Non-aqueous Media Research Articles

Nanocomposites Produced with the Addition of Carbon Nanotubes Dispersed on the Surface of Cement Particles Using Different Non-Aqueous Media

The inclusion of carbon nanotubes (CNTs) in cementitious composites has been studied due to their electrical, thermal, and mechanical enhancing properties. Considering the hydrophobic characteristics of CNTs, these nanomaterials need to be well dispersed in the aqueous media in which they are inserted to guarantee those gains. Among the methods applied to produce such composites is the dispersion of CNTs on the surface of anhydrous cement particles using non-aqueous suspensions such as acetone, ethanol, or isopropanol. Even though those non-aqueous media have been individually studied by researchers, comparisons of the efficiency of CNTs dispersion was not found in the literature. Therefore, as a novelty, the present article aims to analyze the influence of the addition of the multi-walled CNTs dispersed in the cited three types of non-aqueous suspensions on the cement paste’s electrical and mechanical properties. Pastes containing 0%, 0.5%, and 1.0% of CNTs were prepared on the surface of anhydrous cement particles using a pre-dispersion technique based on simultaneous sonication and mechanical agitation in the three cited media. Tests to determine electric-volumetric resistivity, compressive strength, and splitting tensile strength were performed. It was observed that acetone dispersion decreases the cement paste’s electrical resistivity, even without the addition of CNTs. The cementitious composites with CNTs demonstrated increased mechanical strength (both compressive and tensile) using all three dispersion media. Statistical analysis (analysis of variance—ANOVA—and Tukey’s Test) was performed to evaluate the significance of the results.

Revisiting Electrocatalytic CO2 Reduction in Nonaqueous Media: Promoting CO2 Recycling in Organic Molecules by Controlling H2 Evolution

Electrochemical CO2 reduction to fuels or commodity chemicals using renewable energy has drawn attention as a strategy for closing the anthropogenic chemical carbon cycle. More than that, enhancing the C–C coupling between the intermediates could lead to producing a range of high‐value multi‐carbon molecules. Although the research mainly focuses on the aqueous media for the electrochemical CO2 reduction reaction (eRRCO2), using nonaqueous electrolytes has the advantage of suppressing the hydrogen evolution reaction, controlling the proton‐assisted reduction reactions, and favoring the C–C coupling. Herein, the use of nonaqueous electrolytes for eRRCO2 and the components of the electrochemical reactor that affect the selectivity of the reaction are revisited. This review provides a perspective view of recent findings compared to well‐established papers while presenting what is known about eRRCO2 in nonaqueous media.

An approach to enhanced redispersibility of cellulose nanocrystals via freeze-drying their Pickering emulsions

To enhance the redispersibility of dried nanocellulose, cellulose nanocrystal (CNC) cryogels were produced by freeze-drying CNC-stabilized cyclohexane-in-water Pickering emulsions. The CNC cryogels were easily redispersed in water and organic solvents; thus, the approach proposed made it possible to significantly improve CNC redispersibility in aqueous and nonaqueous media.

Adsorption of Reactive Red 120 in Decamethyl-Cyclopentasiloxane Non-Aqueous Dyeing System

Traditional dyeing usually consumes a significant amount of water and salts, thus causing environmental pollution. Salt-free and low-water dyeing has become an important research direction in the cotton fabric dyeing industry. The non-aqueous media dyeing technology, using decamethylcyclopentasiloxane (D5) as the dyeing medium, has achieved energy saving and emission reduction in this industry. To investigate the influence of inorganic salts on the dyeing properties of reactive dyes in a non-aqueous medium dyeing system, the adsorption kinetics and level dyeing property of C.I. Reactive Red 120 were investigated at various concentrations of sodium sulfate. When no salts were included in the siloxane non-aqueous dyeing system, 80% of the reactive dye could diffuse onto the cotton fabric surface after 10 min. However, if 13% salts were added during dyeing, 87% of the reactive dye could diffuse to cotton fabric surface over the same amount of time. Moreover, the adsorption rate of dye was increased from 3.85 mg/g·min to 5.04 mg/g·min when the quantity of salts was increased from 0% to 13%. However, the concentration of sodium sulfate had minimal effect on the color depth of the dyed fabric and the final uptake of dye. But, when the concentration of sodium sulfate was significant, the level dyeing property of the dye became poor as the Sγ(λ) value was increased from 0.020 to 0.042. The adsorption kinetic of C.I. Reactive Red 120 in D5 dyeing solution may be best described by the pseudo-second-order kinetic model. As the sodium sulfate concentration increases, the half-dyeing time gradually decreases and the adsorption rate of dye increases. The repulsive force between the dye and the cotton fiber was lowered by the addition of sodium sulfate. Consequently, in the D5 dyeing system, the level dyeing property of reactive dye may be affected by the adsorption rate. Therefore, the formula of reactive dyes that do not contain salts can be applied successfully in non-aqueous dyeing systems.

