Acetone-water Solvent Research Articles

Tannin characterization and sourcing in historical leathers through FTIR spectroscopy and PCA analysis

This study aimed to identify and classify the type of plants used for tanning historical leathers using cost-effective Fourier transform infrared (FTIR) spectroscopy. The investigation was carried out on five plants (oak bark, sumac, valonia, tara, and gallnut) and four historical leather samples from book bindings dating back to the Qajar period. Tannin extraction from both plants and leathers was performed using acetone–water solvent, and the samples were then subjected to FTIR spectroscopy. Pre-processing of the spectra included baseline correction, smoothing, and normalization. Principal component analysis (PCA) was used to identify the source of tannins based on FTIR results. FTIR was found to provide a good separation of condensed tannins from hydrolysable ones. However, PCA analysis allowed for the separation and identification of the type of plant used for tannin extraction. The examination of historical leather samples revealed that the primary classification based on the type of tannin is possible, but accurate identification faces challenges due to structural changes and degradation over time.Graphical abstract

Computational investigation of explicit solvent effects and specific interactions of hydroxypyrene photoacids in acetone, DMSO, and water.

This work employs the correlated wavefunction-based methods ADC(2) and CC2 in combination with the implicit solvent model COSMO to calculate the UV/Vis absorption and fluorescence emission energies of particularly strong hydroxypyrene photoacids in acetone. According to the Förster cycle, the electronic transition energies are first used to compute , i.e., the pKa change upon excitation and then the excited-state pKa (labeled ) with ground-state pKa values based on COSMO-RS as additional inputs. Furthermore, for the strongest photoacid of that class, namely tris(1,1,1,3,3,3-hexafluoropropan-2-yl)-8-hydroxypyrene-1,3,6-trisulfonate, the need to go beyond implicit solvation and to account for explicit solvent effects on the electronic transition energies and the resulting ΔpKa is investigated in the solvents acetone, dimethyl sulfoxide (DMSO), and water. For this, a hybrid implicit-explicit approach is followed by comparing micro-solvated structures that are generated based on Kamlet-Taft considerations. While implicit solvent effects are mostly sufficient for the aprotic solvent acetone, one explicit solvent molecule seems relevant for DMSO due to its stronger hydrogen-bond (HB) acceptance and hence larger interaction with the photoacid OH group as a HB donor. For the protic solvent water, the situation is more complicated, involving at least one water molecule at the OH group and up to three water molecules at the O- group of the corresponding base. Finally, these results are used to rationalize the experimentally observed spectral evolution of the photoacid absorption band in acetone-water solvent mixtures.

Feasibility Assessment of the Identification of the Source of Condensed Tannins in Leathers by FTIR Spectroscopy and Chemometrics

This study aimed to investigate the feasibility of identifying the type of plant used in the tanning of leathers by cost-effective Fourier transform infrared (FTIR) spectroscopy. The investigation was performed on European horse-chestnut (fruit peel), mimosa, and quebracho and three specimens of mimosa-tanned leathers. Tannin extraction from plants was performed in an ultrasonic bath using acetone-water solvent (70%). Tannin extraction from leathers was carried out from the corium fibers using acetone-water solvent (1:1). After extraction, filtration, centrifugation, and solvent removal, the samples were subjected to FTIR spectroscopy. Principal Component Analysis (PCA) and hierarchical clustering were used to identify the source of tannins based on FTIR results. In addition to FTIR spectra, their first and second derivatives were also used in statistical analyses. The obtained FTIR spectra and their derivatives and the results of PCA and hierarchical clustering showed that rich plant sources of condensed tannins can be well differentiated by spectroscopy in the fingerprint region (700-1800cm-1). The PC1-PC2 plot in the analysis of FTIR spectra and the PC2-PC3 plot in the analysis of derivatives showed the best ability to differentiate and identify the extracts. Multivariate PCA and cluster analyses performed well in identifying the type of plant used in the tanning of the studied leathers, especially when applied to the derivatives of FTIR spectra.

Insights into pathways and solvent effects of fructose dehydration to 5-hydroxymethylfurfural in acetone–water solvent

Preparation of 5-hydroxymethylfurfural (HMF) from fructose is a typical liquid-phase biomass conversion reaction, strongly affected by solvent media and acid catalysts, including fructose reactivity and HMF selectivity. Most works on solvent selection were conducted experimentally, however, lack of theoretical guidance. Herein, we applied experimental and theoretical techniques to investigate solvent effects of acetone–water solvent on HMF production. Factors including product distribution, key intermediate and byproduct identification, reaction pathways, and solvation simulation of solutes were systematically evaluated. The results indicate that water ensures high substrate concentration and assists intermolecular hydrogen transfer to accelerate reaction rate. Various HMF degradation reactions are introduced in the presence of water, however, are significantly inhibited by acetone. Moreover, acetone increases the population of high-reactive fructofuranose isomers, thus improving HMF yield. Therefore, water and acetone play a synergistic role in HMF preparation. Also, our findings provide theoretical insights for solvent selection and methodology for studying solvent effects.

