Anhydrous System Research Articles

Electrochemical mechanism and kinetics of electrodissolution-coupled hafnium alkoxide synthesis in tetraethylammonium-chloride-based anhydrous system

Electrodissolution-coupled hafnium alkoxide synthesis (EHS) is a promising pathway for efficient electro- synthesis. It employs simultaneous heterogeneous reactions of Hf dissolution and ethanol dehydrogenation, and spontaneous solution-based combination reaction between Hf4+ cations and alkoxy anions. To elucidate the mechanism and kinetics of EHS process, the electrochemical behaviors of anodic Hf dissolution and cathodic ethanol dehydrogenation were explored through electrochemical measurements, SEM observations, gas chromatography, and micro-kinetics modeling. The results indicated the supporting electrolytes of tetraethylammonium chloride (Et4NCl) to be preferable, which facilitated a passive-film-punctured pitting mechanism for Hf dissolution and a two-stage dehydrogenation mechanism. Three indicators related to passive rate, sensitivity towards puncture of the passive film, and pitting rate were extracted to quantify the kinetics of passive puncture and Hf corrosion. Micro-kinetics models were developed to evaluate the Et4NCl-based EHS process, which achieved electric energy requirements of 1.53–1.83 kW·h/kg Hf(OC2H5)4.

Three-Dimensional Printed Shape Memory Gels Based on a Structured Disperse System with Hydrophobic Cellulose Nanofibers.

Inks for 3D printing were prepared by dispersing bacterial cellulose nanofibers (CNF) functionalized with methacrylate groups in a polymerizable deep eutectic solvent (DES) based on choline chloride and acrylic acid with water as a cosolvent. After 3D printing and UV-curing, the double-network composite gel consisting of chemically and physically crosslinked structures composed from sub-networks of modified CNF and polymerized DES, respectively, was formed. The rheological properties of inks, as well as mechanical and shape memory properties of the 3D-printed gels, were investigated in dynamic and static modes. It was shown that the optimal amount of water allows improvement of the mechanical properties of the composite gel due to the formation of closer contacts between the modified CNF. The addition of 12 wt% water results in an increase in strength and ultimate elongation to 11.9 MPa and 300%, respectively, in comparison with 5.5 MPa and 100% for an anhydrous system. At the same time, the best shape memory properties were found for an anhydrous system: shape fixation and recovery coefficients were 80.0 and 95.8%, respectively.

Effect of alcohols on CO2 absorption, phase splitting, and desorption behaviors of biphasic anhydrous system: The primary amine-tertiary amine of DGA-PMDETA

Chemical absorption with organic amine solution is the most mature technology for CO2 capture. Some biphasic anhydrous absorbents show potential in reducing regeneration energy consumption, but high viscosity of the CO2 rich phase hinders its practical application. Alcohols are commonly employed as dilutes to reduce viscosity reducers, while its effect on CO2 absorption and phase splitting behaviors are still unclear. In this study, the effects of alcohols on CO2 absorption and phase-splitting of biphasic anhydrous 2-(2-Aminoethoxy)ethanol (DGA) -N,N,N′,N″,N″-pentamethyl diethylenetriamine (PMDETA) -alcohol systems are investigates. Adding alcohol reduces the viscosity of the CO2-rich phase, enhances desorption rate, and decreases the phase splitting time. The rich phase entrainment stage and the rich phase thickening stage, can be distinguished along with during CO2 absorption. The majority DGA reacts with CO2 in the rich phase since the phase splitting begins. This work may provide some basis for further biphasic absorbent design and regulation.

Gallic acid-modified bioglass with combined photothermal and antibacterial effects for the regeneration of infected diabetic wound