Salidroside synthesis via glycosylation by β-D-glucosidase immobilized on chitosan microspheres in deep eutectic solvents

This study aimed to establish a novel method for catalysing salidroside synthesis by immobilized β-D-glucosidase with deep eutectic solvents (DESs) as a new green non-aqueous medium. To this end, the catalytic properties of β-D-glucosidase (i.e. activity, stability, and enzymatic properties) were analysed within sixteen different DESs systems. Although most DESs significantly improved enzyme stability, they also reduced enzymatic activity. This was verified at the molecular level by employing fluorescence spectroscopy to evaluate conformational changes in β-D-glucosidase molecules. Subsequently, chitosan microspheres were used to immobilize β-D-glucosidase; the structures of the microspheres and immobilized enzyme were observed by scanning electron microscopy (SEM). Through single factor experiments and application of a response surface design, the optimal conditions for production of salidroside by the reaction of tyrosol with immobilized β-D-glucosidase were established. These conditions comprised 80 vol% ChCl/G (1:2), 50 °C reaction temperature, 5.8 pH, 100 h reaction time, 45 U/mL enzyme dosage, and a tyrosol/D-glucose molar ratio of 10. Under these conditions, the average conversion rate of the tyrosol substrate was 31.6%. Moreover, a salidroside crude product was obtained with a purity >70% (g/g) and a substrate conversion rate of immobilized β-D-glucosidase >50% of its initial value after five repeated uses. Collectively, this study establishes a novel green reaction system for the efficient preparation of salidroside and other glycoside compounds, while also providing a theoretical foundation for the analysis of β-D-glucosidase catalytic reactions in DESs systems.

Applicability of a synthesized melamine based covalent organic framework as a novel ionophore for the potentiometric determination of mercury (II): Computational and experimental studies

In this research, the complexation of a recently synthesized covalent organic framework (schiff base network1) with 10 different cations was investigated by QTAIM (quantum theory of atoms in molecules) computations. The theoretical results showed the schiff base network1 interactions with Hg2+ is considerably stronger than other cations and it can be used as an selective ionophore for the development of a potentiometric sensor to determination of Hg2+. Therefore, a Hg2+ selective PVC membrane coated graphite electrode was developed based on schiff base network1. The best response was observed form the membrane composition of PVC (32 %), Nitrobenzene (60 %), sodium tetraphenylborate (2 %), and schiff base network1 (6 %). The designed sensor showed an excellent Nernstian response to Mercury (II) (29.8 mV. Decade−1) over a wide activity range from 1 × 10−7 to 5 × 10−3 and the detection limit of the proposed potentiometric sensor was 8 × 10−8. The effect of different interfering species on the potentiometric response of the suggested electrode was scrutinized by matched potential method (MPM) and no interference was observed. The performance of the developed electrode in partially non-aqueous mediums was also checked out and the obtained results showed the electrode can also be utilized in systems containing %20 organic solvents (ethanol and acetone). The response time and lifespan of the electrode were <10 S and 16 weeks respectively. In the end, the analytical performance of the fabricated sensor for the determination of Hg (II) in three different effluent samples was scrutinized and the obtained results were compared with a standard spectrophotometric technique.