Experiments and Kinetic Modeling of Fructose Dehydration to 5-Hydroxymethylfurfural with Hydrochloric Acid in Acetone–Water Solvent

Experiments and Kinetic Modeling of Fructose Dehydration to 5-Hydroxymethylfurfural with Hydrochloric Acid in Acetone–Water Solvent

Efficient One-Pot Production of 5-Hydroxymethylfurfural from Glucose in an Acetone–Water Solvent

Efficient One-Pot Production of 5-Hydroxymethylfurfural from Glucose in an Acetone–Water Solvent

An Organic Solvent-Free Method for the Extraction of Ellagic Acid Compounds from Raspberry Wine Pomace with Assistance of Sodium Bicarbonate.

Industrial processing of raspberry juice and wine generates considerable byproducts of raspberry pomace. Ellagic acids/ellagitannins, being characterized by their antioxidant and antiproliferation properties, constitute the majority of polyphenolics in the pomace and are valuable for recovery. In the present study, we developed a novel procedure with sodium bicarbonate assisted extraction (SBAE) to recover ellagic acid from raspberry wine pomace. Key parameters in the procedure, i.e., sodium bicarbonate concentration, temperature, time and solid/liquid (S/L) ratio, were investigated by single factor analysis and optimized subsequently by Response Surface Methodology (RSM). Optimal parameters for the SBAE method here were found to be 1.2% (w/v) NaHCO3, 1:93 (w/v) S/L ratio, 22 min and 100 °C. Under these conditions, the ellagic acid yield was 6.30 ± 0.92 mg/g pomace with an antioxidant activity of 79.0 ± 0.96 μmol Trolox eq/g pomace (DPPH assay), which are 2.37 and 1.32 times the values obtained by extraction with methanol–acetone–water solvent, respectively. The considerable improvement in ellagic acid extraction efficiency could be highly attributed to the reactions of lipid saponification and ellagitannin hydrolysis resulted from sodium bicarbonates. The present study has established an organic solvent-free method for the extraction of ellagic acid from raspberry wine pomace, which is feasible and practical in nutraceutical applications.

Improvement of mechanical properties and water resistance of bio-based thermal insulation material via silane treatment

Buildings, whether commercial or residential, consume a huge proportion of the energy produced globally to maintain livable conditions within their walls. It is estimated that 40% of the energy produced is devoted for buildings, which represents around 30% of global CO2 emissions. Most of buildings are equipped with heat insulation materials to reduce the energy loss and help in maintaining the desired conditions. However, most of these heat insulators are derived from fossil fuel or have environmental and safety concerns. Herein, the effect of two different silane treatments on enhancing the compatibility between date palm wood fibers (DPWF) and polylactic acid (PLA) to produce green biodegradable composites was investigated. The composites were fabricated for the use of heat insulation panels in construction, with filler percentage ranging from 0 to 40 wt%. To the best of our knowledge, this is the first work that examines silane treatment on PLA-wood composites in heat insulation for construction and buildings. The DPWFs were treated with aminopropyl triethoxysilane (APTES) using two different solvents: acetone-water solvent mixture (SA), and ethanol-water solvent mixture (SE). The composites were examined to evaluate the effect of treatments on the physical, thermal, and mechanical properties. Furthermore, the composite structure was characterized by FTIR and SEM techniques. The mechanical properties and water resistance of treated composites showed tremendous improvements compared to untreated composites (PLA-UTDPWF). The 20 wt% composites tensile strength increased from 8.6 MPa for PLA-UTDPWF, to 16.5 and 22.4 MPa for PLA-SA and PLA-SE composites, respectively. Nevertheless, the thermal conductivity slightly increased upon fibers treatment, but remained in a low range of values that are appropriate for heat insulation, varying from 0.085 to 0.105 W/(m⋅K). Overall, the SE treatment achieved the best improvements by enhancing preferred features such as the mechanical strength and minimizing undesirable features such as water retention, while maintaining low thermal conductivity. The treatments helped in producing clean and biodegradable heat insulations.