Diabetes-associated chronic wound management has been a serious worldwide issue, which is obstructed by multiple factors such as sustained inflammation, attenuated angiogenesis, and fragile defense against bacterial infection in the wound niche. Thus, there stands an urgent demand for biomaterial dressings that are able to treat such complex conditions. Herein, we developed a composite biomaterial of gallic acid-modified bioglass (GA@BG) in an anhydrous system, by using two agents which have already been used in clinical practice. The prepared GA@BG not merely promoted the migration and angiogenesis of vascular endothelial cells but also provided superior antibacterial performance in the local environment. Significantly, the gallic acid-assisted modification made the color of bioglass (BG) change from white to black, endowing it with high light absorption to successfully achieve a significant photothermal property. Then, the strengthened antibacterial effects were further realized by irradiation with near-infrared light (NIR) based on this photothermal property. Particularly, the combined therapy (GA@BG + NIR) was demonstrated as an effective strategy in treating the infected full-thickness dermal wounds of diabetic rats. This research provides a convenient non-antibiotic medicine formula for diabetic wounds with infection, and demonstrates a valid modification for inorganic bioglass-based material with organic polyphenol, which inspires more expansive composites for wound biomaterials.

Thermal investigation on hydrated co-amorphous systems of nicotinamide and prilocaine

It is generally recognized that water, acting as a plasticizer, increases molecular mobility, leading to a decrease of the glass transition temperature (Tg) in amorphous systems. However, an anti-plasticizing effect of water was recently observed on prilocaine (PRL). This effect might be used in co-amorphous systems to moderate the plasticizing effect of water. Nicotinamide (NIC) can form co-amorphous systems with PRL. In order to investigate the effect of water on these co-amorphous systems, the Tgs and molecular mobility of hydrated co-amorphous NIC-PRL systems were compared with those of the respective anhydrous systems. Molecular mobility was estimated by considering the enthalpic recovery at the Tg using the Kohlrausch-Williams-Watts (KWW) equation. At molar ratios of NIC above 0.2, a plasticizing effect of water on co-amorphous NIC-PRL systems was observed with increasing the NIC concentration. In contrast, at molar ratios of NIC of 0.2 and below, water had an anti-plasticizing effect on the co-amorphous NIC-PRL systems, with increased Tgs and reduced mobility upon hydration.

Anodic Behavior of Hafnium in Anhydrous Electrodissolution-Coupled Hafnium Alkoxide Synthesis

The electrodissolution-coupled hafnium alkoxide (Hf(OR)4, R is alkyl) synthesis (EHS) system, which has significant environmental and economic advantages over conventional thermal methods, serves as a promising system for green and efficient Hf(OR)4 electro-synthesis. The EHS system is operated based on the simultaneous heterogeneous reactions of hafnium dissolution and ethanol dehydrogenation, as well as the spontaneous solution-based reaction of Hf4+ and OR−. Employing green ethanol and Hf as feedstocks, the anodic hafnium corrosion/dissolution electrochemical behavior of the Et4NCl or Et4NHSO4 based anhydrous system was investigated through electrochemical measurements combined with SEM observations. The results demonstrated that the Et4NCl-based anhydrous ethanol system exhibited an efficient mechanism of passive film pitting corrosion breakdown and metal hafnium dissolution, while the Et4NHSO4-based anhydrous ethanol system reflected the weak corrosion mechanism of the anodic hafnium under the passive film. The polarization resistance of the Et4NCl system was dramatically lower than that of the Et4NHSO4 system, which indicated that the Et4NCl system had superior anodic hafnium corrosion performance compared to the Et4NHSO4 system. Overall, the investigation of the electrochemical behaviors of anodic hafnium corrosion/dissolution provides theoretical guidance for the efficient operation of EHS electrolysis.

Tailoring proton transfer species on the membrane surface: An approach to enhance proton conductivity for polymer electrolyte membrane fuel cell

The efficiency of proton conductivity in proton exchange membrane (PEM) depends on how proton species can effectively transfer through the membrane either in hydrous system or anhydrous system. Although the incorporation of proton donors and/or acceptors via chemical modification, blending, including preparing composites in polymer solution state before casting the membrane is a general approach, the proton transfer species may not be effectively functioned as they were randomly existed in PEM. As proton transfer initially occurs at the PEM surface, the decoration of the proton transfer species on the surface can be considered as an alternative choice to develop PEM. The surface modifications can be carried out by attaching the functional molecules and/or polymers to favor the proton transfer. The present review summarizes the approaches to construct the PEM surface with proton conductive species, especially via layer-by-layer, and polymer brushes to enhance the PEM performances.

