures across the temperature range of 288.15 K to 308.15 K

This research provides a thorough investigation into the solubility behavior and solution thermodynamics of l-threonine in significant organic solvent systems. The work was done on measuring the actual solubility and subsequently calculating overall transfer solvation free energetics (∆Genergetic0i) and transfer entropies (∆St0i) at a temperature of 298.15 K. These measurements were performed as l-threonine transitioned from water to different water-organic mixed solvents systems. The saturated solubilities of l-threonine were determined using the ‘gravimetric method’ at five equidistant temperatures namely 288.15 K, 293.15 K, 298.15 K, 303.15 K and 308.15 K. By analyzing the data on solubility, we further obtained the different energies involved in solvation related issues. In the case of single solvents, the nature of solubility of l-threonine was observed like: dimethylsulfoxide (DMSO) < acetonitrile (ACN) < N, N-dimethylformamide (DMF) < ethylene glycol (EG) < water (H2O), irrespective of the experimental conditions. Specifically, at 298.15 K, the solubilities of l-threonine in single solvents were found to be as follows: 0.8220 mol per kg of water, 0.3101 mol per kg of EG, 0.1337 mol per kg of DMF, 0.1107 mol per kg DMSO and 0.1188 mol per kg of ACN. This research critically examines the relationship between the experimental saturated solubility of l-threonine and the complex properties influencing its solvation energy in diverse aqueous organic solvent systems.

Ether-type co-solvents of excellence for aqueous base-free Pt-catalyzed oxidation of concentrated 5-(hydroxymethyl)furfural to 2,5-furandicarboxylic acid

The biomass-derived 5-(hydroxymethyl)furfural (5-HMF) is readily converted in water to 2,5-furandicarboxyl acid (FDCA) that is well known as a renewable diacid monomer. However, the limited solubility of FDCA in water posed serious challenges to process development. Herein, the base-free Pt-catalyzed oxidation of 5-HMF was explored in aqueous binary solvent systems containing organic co-solvents such as dimethyl sulfoxide, N,N-dimethylformamide, gamma-valerolactone, dioxane, diethylene glycol dimethyl ether, and 1,2-dimethoxyethane (DME). The FDCA solubility and 5-HMF oxidation performance were investigated in co-solvent/H2O systems with different co-solvent fractions. When correlated with the solvatochromic parameters of co-solvents, the FDCA yield appeared to be in harmony with their polarizability and hydrogen bonding acceptance ability. Thus, infrared spectra were collected with three systems such as co-solvent/H2O, 5-HMF in co-solvent, and 5-HMF in co-solvent/H2O. The employed co-solvent was found to have different abilities to interact with the O–H and C=O moieties of 5-HMF via H-bonding and dipole-induced dipole attraction (related with the polarizability), respectively. Consequently, a high FDCA yield was achieved using three ether-type co-solvents in which these interactions are relatively weak. In a continuous-flow pattern for the base-free oxidation of 3 wt% 5-HMF solution, a FDCA yield of >98 % was achieved with 60 wt% DME/H2O under the optimized conditions.

Surface coverage can control the dispersibility of TiO2 and ZrO2 nanoparticles in hydrophobic solvents: Comparison of linear and branched ligands

Nanoparticles (NPs) can exhibit some unique properties such as dispersibility when their surfaces are modified with ligands. Unlike aqueous solvent systems, which can be described by conventional models, effective models that can describe the dispersibility of NPs in nonaqueous solvents are still controversial. In this study, phosphonate-modified metal oxide NPs were synthesized as a platform for a detailed investigation of how the ligand structure and surface coverage affect their dispersibility in hydrophobic solvents. Branched ligands were found to be more effective at reducing the saturated surface coverage than linear ligands. When the surface coverage was varied, the dispersibility of the NPs was different for the branched and linear structures, which highlights that the branched structure, an entropic ligand, provides higher dispersibility. The results contribute to further understanding of NP dispersibility in hydrophobic solvents.

Inhibitory Effects of Vernonia amygdalina Leaf Extracts on Free Radical Scavenging, Tyrosinase, and Amylase Activities.