Effect of Mixed Water–Acetone Solvent on the Stability of Copper(II) Glycylglycinate Complexes

Potentiometric titration at a temperature of 298 K and ionic strength of solutions of 0.1 (NaClO4) is used to determine the stability constants of normal and deprotonated mono- and bis-glycylglycinate copper(II) complexes in a water–acetone solvent of variable composition. The peptide group dissociation constants of the glycylglycinate copper(II) complex in water–acetone mixtures are calculated using the obtained data. It is found that the stability of all complexes of copper(II) with glycylglycinate ion increases along with the concentration of acetone in the solution. The contributions from the resolvation of reagents in a water–acetone solvent to the change in the Gibbs energy of the formation of copper(II) glycylglycinate are estimated. It is established that the growth of the stability constant of the glycylglycinate copper(II) complex in an aqueous-acetone solution is determined by the weakening of ligand solvation. The results are compared to similar data for the complexation reactions of the glycylglycinate ion with copper(II) and nickel(II) ions in aqueous solutions of ethanol and dimethylsulfoxide.

Ternary phase diagrams and metastable zone width of azithromycin in water–acetone solvent mixtures

The transition water activity of azithromycin in water–acetone solvent mixtures at temperatures 293.15 K, 298.15 K, 303.15 K and 308.15 K was determined under atmospheric pressure, and the ternary phase diagrams for the system of water–azithromycin–acetone at varying temperature were described. Results showed that azithromycin monohydrate can be obtained by lowering the water activity and the transition water activity in acetone–water solvent mixtures at temperatures (293.15 K, 298.15 K, 303.15 K and 308.15 K) was 0.17, 0.21, 0.242 and 0.287, which increased with temperature. Besides, the metastable zone width (MSZW) of azithromycin dihydrate in water–acetone solvent mixtures was measured by laser method. The effect of initial temperature and cooling rate on MSZW of azithromycin dihydrate was studied. It was observed that the MSZW decreases with the increase in initial temperature. Nevertheless, the MSZW becomes wider by enhancing the cooling rate. All the results are of great importance to develop a crystallization process for manufacturing azithromycin hydrate and could be helpful to other solvate transformation research.

A heterometallic Cd/Ag/Se complex incorporating 3-ferrocenyl-5-(2-pyridyl)pyrazolato (fcpp) ligands: synthesis and structure of [Cd2{Ag(SePh)}2(μ3-OH2)2(μ2,η3-fcpp)4]·2C3H6O

Abstract A self-assembly reaction of Cd(NO3)2 · 4H2O, 3-ferrocenyl-5-(2-pyridyl)-pyrazole (Hfcpp), [Ag(SePh)] n , and Et3N in a mixed acetone-water solvent resulted in the formation of a heterometallic complex [Cd2{Ag(SePh)}2 (μ 3-OH2)2(μ 2,η 3-fcpp)4] · 2C3H6O (1) with a phenylselenolate ligand. The two cadmium and two silver centers are linked by four [μ 2,η 3-fcpp]− ligands and two μ 3-OH2 water molecules. Each Cd atom is in a slightly distorted octahedral coordination environment, while each Ag atom shows a distorted tetrahedral coordination geometry, which is composed of two pyrazolyl nitrogen atoms, one selenium atom, and one oxygen atom.

Enthalpies of Glycine Protonation in Water–Acetone and Water–Ethanol Solvents

Heat effects of the reaction of glycine protonation at 298 K in water–ethanol (µ = 0.1 (NaClO4)) and water–acetone (µ = 0.3 (NaClO4)) solvents of various compositions are determined via calorimetry. The enthalpies of the resolvation of glycinium ions in aqueous solutions of ethanol and acetone are calculated using the literature data. It is established that a minor change in the heat effect of the reaction of glycine protonation in water–ethanol and water–acetone solvents is associated with the mutual compensation of the enthalpies of proton, glycinium-ion, and glycine resolvation in these media. It is shown that the contribution from the enthalpy component to the change in the Gibbs energy of this reaction is insignificant.