Electrochemically Quantifying Oxygen Reduction Selectivity in Nonaqueous Electrolytes

Understanding the factors that govern the selectivity of the oxygen reduction reaction (ORR) has motivated the study of ORR in nonaqueous media, in which the proton donor can be controlled and molecular catalysts can be solubilized. Rotating ring-disc electrode (RRDE) voltammetry is a powerful method for quantifying ORR selectivity but requires that the ring electrode catalyze H2O2 oxidation at transport-limited rates. While the potentials and ring materials required to satisfy this requirement have been examined for aqueous electrolytes, they have not been systematically investigated for nonaqueous electrolytes despite the growing use of RRDE in these media. Herein, we report that conventional Pt ring electrodes and typical RRDE protocols for nonaqueous media do not give rise to mass-transport-limited H2O2 oxidation kinetics. Instead, H2O2 oxidation is strongly activation-controlled on Pt surfaces with kinetics that depend on the electrolyte and solvent. We identify Au as a superior catalyst for nonaqueous H2O2 oxidation and show that transport-limited H2O2 oxidation can be accessed on high-surface-area Au rings under certain electrolyte conditions. Additionally, we develop a protocol for calibrating and correcting for sluggish H2O2 oxidation kinetics. We show that these two methods provide improved estimates of H2O2 selectivity for ORR catalysis in certain nonaqueous electrolytes.

Design and development of a fluorometric and colorimetric sensor for toxic cyanide detection by pyridinium scaffolds: live cell imaging and real sample analysis

Pyridinium based indenophenanthiride (Me-INDP) has been synthesized via conventional method which en route detection of CN− ion in a non-aqueous medium. The sensing behavior of Me-INDP to detection of CN− ion in a biological system was investigated using U87 cell lines.

Ferrocene/ferrocenium, cobaltocene/cobaltocenium and nickelocene/nickelocenium: from gas phase ionization energy to one-electron reduction potential in solvated medium.

We propose a theoretical procedure for accurate determination of reduction potentials for three metallocene couples, Cp2M+/Cp2M, where M = Fe, Co and Ni. This procedure first computes the gas phase ionization energy (IE) using the explicitly correlated CCSD(T)-F12 method and includes the zero-point energy correction, core-valence electronic correlation, and relativistic and spin-orbit coupling effects. By means of Born-Haber thermochemical cycle, the one-electron reduction potential is obtained as the sum of the gas phase IE and the corresponding Gibbs free energies of solvation (ΔGsolv) for both the neutral and cationic species. Among the three solvent models (PCM, SMD and uESE) investigated here, it turns out that only the SMD model (computed at the DFT level) gives the best estimation of the value for "ΔGsolv(cation) - ΔGsolv(neutral)" and thus, combining with the accurate IE values, the theoretical protocol is capable of yielding reliable values (in V) for , and . These predictions compare favorably with the available experimental data (in V): , , and . We show that our theoretical procedure is reliable for accurate reduction potential predictions of Cp2Fe+/Cp2Fe, Cp2Co+/Cp2Co and Cp2Ni+/Cp2Ni redox couples in aqueous and non-aqueous media; the maximum absolute deviation is as small as ≈120 mV, which outperforms those of the existing theoretical methods.

The synergy between electrochemical substrate oxidation and the oxygen reduction reaction to enable aerobic oxidation.

Aerobic substrate oxidation reactions catalyzed by a heterogeneous catalyst can be looked upon as two independent half-cell reactions, viz. anodic substrate oxidation and the cathodic oxygen reduction reaction (ORR). In this context, Fe PANI/C, a well-known catalyst for the ORR, is chosen to validate this hypothesis, wherein the anodic reaction is hydrazine oxidation. Fe PANI/C shows excellent activity in terms of the electrochemical ORR and hydrazine oxidation in both alkaline aqueous and non-aqueous media and taken together the aerobic oxidation efficacy of hydrazine-like small organic molecules is correlated with the electrochemical outcomes.

The state-of-the-art in the electroreduction of NOx for the production of ammonia in aqueous and nonaqueous media at ambient conditions: a review

Mechanism studies in aqueous/nonaqueous solution are summarized. Electrode engineering on NOxRR-to-NH3 in aqueous solution is generalized. Electrolyte modifications strategies are analyzed towards operation conditions and electrolyte choosen.