Porous defective carbon ferrite for adsorption and photocatalysis toward nitrogen compounds in pre-treated biogas slurry

Carbon ferrite (C-Fe3O4) with hydrophilic functional groups and lattice defects was synthesized in anhydrous molten alkali system by fern leaves and ferric chloride as raw materials. Structural characterization results showed that carbon ferrite obtained oxygen-containing groups on the carbon surface. And structural pores and lattice defects resulted from spontaneous accumulation and “directive-connection” of ferrite (Fe3O4) nanoparticles. Carbon ferrite displayed an adsorption efficiency of 29.0% and excellent photocatalytic degradation of 80.8% toward nitrogen compounds (initial concentration of 430 mg/L) in pre-treated biogas slurry. The micromechanism for nitrogen compounds removal was discussed at the molecular/atomic level by exploring carbon ferrite “structure-activity”, which provides a design idea from microscopic perspective for the preparation of environmental materials with reactive sites.

Source characterisation of the residual lherzolite and harzburgite ultramafics of Manipur Ophiolite Belt in the Indo–Myanmar Hill ranges, NE India

An attempt for the calculation of primordial mineralogy of the source rock of the ultramafics of Manipur ophiolite, north‐east India is made with the use of an established schematic ternary phase diagram of the anhydrous system Forsterite‐Diopside‐Enstatite at 20 kb pressure for a hypothetical upper mantle rock (X). For the case of batch partial melting, if the proportions of the phases entering the melt (Pα) are different from their initial proportion in the rock (X0α), then the weight fraction of the melt (F) at which each phase in question is consumed is given by F = X0α/Pα. From the phase diagram, the bulk composition of the source rock X can be expressed as 0.4 Di, 0.2 En, and 0.4 Fo (these are the X0α values). The proportion (Pα) in which the various phases entered the melt is initially given by the proportion in the eutectic composition E, that is, 0.7 Di, 0.2 En, 0.1 Fo. With the value of Fcpx = 0.4/0.7 = 0.57, it is found that the diopside is the only phase to be completely consumed into the partial melt, which occurs at 57% partial melting. The least serpentinized group of ultramafics of the Ophiolite Belt in Manipur is considered to be the residue of those which have suffered the least percent of partial melting (about 5%), and the average proportions of the three main phases of such rocks are taken as yardsticks for necessary calculation of the primordial mineralogy of the upper source rock. From the computed value of Fcpx (Mo) = 0.14, it is inferred that the diopside in the original source rock of Manipur Ophiolite must be completely melted at about 15% partial melting as against 57% of the hypothetical mantle rock discussed in the phase diagram. Thus, at about 15% partial melting of the source rock of Manipur Ophiolite, the levels of melting of the three main phases, as derived from the phase diagram, is calculated to be, Diopside = 100%, Enstatite = 57%, and Olivine = 14%. From these values of levels of melting, the different degrees of melting of the three main phases have been computed separately for 5%, 10%, 15%, and 20% bulk partial melting. From the modal proportions of the main phases of the least serpentinized ultramafics of Manipur Ophiolite (considered to be a residue of 5% partial melting), the mineralogical proportions of the original source rock are computed and these are found to correspond to Spinel Lherzolite composition.

Synthesis of Novel Quinazolin-4-one hybrids as potential antimicrobial agents

We have developed an effortless and extremely efficient procedure for the synthesis of quinazolin-4-one derivatives via palladium-catalyzed C-Ccoupling of aryl amide with isocyanides. The reactions are operationally simple and avoid using toxic carbon monoxide and acid chloride, which must be used in an anhydrous system. The structure of the novel compounds was confirmed based on spectral data. We also demonstrated the biological potential of these compounds as novel Antifungal Activity. Based on the MIC results, the most active is 3g.