Designer poly(urea-siloxane) microspheres with controlled modulus and size: Synthesis, morphology, and nanoscale stiffness by AFM

Crosslinked poly(urea-siloxane) (PUS) copolymer microspheres with diameters ranging from 0.8 to 1.8 μm with diameter polydispersity indices between 1.15 and 1.60 were synthesized in one-step precipitation polymerization in water-acetone solvent mixtures at room temperature. The spheres were obtained using aminopropyl-terminated siloxanes, isophorone diisocyanate and a tetrafunctional isocyanate crosslinker, employing a systematically varied molar ratio. The length of the siloxanes was controlled to obtain spheres with pre-determined Young's modulus values. Phase separation between soft disiloxane/poly(dimethylsiloxane) segments and hard isophorone bisurea units was observed with an excellent spatial resolution of ∼5 nm using atomic force microscopy (AFM). AFM mapping of the Young's modulus was achieved utilizing the PeakForce Quantitative Nanomechanical Mapping (QNM) mode. This AFM method allowed us to also measure the values of elasticity moduli of individual microspheres, ranging from 200 to 900 MPa. The microspheres can be used as filler to fine-tune the properties of composite materials, particularly with regard to elasticity. The hydrophobicity was also varied as indicated by water contact angle values between 122° - 132°. These features open the possibility of preparing designer composites for a range of applications from coatings to the biomedical field.

Optimization study of polyethylene glycol and solvent system for gas permeation membranes

Cellulose acetate (CA) membranes blended with Polyethylene glycol (PEG) in acetone–water solvent system were synthesized by using solution-casting method that resulted in the formation of flexible, white membranes. Different molecular weight (MW) grades of PEG (including MW 1000, 10,000 and 20,000 g/mol) were used. Cast membranes were tested for tensile strength and permeability at different loading of PEG MW 10,000 and 20,000 g/mol. Excellent flexible membranes were produced in acetone–water solvent system in the presence of PEG, which were otherwise brittle. Surface structure and morphology were analysed using scanning electron microscopy. The presence of different functional groups was confirmed using Fourier transform infra-red spectroscopy and the mechanical characteristics were studied by tensile testing. The introduction of PEG caused an increase in permeability of the membranes. The increase in permeability is due to the opening up of pores as the membrane becomes more flexible, when the plasticizer is added. The permeability continues to increase with the addition of PEG. Moreover, the resulting membranes are not only more flexible, but also have largely improved tensile strength as compared to the CA membranes without PEG. This improved tensile strength can also be attributed to the improved flexibility of the membrane. A trade-off is reached between tensile strength and permeability as increasing amount of PEG improves tensile strength but the resulting membrane becomes too permeable to be used for gas separation. Moreover, using PEG of higher MW resulted in porous membranes, even at low amounts of PEG. Therefore, we concluded that CA membrane with less amount of low-MW PEG (i.e. 5% PEG of MW 1000 g/mol) must be used to optimize both permeability and tensile strength of the membrane.

Salt-Induced Swelling and Volume Phase Transition of Polyelectrolyte Gels

A theoretical model of polyelectrolyte gels is presented to study continuous and discontinuous volume phase transitions induced by changing salt concentration in the external solution. Phase diagrams are constructed in terms of the polymer–solvent interaction parameters, external salt concentration, and concentration of fixed charges. Comparisons with previous experiments for an ionized acrylamide gel in mixed water–acetone solvents are made with good quantitative agreement for a monovalent salt (NaCl) but fair qualitative agreement for a divalent salt (MgCl2), using a simple set of parameters for both cases. The effective polymer–solvent interactions vary with the volume fraction of acetone in the mixed solvent, leading to either continuous or discontinuous volume transitions. The presence of divalent ions (Mg2+) in addition to monovalent ions in the external solution reduces the critical salt concentration for the discontinuous transition by several orders of magnitude. Moreover, a secondary continuous transition is predicted between two highly swollen states for the case of a divalent salt. The present model may be further extended to study volume phase transitions of polyelectrolyte gels in response to other stimuli such as temperature, pH and electrical field.

Techno-economic assessment of poly-3-hydroxybutyrate (PHB) production from methane—The case for thermophilic bioprocessing

A major obstacle preventing the large scale production of polyhydroxyalkanoates (PHAs) has been the lack of a reliable, low cost, large volume feedstock. The abundance and relatively low price of methane therefore marks it as a substrate of interest. This paper presents a techno-economic assessment of the production of poly-3-hydroxybutyrate (PHB) from methane. ASPEN Plus was used for process design and simulation. The design and economic evaluation is presented for production of 100,000t/a PHB through methanotrophic fermentation and acetone-water solvent extraction. Production costs were estimated at $4.1–$6.8/kg PHA, which compares against a median price of $7.5/kg from other studies. Raw material costs are reduced from 30 to 50% of production for sugar feedstocks, to 22% of production for methane. A feature of the work is the revelation that heat removal from the two-stage bioreactor process contributes 28% of the operating cost. Thermophilic methanotrophs could allow the use of cooling water instead of refrigerant, reducing production costs to $3.2–5.4/kg PHA; it is noted that PHB producing thermophilic methanotrophs are yet to be isolated. Energy consumption for air compression and biomass drying were also identified as significant capital and operating costs and therefore optimisation of bioreactor height and pressure and biomass moisture content should be considered in future research.