Cytotoxicity and instability are the limitations when using bioactive compounds in cosmetic and pharmacology products. This study assesses Vernonia amygdalina leaf extracts for their antityrosinase, antiamylase, and antioxidant activities. Group A extracts were obtained using an aqueous solvent system [70% (v/v) of methanol (BTL70ME), ethanol (BTL70ET), and acetone (BTL70AC)]. Group B extracts were obtained using organic solvents of varying polarities. The results displayed that all extracts exhibited antityrosinase, antiamylase, and antioxidant activities in vitro. The most potent antityrosinase activity was observed in BTL70AC, with a half-maximal inhibitory concentration (IC50) value of 20 μg/mL. BTL_Ethyl acetate and BTL70AC showed potential antiamylase activity. BTL_Isopropanol and BTL_Ethanol exhibited potential antioxidant activity, with IC50 values of 4.0 μg/mL. The total phenolic content of BTL70ME, BTL70ET, and BTL70AC was 72.29±14.14, 65.98±11.91, and 69.37±7.72 mg gallic acid/g extract, respectively. The total flavonoid content was 53.04±5.22, 44.35±13.17, and 61.74±13.17 mg quercetin/g extract, respectively. Group A extracts contained polyphenols, flavonoids, saponins, terpenoids, steroids, and cardiac glycosides. These biological properties can potentially be attributed to the types and quantities of phytochemicals present. Bioactive compounds in the extracts may exert synergistic effects in vitro by interfering with the conformational changes of tyrosinase during substrate binding. Both groups of extracts have the potential to suppress biomolecule degradation, promote antiaging and antimelasma effects, and their phytochemicals can help lower blood glucose levels in diabetes.

Formulation Development and Evaluation of Freeze-dried Aviptadil Injection using Mannitol as Cryoprotectant

physiological effects that have been well-documented, including anti-inflammatory, immune-modulatory, anti-hypertensive, enhancement of cardiac contractility, vasodilation, and fostering immune-neuroendocrine connection. Aviptadil (AVP) is the name of the vasoactive intestinal polypeptide’s synthetic version. Aims and Objectives: The main goal of this work was to create a novel, stable, lyophilized version of aviptadil injection. The stability of aviptadil is of utmost importance due to its classification as a polypeptide, recommended storage condition of -20°C, and susceptibility to degradation in aqueous solutions. To achieve this, the aviptadil injection was processed using freeze-drying technology with the addition of mannitol, serving as a bulking and cryoprotectant agent, within an aqueous solvent system. The choice of cryoprotectant and solvent system was based on factors such as the drug substance’s solubility, stability, and feasibility in the manufacturing process. During the development of the formulation, the bulk solution underwent evaluation to assess the effects of process time, temperature, and compatibility with the materials it came into contact with. Results and Discussion: The incorporation of mannitol, a sugar alcohol, led to the stability of the bulk solution for up to 24 hours before lyophilization when stored at temperatures between 2 and 8°C. Moreover, enhanced stability was observed post freeze-drying. The lyophilization process was meticulously optimized, taking into account critical quality attributes such as description, active drug content, pH of the reconstituted solution, reconstitution time, moisture content, and color absorption percentage. The bulk solution demonstrated compatibility with various materials employed in manufacturing the drug product, such as stainless-steel vessels, polyethersulfone (PES) and polyvinylidene difluoride (PVDF) membrane filters. Notably, when the drug product bulk solution was kept refrigerated for up to 24 hours, there were no appreciable changes in the critical quality features found. The optimized freeze-dried product successfully meets the quality target product profile (QTPP)’s preset acceptance criteria. Conclusions: The stabilization of AVP injection was successfully achieved through the implementation of the lyophilization process with mannitol as the cryoprotectant. The envisaged injectable formulation proves to be safe and showcases its economic viability, convenience, and overall safety in the preparation methods. These findings strongly support the viability of the freeze-dried formulation as a technically sound solution for ensuring the stability of aviptadil as a drug substance within the freeze-dried injectable dosage form. This formulation warrants more research due to its potential to treat patients with conditions such acute respiratory distress syndrome, acute lung injury, pulmonary fibrosis, and sarcoidosis.