Electrochemical Mechanism and Kinetics of Electrodissolution- Coupled Hafnium Alkoxide Synthesis in a Tetraethylammonium-Chloride-Based Anhydrous System

Electrochemical Mechanism and Kinetics of Electrodissolution- Coupled Hafnium Alkoxide Synthesis in a Tetraethylammonium-Chloride-Based Anhydrous System

Evolution of nC16H34-water–mineral systems in thermal capsules and geological implications for deeply-buried hydrocarbon reservoirs

Organic-inorganic interactions between hydrocarbons and most minerals in deeply buried reservoirs remain unclear. In this study, gold capsules and fused silica capillary capsules (FSCCs) with different combinations of nC16H34, water (distilled water, CaCl2 water) and minerals (quartz, feldspar, calcite, kaolinite, smectite, and illite) were heated at 340 °C for 3–10 d, to investigate the evolution and reaction pathways of the organic–inorganic interactions in different hot systems.After heating, minerals exhibited little alteration in the anhydrous systems. Mineral alterations, however, occurred obviously in the hydrous systems. Different inorganic components affected nC16H34 degradation differently. Overall, water promoted the free-radical thermal-cracking reaction and step oxidation reaction but suppressed the free-radical cross-linking reaction. The impact of CaCl2 water on the nC16H34 degradation was weaker than the distilled water as high Ca2+ concentration suppressed the formation of free radicals. The presence of different waters also affects the impact of different minerals on nC16H34 degradation, via its impact on mineral alterations. In the anhydrous nC16H34-mineral systems, calcite and clays catalyzed generation of low-molecular-weight (LMW) alkanes, particularly the clays. Quartz, feldspar, and calcite catalyzed generation of high-molecular-weight (HMW) alkanes and PAHs, whereas clays catalyzed the generation of LMW alkanes and mono-bicyclic aromatic hydrocarbons (M-BAHs). In the hydrous nC16H34-distilled water–mineral systems, all minerals but quartz promoted nC16H34 degradation to generate more LMW alkanes, less HMW alkanes and PAHs. In the nC16H34-CaCl2 water–mineral systems, the promotion impact of minerals was weaker than that in the systems with distilled water.This study demonstrated the generation of different hydrocarbons with different fluorescence colors in the different nC16H34-water–mineral systems after heating for the same time, implying that fluorescence colors need to be interpreted carefully in investigation of hydrocarbon charging histories and oil origins in deeply buried reservoirs. Besides, the organic–inorganic interactions in different nC16H34-water–mineral systems proceeded in different pathways at different rates, which likely led to preservation of liquid hydrocarbons at different depth (temperature). Thus, quantitative investigations of the reaction kinetics in different hydrocarbon-water-rock systems are required to improve the prediction of hydrocarbon evolution in deeply buried hydrocarbon reservoirs.

Strategies for the Immobilization of Eversa® Transform 2.0 Lipase and Application for Phospholipid Synthesis

Eversa® Transform 2.0 lipase (ET2) is a recent lipase formulation derived from the Thermomyces lanuginosus lipase cultivated on Aspergillus oryzae and specially designed for biodiesel production. Since it has not been available for a long time, research on the efficiency of this enzyme in other applications remains unexplored. Moreover, even though it has been launched as a free enzyme, its immobilization may extend the scope of ET2 applications. This work explored ET2 immobilization on octadecyl methacrylate beads (IB-ADS-3) and proved the efficiency of the derivatives for esterification of glycerophosphocholine (GPC) with oleic acid in anhydrous systems. ET2 immobilized via interfacial activation on commercial hydrophobic support Immobead IB-ADS-3 showed maximum enzyme loading of 160 mg/g (enzyme/support) and great stability for GPC esterification under 30% butanone and solvent-free systems. For reusability, yields above 63% were achieved after six reaction cycles for GPC esterification. Considering the very high enzyme loading and the number of reuses achieved, these results suggest a potential application of this immobilized biocatalyst for esterification reactions in anhydrous media. This study is expected to encourage the exploration of other approaches for this enzyme, thereby opening up several new possibilities.

A “special” anhydrous system for the preparation of alloyed Pd1Ce0.5 nanonetworks catalyst supported on carbon nanotubes with high electrochemical oxidation activity for formic acid

Herein, Pd1Ce0.5 alloy nanonetworks (ANNs) on multi-walled carbon nanotubes (MWCNTs) supported bimetallic catalyst (referred to Pd1Ce0.5/MWCNTs-D) was prepared in deep eutectic solvents (DESs). The Pd1Ce0.5/MWCNTs-D catalyst shows remarkable catalytic performance toward formic acid oxidation (FAO) (1968.5 mA mgPd−1) and better CO anti-poisoning capability compare with Pd/MWCNTs-D, Pd/MWCNTs-W (prepared in water) and commercial Pd/C catalysts. The excellent network structure and synergistic effect are the main reasons for the improvement of electrochemical activity of Pd1Ce0.5/MWCNTs-D catalyst. This study provides a new method for preparation of high performance Pd-based electrocatalysts for direct formic acid fuel cell (DFAFC) applications.