The solubility of cefquinome sulfate in pure and mixed solvents

Solid-liquid equilibrium data of cefquinome sulfate is important to develop industrial crystallization processes for cefquinome sulfate. The solubilities of cefquinome sulfate in five pure solvents (methanol, ethanol, ethylene glycol, acetic acid and water) from 277.15 to 305.15 K and in a binary acetone-water solvent from 278.15 to 293.15 K were measured at atmospheric pressure. The pure-solvent solubility data was correlated to the modified Apelblat and Van’t Hoff equations whereas the mixed-solvent system data was correlated to the modified Apelblat, Van’t Hoff, CNIBS/R-K and Jouyban- Acree models. It was found that the solubilities of cefquinome sulfate in all tested solvents decreased with the increasing of temperature. In addition, the thermodynamic properties of the dissolution processes, including standard Gibbs free energy, enthalpy and entropy changes, were calculated using the Van’t Hoff equation. It was found that the dissolution of cefquinome sulfate is exothermic.

Extraction, optimisation and characterisation of phenolics from Thymus vulgaris L.: phenolic content and profiles in relation to antioxidant, antidiabetic and antihypertensive properties

SummaryThe objectives of this study were to examine varying extraction conditions of Thymus vulgaris L. as related to phenolic content and profiles of the extracts and their antioxidant, antihypertensive and antidiabetic properties. Phenolics were extracted under various conditions pertaining to free and bound phenolics, solvent type and combination of extraction time and temperature, and these extracts were evaluated in terms of their antioxidant activities and inhibitory activities of angiotensin‐converting enzyme (ACE), α‐glucosidase and α‐amylase. The acetone–water solvent mixture (1:1; v/v) produced the extract with the greatest phenolic content, antioxidant activity and inhibitory activities of ACE and α‐glucosidase. The optimal extraction temperature for maximum phenolic content and antioxidant activity associated with methanol extraction was 60 °C, whereas a lower temperature at 40 °C was required to maximise inhibitory activities for ACE, α‐glucosidase and α‐amylase. An inverse relationship was seen between antioxidant and glucosidase inhibitory activities vs. the ACE and α‐amylase inhibitory activities, which suggests the need for extractions to be directed to specific bioactivities of thyme extracts. Generally, the results indicate major differences in phenolic profiles among the tested extraction conditions with thymol as the predominant phenolic seen in most extractions, while gallic acid, rosmarinic acid or diosmin also predominated in other extracts. Extracts with the same predominant phenolic compound and similar phenolic content showed major disparities in their ACE, glucosidase and α‐amylase inhibitory activities, indicating that the major phenolic profiles of thyme extracts may not be necessarily related to the degree of inhibition of ACE, glucosidase and α‐amylase enzymes.

Enhanced separator properties by coating alumina nanoparticles with poly(2-acrylamido-2-methyl-1-propanesulfonic acid) binder for lithium-ion batteries

To enhance thermal stability and high-rate capability of lithium-ion batteries, both sides of porous polyethylene (PE) and poly(vinylidene fluoride) (PVdF) separators are coated with nanosized Al2O3 powder and poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) binder dispersed in acetone-water solvent. For comparison, PVdF is also used as a polymer binder for coating. The Al2O3/PAMPS-coated separators show an improved thermal shrinkage resistance at 120 °C and enhanced electrochemical performance of LiCoO2‖graphite full-cell. These improvements are due to the binding ability of PAMPS, the large surface area of the Al2O3 nanoparticles, and their surface hydrophilicity maintained by the PAMPS binder to exhibit outstanding wettability towards the electrolyte, resulting in the increase in discharge capacity and high-rate capability.

Immobilized Horseradish Peroxidase (I-HRP) as Biocatalyst for Oxidative Polymerization of 2,6-Dimethylphenol

An enzyme, horseradish peroxidase (HRP), was immobilized on silica nanorods and employed as a catalyst for the oxidative polymerization of 2,6-dimethylphenol. With this catalytic system, the polymer, poly(2,6-dimethyl-1,4-phenylene oxide), was successfully obtained from a water–acetone solvent system. The immobilized HRP exhibited substantially enhanced enzymatic activity toward oxidative polymerization as well as some degree of reusability compared with free HRP.