Exploring the solubility and solvation energetics of L-phenylalanine across diverse aqueous organic solutions at five equidistant temperatures (288.15 K to 308.15 K)

This research elucidates comprehensive insights into the dissolution nature and solvation energetics of L-phenylalanine across distinct solvent environments. Specifically, the investigation encompasses saturated solubility measurements and the subsequent derivation of overall transfer free energies (ΔGt0(i)) and entropies (ΔSt0(i)) at 298.15 K, of L-phenylalanine from an aqueous medium to aqueous solutions comprising protic ethylene glycol (EG), dipolar aprotic N,N-dimethylformamide (DMF), acetonitrile (ACN), and dimethyl sulfoxide (DMSO). In this study the 'gravimetric method' was used to find the saturated solubilities of L-phenylalanine at five equidistant temperatures (288.15 K to 308.15 K). These experimental solubility measurements serve as the foundational dataset for the subsequent determination of transfer energies. The investigated drenched or equilibrium solubility data was applied to ascertain the solvation energies. In case of pure solvent, we get the solubility trend of L-phenylalanine as follows: ACN < DMSO < DMF < EG < water, at any temperature. At 298.15 K, we found the solubilities of L- phenylalanine in pure solvents like water, EG, DMF, DMSO and ACN are 0.1675, 0.0911, 0.0888, 0.0850 and 0.0811 mol·kg−1 respectively. A pivotal facet of this study involves the examination of the correlation between the saturated solubility of L-phenylalanine and the intricate characteristics of its solvation energetics across diverse aqueous organic solvent systems.

Effects of aqueous and methanolic solvent systems on phytochemical and antioxidant extraction from two varieties of Roselle (Hibiscus sabdariffa L.) var. sabdariffa plant from Central Malawi

The extraction efficiency of aqueous and 80 % methanolic solvent systems on phytochemicals and antioxidant capacity from two varieties of Roselle (Hibiscus sabdariffa var.) was evaluated for ethno-medicinal and nutritional purposes. Phytochemical screening revealed the presence of tannins, phenols, saponins, flavonoids, cardiac glycosides and carbohydrates from both extractions. Methanolic extracts had high (P < 0.05) total phenolic compound in both red and dark red calyx H. sabdariffa, compared to aqueous extracts which ranged from 17.97 ± 0.08–258.06 ± 0.17 for dark red calyx leaf and methanolic red calyx calyces respectively. However, the study showed that red calyx H. sabdariffa had high (P < 0.05) concentration of total phenolic content compared to dark red calyx H. sabdariffa irrespective of the effect of solvent systems. In this study, aqueous extracts exhibited higher TAC than methanolic extracts but aqueous dark red calyx H. sabdariffa had high (P < 0.05) TAC compared to red calyx H. sabdariffa extracts. In methanol, red calyx H. sabdariffa exhibited high (P < 0.05) TAC compared to dark red calyx sabdariffa extracts. Anthocyanins content was high (P < 0.05) in methanol compared to aqueous extracts which ranged from 4.1562 ± 0.0742–315.460 ± 0.428 for aqueous dark red calyx fruit and dark red calyx calyces respectively. The type and polarity of solvent had a significant effect on both the quality and quantity of the extracts, phytochemicals and antioxidants of the extracts from the two H. sabdariffa varieties. The study revealed that methanolic extracts had high antioxidants, phytochemicals and anthocyanins compared to aqueous extracts. Therefore consumption and use of H. sabdariffa extracts could improve human health by either reducing or delaying the development of cell degenerative diseases like cancer and diabetes mellitus.

Effect of semicarbazide hydrochloride on the physicochemical properties of L-leucine and glycylglycine at varied temperatures and compositions

Density (ρ), sound speed (u) and viscosity (η) for an essential amino acid (L-leucine) and a peptide (diglycine) in water and (0.0496, 0.1002 and 0.1498) mol kg−1 mixed aqueous semicarbazide HCl solvent system at five distinct temperatures ranging (293.15 K – 313.15 K) and barometric pressure (101.3 kPa) have been acquired. Varied physicochemical properties like apparent molar parameters (Kϕ,s, Vϕ), hydration number (nH), partial molar parameters (K0ϕ,s, V0ϕ,), viscosity coefficients i.e. Jones Dole and Falkenhagen coefficients, transfer parameters (Vϕ,tro, Kϕ,s,tro, Btr) etc. have been enumerated from the empirically determined data. Moreover, the structure breaking (chaotropic) character of each examined protein subunit has been scrutinized through positive dBdT (temperature dependence of viscosity B-coefficient) values and negative (∂E0ϕ/∂T)p (Hepler’s constant) values. In addition, the cosphere overlap model has been used for a better understanding of assorted predominant molecular interactions in the examined solution mixtures.

