Non-aqueous Systems Research Articles

Degumming of Mulberry Silk with Papain in Non-Aqueous Systems

The nonionic reverse micelles used for degumming of mulberry silk were prepared with a non-ionic surfactant Triton X-100 (TX-100) by injecting small amount of papain aqueous solution. The weight loss of mulberry silk degummed at different concentration of papain in TX-100 reverse micelles was investigated. The effect of the amount of solubilized water was also discussed. The polarizing optic microscope was employed to observe the surface morphology of the mulberry silk. The results indicated that the weight loss of the mulberry silk was increased with increasing concentration of papain, but the W values exhibited the reverse trend. The good degumming of mulberry silk with papain was obtained in TX-100 reverse micelles. The strength of mulberry silk decreased with increasing concentration of papain.

Biochemical characterization of highly organic solvent-tolerant cutinase from Fusarium oxysporum

Abstract Biochemical characterization of cutinase from Fusarium oxysporum produced by submerged fermentation indicated that the enzyme showed a significant increase in activity, after exposure for 1 h in organic solvents, especially octanol, 2-nonanol, hexane, octane, isooctane and decane. After exposure to these solvents, the enzyme activity was higher by more than 40% when compared with the control without exposure to organic solvents. The highest activity observed in organic solvents, indicates the great potential of this enzyme in non-aqueous systems. The enzyme retained its activity almost completely in the temperature range between 28 and 50 °C, maintaining its activity more than 80% after 1 h at these temperatures. The enzyme retained its activity superior to 50% in the pH range between 5.6 and 7.0 after 24 h at 30 °C. The multivariate study showed that the activity is higher at temperature of 28 °C and pH 6.0. The enzyme has been activated in most metal ions tested, with the best result observed in the presence of Na+ (1 mM). The enzyme exhibited low activity in the ionic liquids tested (BMIM-PF4, BMIM-PF6). The presence of sodium oxalate, sodium citrate, sodium bisulfite and sodium azide (1 mM), significantly increased the activity of the enzyme, indicating that these salts bind to certain metal ions, which interfere with the action of the enzyme. The biochemical properties observed, indicating the potential of this enzyme for industrial and biotechnological applications.

ChemInform Abstract: IUPAC‐NIST Solubility Data Series. Part 90. Hydroxybenzoic Acid Derivatives in Binary and Ternary Systems. Part 2. Hydroxybenzoic Acids, Hydroxybenzoates, and Hydroxybenzoic Acid Salts in Nonaqueous Systems

AbstractReview: 46 refs.

NF in organic solvent/water mixtures: Role of preferential solvation

In comparison to well-established aqueous processes, non-aqueous processes are characterized by the increase in the number of solute–solvent–membrane interactions, which play a determining role in the understanding of solvent flux and solute rejection. Straight extension of separation mechanisms, typical of aqueous environments, to non-aqueous systems is complex, due to the significant differences in the structures and properties of the solvents. In such complex systems, competition between solute–membrane and solvent–membrane affinities may become critical. The aim of this work is to study the effect of the solute–solvent competition, in terms of relative affinity with the membrane, on the nanofiltration performance in Organic Solvent Nanofiltration. Permeation of single salts and acids (NaCl, KCl, LiCl, NaI, NaF, HCl and trifluoroacetic acid, TFA-H) in water and in organic/water mixtures through hydrophilic ceramic membranes (TiO2/Al2O3) was investigated. The effect of charge was found to affect the ion retention in water, while it was found to be less significant in the presence of organic solvents. Competition between solute and solvent in terms of preferential solvation was found to affect nanofiltration and ultrafiltration of the charged solutes. The effects of pore dimension, nature of the organic solvent and nature of anion/cation for different salts and acids are presented and discussed. Afterwards, rejections of one small organic molecule, Npys, and one model peptide, PEP1, through the same hydrophilic ceramic membranes, were studied as a function of solvent composition (%v ACN/water) and ion content (Na+, H+, Cl−, and TFA−). The roles of preferential solvation and association of chaotropic/kosmotropic ions are introduced to explain the salt effects on the rejection of the organic solutes.