Salt-Free and Alkali-Free Fixing Method of Wool Fabric Dyeing in Non-Aqueous Media Dyeing System

Salt-Free and Alkali-Free Fixing Method of Wool Fabric Dyeing in Non-Aqueous Media Dyeing System

Voltammetric investigations of functional dyspepsia drug acotiamide at pencil graphite electrode: An eco-friendly and cost effective stripping detection method

First time, the electro-oxidative behaviour and determination of acotiamide at a pencil graphite electrode have been investigated under different experimental conditions using cyclic voltammetry (CV), differential pulse anodic stripping voltammetry (DPASV), and square wave anodic stripping voltammetric (SWASV) techniques. The voltammetric responses of acotiamide have been analyzed at different scan rates, pH and concentrations. Oxidation of acotiamide at the surface of pencil graphite electrode gave two well defined irreversible peaks in the voltammograms in BR buffer of pH 7.0. The oxidation process is completely diffusion controlled. A linear response of peak current has been obtained between 15.5 to 124 μM in non-aqueous media for all the voltammetric techniques. The proposed DPASV and SWASV techniques show limit of detection at 18.58 and 13.36 μM, respectively.

Using an eco-friendly deep eutectic solvent for waterless anti-felting of wool fibers

Anti-felting or felting resistance process is a major finishing process for woolen goods which guarantees the dimensional stability of the product in washing and cleaning procedures mainly by covering or removing the scales from the surface of the wool fibers. Today, about 90 percent of anti-felting operations are carried out in a water-based chlorination process which releases tons of chlorine-containing discharge into the environment. Here we introduced deep eutectic solvents (DESs) as green substitutes for non-environmentally friendly sodium hypochlorite for getting anti-felting properties on woolen goods. Response surface methodology (RSM) based on four factors and in three levels, using Box-Behnken design (BBD) was used for designing the experiments and optimizing effective parameters in the anti-felting process of wool fibers using DESs. It was found that a special DES called Reline which is a mixture of choline chloride and urea in a 1:2 M ratio can successfully work as a green anti-felting agent and non-aqueous reaction medium. The shrinkage percentage of the Reline (DES) treated wool was 10% and very close to the 8.56% shrinkage seen on the hypochlorite-treated wool sample compared to more than 32% shrinkage observed on untreated fibers. Reline exhibited better preservation of the physicochemical and mechanical properties of the fibers causing only a 6.04% reduction in the breaking load of wool fibers compared to the hypochlorite-treated sample with a 24.86% reduction in breaking load of fibers. Anti-felted wool using the new Reline agent exhibit much better whiteness and lower yellowness compared to the chlorine-treated fibers. Microscopical observations, reflectance spectrophotometry, and tensile measurements all confirmed the superiority and numerous advantages of using Reline as a green anti-felting agent instead of polluting chlorinated chemicals. Reline usage as a green chemical encompasses other benefits such as reduced water consumption, reduced effluent, and more importantly DES recyclability and reuse.

Preparation of catalyst from natural montmorillonite mineral and its application in the synthesis of carbon nanosphere

In developed countries, nanoparticles derived from natural minerals and high-purity chemicals both are widely studied, while in developing countries like Mongolia, the natural minerals-based nanoparticles have more interest because of the low production cost and applicability of domestic natural minerals for their production. For the synthesis of natural mineral-based nanomaterials, it is important first to define the chemical composition and physical structure of local minerals and their possible processing route. We employed an environmentally friendly alkaline leaching procedure to recover silica from the clay mineral at 90°C for 24 hours. We applied an organic surfactant (CTAB) and a simple coprecipitation approach to form iron-doped silica nanoparticles. Consequently, we used iron-doped silica nanoparticles as a substrate and catalyst for the synthesis of carbon nanosphere at 750 °C for 1 hour in an argon and acetylene gas atmosphere. As a result, vast quantities of superhydrophobic carbon nanospheres (CNS) were obtained. The physicochemical properties of nanosilica substrate, non-functionalized carbon nanosphere, and functionalized carbon nanosphere (CNS) samples were characterized using XRD, XRF, SEM, EDS, TEM, and FTIR spectrometer. Iron-doped mineral-derived nanosilica particles demonstrated high catalytic efficiency and the potential to produce a large amount of value-added carbon nanospheres. Superhydrophobic CNS can be used in a variety of applications, particularly drug delivery; however, to use CNS in both aqueous and non-aqueous media, the superhydrophobic properties of CNS can be modified using different oxidizers. The changes in hydrophobicity of the CNS were examined and suggested possible oxidizing agents.