Experimental and Computational Mechanisms that Govern Long-Term Stability of CO2-Adsorbed ZIF-8-Based Porous Liquids.

Porous liquids (PLs) based on the zeolitic imidazole framework ZIF-8 are attractive systems for carbon capture since the hydrophobic ZIF framework can be solvated in aqueous solvent systems without porous host degradation. However, solid ZIF-8 is known to degrade when exposed to CO2 in wet environments, and therefore the long-term stability of ZIF-8-based PLs is unknown. Through aging experiments, the long-term stability of a ZIF-8 PL formed using the water, ethylene glycol, and 2-methylimidazole solvent system was systematically examined, and the mechanisms of degradation were elucidated. The PL was found to be stable for several weeks, with no ZIF framework degradation observed after aging in N2 or air. However, for PLs aged in a CO2 atmosphere, formation of a secondary phase occurred within 1 day from the degradation of the ZIF-8 framework. From the computational and structural evaluation of the effects of CO2 on the PL solvent mixture, it was identified that the basic environment of the PL caused ethylene glycol to react with CO2 forming carbonate species. These carbonate species further react within the PL to degrade ZIF-8. The mechanisms governing this process involves a multistep pathway for PL degradation and lays out a long-term evaluation strategy of PLs for carbon capture. Additionally, it clearly demonstrates the need to examine the reactivity and aging properties of all components in these complex PL systems in order to fully assess their stabilities and lifetimes.

Energy efficient CO2 capture in dual functionalized ionic liquids and N-methyldiethanolamine solvent blend system at elevated pressures: Interaction mechanism and heat duties

In this study, three lab synthesized dual functionalized ionic liquids (DFILs) were utilized as promoters to improve the CO2 absorption performance of methyl diethanolamine (MDEA) absorbent under elevated pressures of 2–7 bar. Initially, 5 wt% DFILs containing polyamine cations (triethylenetetramine and diethylenetriamine) and cyclic amine anions (piperazine and imidazole) were blended with 20 wt% MDEA and their physical and chemical properties were examined. The pKa value at 303 K of the blend of [TETAH][Pz] + MDEA is found to be 9.83, which is nearly equal to the industrial 30 wt% monoethanolamine (MEA) solution. The CO2 absorption performance at different temperatures and pressures demonstrated that the blending of 5 wt% DFILs into aqueous MDEA significantly altered both the absorption rate and loading. The percentage loading showed a significant 22% increase in the [TETAH][Pz] promoted aqueous MDEA blend. This is attributed to the high amount of carbamate and bicarbonate formation in the DFILs blended aqueous MDEA as revealed by 13C NMR results. These results were possible due to the highly reactive piperazine anion being a crucial factor in the significant performance of the [TETAH][Pz] blend system. Further, when the regeneration heat duty of all these absorbents was calculated, it was found that MDEA and DFILs blended MDEA absorbents consumed 25.36% and 33.34–22.79% less energy than industrial MEA, respectively along with a low absorbent loss during regeneration thus, [TETAH][Pz] and [TETAH][Im] are potential promoters in an aqueous MDEA solvent system for pressurized capture of carbon dioxide.

Solubility and solvation thermodynamics of l-tryptophan in aqueous methanol solvent mixtures

This article presents mole fraction solubilities of l-tryptophan in binary aqueous methanol solvent systems and applied them to estimate thermodynamical parameters like transfer Gibbs free energetics and entropies of solutions. The estimated thermodynamic energies were linked with interaction parameters like dipole–dipole interactions, enthalpy due to transfer of l-tryptophan from water to binary water–methanol solvent mixtures. The transfer Gibbs free energetics for chemical interactions and entropies for solvent–solvent interaction were calculated by mathematical relations. The chemical transfer energetics was applied to explain the probable stability of l-tryptophan in the mixed solvents. Many associated thermophysical parameters were also calculated at standard temperature (298.15 K).