Non-aqueous energy storage devices using graphene nanosheets synthesized by green route

In this paper we report the use of triethylene glycol reduced graphene oxide (TRGO) as an electrode material for non-aqueous energy storage devices such as supercapacitors and Li-ion batteries. TRGO based non–aqueous symmetric supercapacitor is constructed and shown to deliver maximum energy and power densities of 60.4 Wh kg–1 and 0.15 kW kg–1, respectively. More importantly, symmetric supercapacitor shows an extraordinary cycleability (5000 cycles) with over 80% of capacitance retention. In addition, Li-storage properties of TRGO are also evaluated in half-cell configuration (Li/TRGO) and shown to deliver a reversible capacity of∼705 mAh g–1 with good cycleability at constant current density of 37 mA g–1. This result clearly suggests that green-synthesized graphene can be effectively used as a prospective electrode material for non-aqueous energy storage systems such as Li-ion batteries and supercapacitors.

A Solid-State pH Sensor for Nonaqueous Media Including Ionic Liquids

We describe a solid state electrode structure based on a biologically derived proton-active redox center, riboflavin (RFN). The redox reaction of RFN is a pH-dependent process that requires no water. The electrode was fabricated using our previously described 'stuffing' method to entrap RFN into vapor phase polymerized poly(3,4-ethylenedioxythiophene). The electrode is shown to be capable of measuring the proton activity in the form of an effective pH over a range of different water contents including nonaqueous systems and ionic liquids (ILs). This demonstrates that the entrapment of the redox center facilitates direct electron communication with the polymer. This work provides a miniaturizable system to determine pH (effective) in nonaqueous systems as well as in ionic liquids. The ability to measure pH (effective) is an important step toward the ability to customize ILs with suitable pH (effective) for catalytic reactions and biotechnology applications such as protein preservation.

Diffusion behavior of sodium ions in Na0.44MnO2 in aqueous and non-aqueous electrolytes

The slow kinetics of bigger-sized sodium ions in intercalation compounds restricts the practical applications of sodium batteries. In this work, sodium ion intercalation/de-intercalation behavior of Na0.44MnO2 (NMO), which is one of the promising cathode materials for sodium batteries, is presented in both aqueous and non-aqueous electrolyte systems. The NMO samples synthesized using modified Pechini method shows better rate capability in 0.5 M sodium sulfate aqueous electrolyte system than the 1 M sodium perchlorate non-aqueous system. The difference in the rate performance is extensively investigated using electrochemical impedance spectroscopy (EIS) measurements and the apparent diffusion coefficients of sodium in NMO are determined to be in the range of 1.08 × 10−13 to 9.15 × 10−12 cm2 s−1 in aqueous system and in the range of 5.75 × 10−16 to 2.14 × 10−14 cm2 s−1 in non-aqueous systems. The differences in the evaluated rate capability are mainly attributed to nearly two to three orders of magnitude difference in the apparent diffusion coefficient along with the charge transfer resistance and the resistance from the formed SEI layer.

Addressing the Grand Challenges in Energy Storage

The editorial summarizes the contents of the special issue for energy storage in Advanced Functional Materials.

<b>Reactivity of the Active Chlorine of Cyanuric Chloride Immobilized on Cotton Fibers</b>