Investigating the solvation behavior of some perchlorates in non-aqueous medium and predicting their ion-solvation thermodynamics using Born formula

A systematic study of volumetric, acoustic properties and thermodynamics of ion solvation, from appropriate data of sound velocity, density and conductivity of RNH3ClO4 (R is Ethyl, n-Propyl, n-Hexyl and n-Octyl) in binary mixtures of acetonitrile (AN) and dimethyl sulfoxide (DMSO) has been made at different temperatures. Various acoustical parameters like relaxation strength (r), Rao’s constant (R), Wada’s constant (W), available volume (Va), van der Waals constant (b) and apparent molal volume (Vɸ) were assessed through the experimental data of density and sound velocity at T = (298, 308, 318 and 328) K and at P = 0.1 MPa pressure. From the data of apparent molal volume, other parameters like limiting apparent molal expansibilities ϕEο and Hepler’s constant (∂ϕEο/∂T)p that helps in determining the structure making and structure breaking ability of solute in the solutions, were evaluated. In the second part of this work, the solvated radii (ri) of alkylammonium (RNH3+) and perchlorate (ClO4-) ions have been determined in the binary mixtures of AN-DMSO solvent system at four investigated temperatures. The solvated radii data is then fitted to modified Born equations, whose provenance and implications are discussed and is utilized to evaluate thermodynamics of solvation in terms of free energy change (ΔGI-S), entropy change (ΔSI-S) and enthalpy change (ΔHI-S) of ion–solvent interactions. It is shown that, the plot of ΔGI-S as a function of 1/ri is linear, indicating the investigated system to follow Born equations. Overall, the results obtained from volumetric, acoustic and thermodynamic data, indicates the possibility of effective solute–solvent interactions amidst the investigated system.

Coupling Nonstoichiometric Zn0.76Co0.24S with NiCo2S4 Composite Nanoflowers for Efficient Synergistic Electrocatalytic Oxygen and Hydrogen Evolution Reactions

Transition-metal sulfide-based composite nanomaterials have garnered extensive interest not only for their unique morphological architectures but also for exploring as a noble-metal-free cost-effective, durable, and highly stable catalyst for electrochemical water splitting. In this work, we synthesized in situ nonstoichiometric Zn0.76Co0.24S with NiCo2S4 binary composite flowers (Zn0.76Co0.24S/NiCo2S4) in one step by thermal decomposition of Zn2[PDTC]4 and Ni[PDTC]2 complexes by a solvothermal process in a nonaqueous medium from their molecular precursor, and their potential application in electrochemical oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) was investigated. Field-emission scanning electron microscopy and transmission electron microscopy analyses revealed the flower-shaped morphology of as-synthesized Zn0.76Co0.24S/NiCo2S4. Again, the structural and chemical compositions were confirmed through powder X-ray diffraction and X-ray photoelectron spectroscopy studies, respectively. The as-obtained 3D flower-type Zn0.76Co0.24S/NiCo2S4 nanostructure was further subject to electrochemical OER and HER in alkaline and acidic media, respectively. Zn0.76Co0.24S/NiCo2S4 showed low overpotential values of 248 mV (Tafel slope, 85 mV dec–1) and 141 mV (Tafel slope, 79 mV dec–1) for OER and HER activities, respectively, due to the synergistic effects of Zn0.76Co0.24S and NiCo2S4. Several long-term stability tests also affirmed that the Zn0.76Co0.24S/NiCo2S4 composite nanostructure is a highly stable and efficient electrocatalyst toward OER and HER activities as compared to the recently reported superior bifunctional electrocatalysts as well as state-of-the-art materials.