Mechanistic insight into B(C6F5)3 catalyzed imine reduction with PhSiH3 under stoichiometric water conditions.

A DFT and experimental study on the mechanism of B(C6F5)3 catalyzed imine reduction is performed using PhSiH3 as reductant under stoichiometric water conditions. Ingleson’s path B is reconfirmed here. And four novel (C6F5)3B–OH2 induced pathways (paths C2, C3, D2 and D3) entirely different from all the previous mechanisms were determined for the first time. They are all B(C6F5)3 and water/amine catalyzed cycles, in which the nucleophilic water or amine catalyzed addition step between PhSiH3 and the N-silicon amine cation is the rate-determining step of paths C2/D2 and C3/D3 with activation Gibbs free energy barriers of 23.9 and 18.3 kcal mol−1 in chloroform, respectively, while the final desilylation of the N-silicon amine cation depends on an important intermediate, (C6F5)3B–OH−. The competitive behavior of the 5 paths can explain the experimental facts perfectly; if all the reactants and catalysts are added into the system simultaneously, water amount and nucleophiles (excess water and produced/added amine) provide on–off selectivity of the pathways and products. 1 eq. water leads to quick formation of (C6F5)3B–OH−, leading to B-II being turned off, and nucleophiles like excess water and produced/added amine switch on CD-II, leading to production of the amine. B-I′ of Ingleson’s path B is the only mechanism for anhydrous systems, giving N-silicon amine production only; B-I and C-I are competitive paths for systems with no more than 1 eq. water, producing the N-silicon amine and the [PhHC Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> NHPh]+[(C6F5)3B–OH]− ion pair; and paths C2, C3, D2 and D3 are competitive for systems with 1 eq. water and nucleophiles like excess water or added/produced amine, directly giving amination products.

Structural, electronic, and magnetic properties of nearly ideal Jeff=12 iridium halides

Heavy transition metal magnets with $J_{\rm eff}$ $=$ 1/2 electronic ground states have attracted recent interest due to their penchant for hosting new classes of quantum spin liquids and superconductors. Unfortunately, model systems with ideal $J_{\rm eff}$ $=$ 1/2 states are scarce due to the importance of non-cubic local distortions in most candidate materials. In this work, we identify a family of iridium halide systems [i.e. K$_2$IrCl$_6$, K$_2$IrBr$_6$, (NH$_4$)$_2$IrCl$_6$, and Na$_2$IrCl$_6 \cdotp $ 6(H$_2$O)] with Ir$^{4+}$ electronic ground states in extremely close proximity to the ideal $J_{\rm eff}$ $=$ 1/2 limit, despite a variation in the low-temperature global crystal structures. We also find ordered magnetic ground states for the three anhydrous systems, with single crystal neutron diffraction on K$_2$IrBr$_6$ revealing Type-I antiferromagnetism. This spin configuration is consistent with expectations for significant Kitaev exchange in a face-centered-cubic magnet.

Ag/black phosphorus composite based on multilayer black phosphorus: Its preparation and photocatalytic methyl orange degradation performance

In this study, a new method is proposed for the preparation of Ag/black phosphorus composite in an anhydrous system. Before the preparation, black phosphorus (BP) bulk is firstly preprocessed by a wet ball milling method combined with sodium hydroxide, so that BP can be functionalized and a large proportion (80%) of micro-multilayer BP flakes (MBP) with hydroxyl groups can be used. Then the addition of ethylene glycol and polyvinylpyrrolidone into the synthesis system prevents agglomeration of hydroxylated MBP flakes and enables the uniform distribution of Ag+ on BP flakes, thereby yielding an Ag/MBP composite with Ag nanoparticles uniformly dispersed on BP flakes. XRD, Raman, and XPS results indicate that the BP with its lattice structure is retained in Ag/MBP. In fact, neither Ag nor hydroxylated MBP shows photocatalytic activity; however, in the presence of Ag/MBP, methyl orange (MO) is completely degraded within 85 min under irradiation with light of wavelength 300–2500 nm. The well dispersed Ag nanoparticles enhance the absorption of high-intensity light and facilitate the transfer of photogenerated e− from BP, finally facilitating the separation of h+ and e−. Superoxide radical (·O2−) and holes (h+) are identified to be the active radicals directly involved in the degradation of MO.