Cyanuric chloride-immobilized cotton fibers were prepared by treatment with cyanuric chloride in benzene followed by immersion with alkali. Surface characterization of the surface-modified cotton fiber was carried out by means of ATR-FTIR spectroscopy. Reactivity of active chlorine in cyanuric chloride moiety immobilized on the cotton fibers was evaluated by reaction with the amino group-containing compounds in both aqueous and non-aqueous systems. An acidic dye to the water-soluble amino group-containing compound and the alkylamines to water-insoluble amino-containing compound were used. In the aqueous system, it was found that substitution reaction of active chlorines with an amine group and the active chlorine proceeded remarkably under acidic conditions rather than under alkaline conditions. It was also suggested that two of chlorine atoms of cyanuric chloride immobilized on fibers did not exhibit stepwise sequential reaction which is common for low-molecular cyanuric chloride derivatives. Furthermore, after the reaction under acidic conditions, activity of the unreacted active chlorine is remained.This indicated that the chlorines were not consumed by a reaction with water. On the other hand, it was found that if the surface-modified fabrics were treated with different water-insoluble alkylamines, their fabrics demonstrated a good water repellency. This indicates that the active chlorine reacts with the amino group easily even in benzene. The degree of water repellency can be controlled by the alkylamine concentration in the non-aqueous media. Taking into consideration these results, it was concluded that the cotton fibers which have been treated with cyanuric chloride may be reacted sequentially with wide variety of water-soluble and/or water-insoluble amino group-containing compounds.

Update on Na-based battery materials. A growing research path

This work presents an up-to-date information on Na-based battery materials. On the one hand, it explores the feasibility of two novel energy storage systems: Na-aqueous batteries and Na–O2 technology. On the other hand, it summarises new advances on non-aqueous Na-ion systems. Although all of them can be placed under the umbrella of Na-based systems, aqueous and oxygen-based batteries are arising technologies with increasing significance in energy storage research, while non-aqueous sodium-ion technology has become one of the most important research lines in this field. These systems meet different requirements of energy storage: Na-aqueous batteries will have a determining role as a low cost and safer technology; Na–O2 systems can be the key technology to overcome the need for high energy density storage devices; and non-aqueous Na-ion batteries have application in the field of stationary energy storage.

Metal binding ability of curcumin derivatives: a theoretical vs. experimental approach

Theoretical calculations employing DFT at the B3LYP/6-311G++** level are used to investigate the tautomeric equilibrium in curcumin derivatives. The solvent effect is evaluated using the CPCM continuum solvation method. The results are compared with experimental data obtained from the X-ray crystal structure of K2A23 and UV-vis data. The KE tautomer is more stable in a vacuum and in the solid state, while in water the DK tautomer reaches a population of 90%. In agreement with spectroscopic data, theoretical calculations predict a slight prevalence of the DK form in non-aqueous solvent systems. The ability to chelate metal ions [Fe(3+), Ga(3+) and Cu(2+)] is then explored by means of (1)H, (13)C NMR and UV-Vis spectroscopy. From the calculation of the overall stability constants of metal complexes and (1)H NMR titrations with Ga(3+), it is clear that the more stable species has a 1 : 2 M/L molar ratio. The curcuminoid coordinates the metal ion through the keto-enol function in the dissociated form; in addition 2D (1)H (13)C NMR experiments suggest the involvement of carboxylic oxygen in metal coordination it was found in the solid state for the complex [Ga(K2A33)2]PF6. The rate of the complexation reaction is strongly influenced by the type of substituent on the aromatic ring of the curcuminoid (K2A33 ≈ K2A23 ≫ K2A21). In addition DPPH assay evidences how antioxidant ability of curcumin derivatives is mainly due to the presence of a phenolic group and metal coordination by a keto-enolic moiety does not affect it, especially for K2A21.

A review of current developments in non-aqueous redox flow batteries: characterization of their membranes for design perspective

The non-aqueous redox flow battery (RFB) is one of the emerging large-scale energy storage systems that may overcome the low energy density limited by breakdown of water at a high voltage in aqueous RFBs. Yet development of the non-aqueous RFB is at an early stage, so its components are not thoroughly understood. As a key component of non-aqueous RFBs, the role of the membrane is to suppress cross-contamination between the anolyte and catholyte confined in two separate compartments, and to transport the charge carrier ions selectively for the completion of the circuit during cell operation. In this review, recent studies on non-aqueous redox flow systems are summarized including redox couples, electrolytes, and systems including membranes. A focus is placed on comparison of battery performance in terms of the current and power density through membranes. In addition, we introduce syntheses and characterization of membranes used for non-aqueous RFBs.