New electroanalytical method for the determination of trans-anethole in spices and sweets

A completely new method for the determination of trans–anethole (TAN) based on the anodic oxidation of this flavouring substance in pure acetonitrile using differential–pulse voltammetry has been developed. A nonaqueous carbon paste electrode bulk-modified with solid sodium dodecyl sulphate of 40 % (w/w) content was chosen as optimum. To propose TAN electrode reaction mechanism, its electrochemical behaviour was investigated at glassy carbon electrode in nonaqueous media. At optimum working conditions, the current response could be calibrated within a linear range 2–200 µmolL−1 TAN, a coefficient of determination of 0.9971, a sensitivity of 0.1122µALµmol−1, and a detection limit of 0.7 µmolL−1. A satisfactory precision (relative standard deviation of 4 %) has been achieved. The validation performed by analysis of spices and sweets provided comparable results with reference reverse–phase HPLC with spectrophotometric detection, thus confirming the practical use of the developed voltammetric method in food analysis.

Structurally and electrochemically tunable pyrylium platforms: A new class of redox anolyte for non-aqueous organic redox flow battery operating at a high-current density

Non-aqueous all-organic redox flow batteries (NORFB) are a proficient candidate for large-scale energy storage applications. The higher operating potential window of non-aqueous solvents, diversity of redox-active organic molecules (ROMs), and independent scaling of power and energy, etc., captivate NORFB to be a potential choice for grid energy storage applications. Besides, the invention of new redox-active motifs significantly expands the development of NORFBs; thus, it is highly demanded. But, the low operational current density and slower redox kinetics are the bottlenecks for the further development of NORFB. Herein, we introduced a new class of anolyte material based on pyrylium salt (2,4,6-triphenylpyrylium tetrafluoroborate (TPT)) and demonstrated for the first time its applicability as a potential anolyte in NORFB. The substitutions at the 2, 4, and 6th positions of pyrylium salt prominently tune the structural and electrochemical behavior, thus providing a versatile platform to explore them in flow battery chemistry. TPT exhibited a one-electron reduction process with a high electron transfer rate constant of 9.94 × 10−3 cm s−1 and diffusion coefficient of 5.83 × 10−6 cm2 s−1, which is higher for the non-aqueous medium. By coupling with N-decylphenothiazine (DPTZ) catholyte, a mixed electrolyte flow cell was demonstrated with a capacity of 1.08 Ah/L and coulombic efficiency of 97 % at a high current density of 40 mA cm−2.

Electrochemical and in-situ spectroelectrochemical properties of novel (5-(tert-butyl)-2-((3,4-dicyanophenoxy)methyl)phenyl)methanolate substituted mononuclear metal phthalocyanines

This work involves the synthesis and characterization of metallic (Co, Fe, Mn, Ni, Zn) ball-type phthalocyanine precursors by using novel 4,4′-(((4-(tert-butyl)-1,2-phenylene)bis-(methylene))bis(oxy))diphthalonitrile starting compound. The classical oxo-bridge in phthalocyanines was altered with the -OCH2- bridge first time for these ball-type phthalocyanine precursors, and the effects of this change on the chemical, physical and spectral features of phthalocyanine complexes were investigated, in the study. The redox properties of phthalocyanines were researched by electrochemical and in situ spectroelectrochemical measurements on a Pt working electrode in non-aqueous medium. The color changes involved in the redox processes were observed via in situ electrocolorimetric techniques. Electrochemical and UV–Vis spectral measurements exhibited that the compounds had reversible and serial one-electron reduction and oxidation processes. Furthermore, they also had nitrile reduction processes because of opened nitrile groups located at peripheral tails of the phthalocyanine complexes. The plentiful redox conducts of the complexes such as Pc ring based and/or central redox active metal-based reduction and oxidation reactions at low potentials showed that these complexes can be used as functional materials. Because of the apparent spectral and net color changes, the complexes are suitable for utilization in electrochromic devices. Moreover, their rich redox features are a sign of their high electrocatalytic activity for oxygen reduction.