Formation of Samin Diastereomers by Acid-Catalyzed Transformation of Sesamolin with Hydrogen Peroxide.

The conversion of sesame lignans is of interest because the derived products may have potential applications. Here, in investigating the transformation of sesamin and sesamolin, main endogenous sesame lignans in sesame seeds, in both acidic aqueous and anhydrous systems, 7R,7'S-samin was identified as one of the major products of sesamolin in both systems catalyzed with common inorganic acids, but sesaminol was not generated. In investigating the effect of different oxidizing agents on the acid-catalyzed conversion of sesame lignans, 7R,7'S-samin was still the major product of sesamolin, whereas sesamolin as well as 7R,7'S-samin stereoselectively rendered 7R,7'R-samin in the presence of hydrogen peroxide. Hydrogen peroxide may play a role in stabilizing the transitional oxonium ions, derived from acid hydrolysis of sesamolin or 7R,7'S-samin by forming a seven-membered ring intermediate through hydrogen bonding, to consequently produce 7R,7'R-samin as the final product.

Large H2O solubility in dense silica and its implications for the interiors of water-rich planets

Sub-Neptunes are common among the discovered exoplanets. However, lack of knowledge on the state of matter in [Formula: see text]O-rich setting at high pressures and temperatures ([Formula: see text]) places important limitations on our understanding of this planet type. We have conducted experiments for reactions between [Formula: see text] and [Formula: see text]O as archetypal materials for rock and ice, respectively, at high [Formula: see text] We found anomalously expanded volumes of dense silica (up to 4%) recovered from hydrothermal synthesis above ∼24 GPa where the [Formula: see text]-type (Ct) structure appears at lower pressures than in the anhydrous system. Infrared spectroscopy identified strong OH modes from the dense silica samples. Both previous experiments and our density functional theory calculations support up to 0.48 hydrogen atoms per formula unit of ([Formula: see text])[Formula: see text] At pressures above 60 GPa, [Formula: see text]O further changes the structural behavior of silica, stabilizing a niccolite-type structure, which is unquenchable. From unit-cell volume and phase equilibrium considerations, we infer that the niccolite-type phase may contain H with an amount at least comparable with or higher than that of the Ct phase. Our results suggest that the phases containing both hydrogen and lithophile elements could be the dominant materials in the interiors of water-rich planets. Even for fully layered cases, the large mutual solubility could make the boundary between rock and ice layers fuzzy. Therefore, the physical properties of the new phases that we report here would be important for understanding dynamics, geochemical cycle, and dynamo generation in water-rich planets.

Does the trihydrate of atorvastatin calcium possess a melting point?

To decide whether an active pharmaceutical ingredient can be used in its amorphous form in drug formulations, often the glass transition is studied in relation to the melting point of the pharmaceutical. If the glass transition temperature is high enough and found relatively close to the melting point, the pharmaceutical is considered to be a good glass former. However, it is obviously important that the observed melting point and glass transition involve exactly the same system, otherwise the two temperatures cannot be compared. Although this may seem trivial, in the case of hydrates, where water may leave the system on heating, the composition of the system may not be evident. Atorvastatin calcium is a case in point, where confusing terminology, absence of a proper anhydrate form, and loss of water on heating lead to several doubtful conclusions in the literature. However, considering that no anhydrate crystal has ever been observed and that the glass transition of the anhydrous system is found at 144 °C, it can be concluded that if the system is kept isolated from water, the chances that atorvastatin calcium crystallises at room temperature is negligible. The paper discusses the various thermal effects of atorvastatin calcium on heating and proposes a tentative binary phase diagram with water.