Particle-stabilised non-aqueous systems

We have prepared various non-aqueous systems of emulsions, foams, liquid marbles and polymeric materials stabilised solely by either dichlorodimethylsilane (DCDMS)-modified amorphous silica or organo-modified Laponite clay nanoparticles.

Network Formation in Various Dispersing Medium of Hydrophobic Colloidal Silicon Dioxide

Colloidal silicon dioxide is a fine amorphous powder consisting of particles about 7-40 nm in size. This study utilized hydrophobic colloidal silicon dioxide, aerosil R 972, as gelling agent in non-aqueous systems. Aerosil R 972 could convert light mineral oil and Luvitol EHO® into gel at concentrations of 7 and 10% by weight, respectively. The appearance of the systems prepared from polyethylene glycol 400, 600 and light mineral oil was clear, but the others were turbid. There was no phase separation or color changes of the systems after temperature change of 6 cycles. The obtained gel exhibited very little change of pH and viscosity after stability testing. After aerosil R 972 was incorporated into the mixed media with different dielectric constant, all systems showed the decrease of a viscosity, especially, the formulations having low dielectric constant. The addition of aerosil R 972 into dispersing medium with higher dielectric constant provided higher viscosity of the system because of the mismatch of the polarity between particles and dispersing media. In case of the incorporation of aerosil R 972 into mixed media, the rank order of viscosity was PEG 400–glycerin> PEG 400–PG > PEG 400–water. All of PEG 400–glycerin mixtures were obviously converted into gel, while only PEG was not converted with aerosil R 972 addition.

Stability of zircon pigments in water and diethylene glycol media: The case of turquoise V–ZrSiO4

The stability of pigment particles can be affected by physico-chemical interactions between the pigment particles and a solvent. In this study, the surface charges and stabilities of blue V–ZrSiO4 pigments in aqueous (water) and non-aqueous (diethylene glycol) suspensions were investigated. As a function of pH, the isoelectric points (IEP) for the commercial and synthesised pigments were determined to be 2.2 and 1.7, respectively. ICP-OES results show that the cations of V–ZrSiO4 pigments dissolve in both aqueous and non-aqueous systems. The dissolution of the pigment particles was more significant in DEG because the total ion concentration (>2000ppm) was higher than that of the aqueous medium (>200ppm). The colour stability of the V–ZrSiO4 powder deteriorates as a consequence of an insufficient chemical stability both in the water and DEG media. Additionally, the V–ZrSiO4 particles dissolve with proton-promoted and hydroxyl-promoted dissolution mechanisms in the aqueous medium, whereas these particles dissolve with a ligand-promoted dissolution mechanism in the non-aqueous medium.

Response of organic liquid scintillators to fast neutrons and gamma radiation

Liquid organic scintillators are cocktails of aromatic fluorophores in an aromatic solvent. They find widespread use in Liquid Scintillation Counters with applications in medical diagnostics as well as fundamental nuclear and particle physics. Ultima Gold™ XR, a commercially available organic liquid scintillator from Perkin Elmer, can be used in both aqueous and non-aqueous systems and is typically used for beta detection in medical diagnostics. Its performance under gamma radiation and neutron radiation is less well-characterized.Special and normal Ultima Gold™ XR liquid scintillators were exposed in separate experiments to fast neutrons and high energy photons from a nuclear reactor and to gamma rays from a Co-60 source. To perform the measurements in the radiation chamber, a custom light collection system consisting of a fiber optic cable, spectrometer and a diffuse reflecting optical cavity was fabricated. Advanced calibration procedures, traceable to NIST standards, were developed to determine photon fluxes and flux densities of the scintillators under ionizing radiation conditions. The scintillator emission spectra under gamma radiation from a Co-60 source and neutron radiation from a pool-type nuclear reactor were recorded and compared. Results on the spectrometer design and comparison of the spectra under different exposure are presented.

Adsorption Study of Reactive Dyes on Cotton Fabric in Non-Aqueous Systems

Abstract: The non-ionic reverse micelles used for dyeing cotton fabric were prepared with a non-ionic surfactant Triton X-100 (TX-100) by injecting small amount of reactive dye aqueous solution. The effect of electrolyte on the adsorption capacity of reactive dyes onto cotton fabric in this system was studied. And the adsorption properties of three water-soluble anionic azo dyes including Reactive Blue 222, Reactive Red 195 and Reactive Yellow 145 onto cotton fabric in TX-100 reverse micelle were also studied and compared. The results indicated that reactive dyes showed a better adsorption property on cotton fabric in TX-100 reverse micelle without the addition of NaCl. The adsorption of the dyes onto cotton showed better agreement with Langmuir isotherm equation. Reactive Yellow 145 with lower negative charge and higher hydrophilicity exhibited the higher adsorption capacity than the other dyes. The adsorption process follows by the chemical adsorption.

Enthalpies and heat capacities of interaction of tetraalkylammonium bromides with hexamethylphosphoric triamide in water, methanol and ethylene glycol: The comparative analysis of aqueous and non-aqueous systems

This paper focuses on the interaction between familiar hydrophobic solutes – tetraalkylammonium ions and hexamethylphosphoric triamide (HMPT) in water and H-bonded non-aqueous solvents such as methanol (MeOH) and ethylene glycol (C2H4(OH)2). Enthalpic and heat capacity parameters of electrolyte–amide and methylene group–amide pair interaction have been extracted from the enthalpies of solution for Et4NBr and Bu4NBr in the mixtures of MeOH or C2H4(OH)2 with HMPT at 298 and 313K and compared with those in water. We have found that for tetraalkylammonium ions of moderate size solvophobic interaction with apolar groups of HMPT molecule is much weaker pronounced in non-aqueous media than in water.

Activity coefficients from Gibbs adsorption equation

A new thermodynamic equation derived from the integration of Gibbs adsorption equation for binary systems at the vicinity of the surface saturation region is presented. The equation, attached to a given solution model for describing the dependency on bulk composition of the solute activity coefficient, allows for the determination of the constants of the solution model and therefore for the activity coefficients by means of a nonlinear fitting of surface tension data. The model was tested for 19 aqueous binary systems at 298.15K or 303.15K, including alcohols, glycols, alkanolamines, carboxylic acids, acetone, and 1,4-dioxane, and for 5 non-aqueous systems with hexane or heptane plus ethanol or 1-propanol, and cyclohexane plus isooctane. The comparison of the infinite dilution activity coefficients with those obtained from a previously reported bulk-surface equilibrium model in which Volmer's surface equation of state is used, and with activity coefficients reported in the literature determined from liquid–vapor equilibrium, shows an improvement in the determination of activity coefficients from surface tension data.

Corrosion-Resistant Electrochemical Platings on Magnesium Alloys: A State-of-the-Art Review

Industrial deployment of magnesium alloys in most instances requires anti-corrosion coatings. Distinct from conversion coatings, the electro/electroless plating techniques are emerging as the common means of coating magnesium; however, more research is needed. A state-of-the-art review was undertaken with respect to aqueous plating systems (including pretreatment, under-coating, and electroplating), electroless plating (being treated individually, though it is used as undercoating for subsequent plating in some cases), non-aqueous plating systems (including high-temperature molten salts and ionic liquids), and novel plating methods. In addition to the performance assessment of various plated coatings on magnesium alloys, merits and demerits of existing plating techniques are discussed. Based on the literature to date, the practical issues faced in magnesium plating are raised, and possible advances discussed, providing some instructive guidelines for future work.