Initial Molar Ratio Research Articles

Ternary-like Aqueous Biphasic Systems Composed of Betaine-Polyol Deep Eutectic Solvents and n-Propanol

A deep eutectic solvent (DES)-based aqueous biphasic system (ABS) denotes a clean and highly biocompatible separation and purification technology, but the explanations of the phase formation mechanism and phase behavior of a DES-based ABS are incomplete. To improve the study of the formation mechanism of a DES-based ABS, a new ABS composed of n-propanol (NPA) and DES with betaine as the hydrogen-bond acceptor (HBA) and polyol as the hydrogen-bond donor (HBD) was formed. The phase formation mechanism of this new ABS and the stability of the DES in the ABS were studied. Betaine and three polyols are hydrophilic (log KOW < 0), whereas NPA is relatively hydrophobic (log KOW > 0). Two phases were formed, because the two components of DES were incompatible with the NPA. The molar ratio of the HBA and HBD in the two phases differed, but in the bottom phase of this ABS, the stoichiometric ratio of HBA and HBD was the same as their initial ratio. Under certain conditions, this novel ABS was considered a ternary-like system. The combination of a series of factors, such as HBD hydrophilicity, molar volume, molecular weight, and initial molar ratio of HBA and HBD, affected the final stoichiometric ratio of HBA and HBD in the top phase.

Oxygenic Enrichment in Hybrid Ruthenium Sulfide Nanoclusters for an Optimized Photothermal Effect.

Transition-metal dichalcogenide (TMD)-based nanomaterials have been extensively explored for the photonic therapy. To the best of our knowledge, near-infrared (NIR) light is a requirement for the photothermal therapy (PTT) to achieve the feature of deep-tissue penetration, whereas no obvious absorption peaks existing in the NIR region for existing TMD nanomaterials limit their therapeutic efficacy. As one category of TMD nanomaterials, ruthenium sulfide-based nanomaterials have been less exploited in biomedical applications including tumor therapy so far. Here, we develop a facile biomineralization-assisted bottom-up strategy to synthesize oxygenic hybrid ruthenium sulfide nanoclusters (RuSx NCs) by regulating the oxygen amounts and sulfur defects for the optimized PTT. By regulating the increasing initial molar ratios of Ru to S, RuSx NCs with small sizes were endowed with increasing oxygen contents and sulfur defects, leading to the photothermal conversion efficiency (PCE) increasing from 32.8 to 41.9%, which were higher than that of most small-sized inorganic photothermal nanoagents. In contrast to commercial indocyanine green, these RuSx NCs exhibited higher photostability under NIR laser irradiation. The high PCE and superior photostability allowed RuSx NCs to effectively and completely ablate cancer cells. Thus, the proposed defect engineering strategy endows RuSx NCs with an excellent photothermal effect for the PTT of tumors of living mice, which also proves the potential of further exploring the properties of RuSx NCs for future biomedical applications.

Oxidative Degradation of Hazardous Benzene Derivatives by Ferrate(VI): Effect of Initial pH, Molar Ratio and Temperature.

Two of the most hazardous benzene derivatives (HBD) that have polluted the aquatic environment are bromobenzene and chlorobenzene. Ferrate can degrade various pollutants quickly and efficiently without producing harmful byproducts. This study aims to determine the ability of ferrate to degrade harmful contaminants such as bromobenzene and chlorobenzene. A series of batch experiments were carried out, including for the molar ratio, initial pH solution, and temperature. The study was conducted at an initial pH of 3.6 to 9.6, a molar ratio of 2 to 8 and a temperature of 15 to 55 °C. The study will also examine the differences in functional groups in these pollutants. As a result of the experiments, the optimum conditions to oxidize HBD in a batch reactor was found to have an initial pH of 7.0, a molar ratio of 8, and a temperature of 45 °C, with a 10 min reaction time. Ferrate has a degradation ability against chlorobenzene greater than bromobenzene. The functional cluster in pollutants also significantly affects the degradation ability of ferrate. The results of the degradation experiment showed that ferrate(VI) could effectively oxidize hazardous benzene derivatives in a solution.

High-strength Ti2AlN ceramics prepared by pulse electric current sintering based on powders synthesized by molten salt method

Ti2AlN powders were synthesized through molten salt method and re-calcination process using TiH2, Al and TiN powders as raw materials at 1100 ℃. The composition of final composite was directly influenced by the initial Al and TiH2 content in the starting mixture. The purity of the synthesized Ti2AlN powder could reach 97.1 wt% when the Al molar ratio was 1.05. Then high strength Ti2AlN ceramics were successfully prepared in different modes, including two forms of pulse electric current sintering (PECS/SPS) and hot-pressing sintering (HP). A record-high flexural strength of 719 MPa was obtained for the PECS/SPS with an electrical insulating die (PECS/SPS II) sintered sample, based on the synthesized powder in which the initial molar ratio of Al was 1.1. The sintering behaviors in various modes were analyzed, confirming the shrinkage of particles starting at lower temperature in PECS/SPS II. The density, microstructure, Vickers hardness and elastic modulus of sintered ceramics were also investigated. Therefore, the present work provided the new methods about powder preparation and ceramic sintering of Ti2AlN, making it possible to be used as high strength structural ceramics.

Straightforward synthesis of polycarbosilanes from chlorosilanes and chloromethanes by polycondensation using magnesium and titanium(IV) chloride

• Straightforward synthesis of polycarbosilanes (PCS) • TiCl 4 -catalyzed polycondensation in the presence of magnesium. • Thorough analysis of polymerization mechanism. The straightforward synthesis of polycarbosilanes (PCS) was achieved via the polycondensation of chlorosilanes and chloromethanes using magnesium (Mg) and titanium(IV) tetrachloride (TiCl 4 ). In this polycondensation, TiCl 4 acts as an efficient catalyst and the combined use of Mg and TiCl 4 is necessary to produce PCS. The resulting PCS are viscous colored oils that are soluble in organic solvents. The number-average molar mass ( M n ; 1.0–1.5 kg mol −1 ) and molar-mass dispersity ( Ð M ; 1.3–1.9) values of the resulting PCS were determined by size-exclusion chromatography (SEC) using polystyrene standards. The 1 H, 13 C{ 1 H}, and 29 Si{ 1 H} NMR as well as IR spectra of the resulting PCS revealed that they consist of Si–C, Si–H, Si(H)–H, C–C, and Si–Si bonds. The structures of the resulting PCS vary depending on the structures of the monomers and their initial molar ratios. The ceramic yields from the obtained PCS (23–70%) depend on the original structures of the PCS. A plausible mechanism of this polycondensation is proposed based on the results of polycondensations and model reactions.

Biodiesel (methyl oleate) synthesis in the presence of pyridinium and aminotriazolium acidic ionic liquids: Kinetic, thermodynamic studies

Kinetics and thermodynamics of biodiesel (methyl oleate) synthesis using the protic ionic liquids pyridinium hydrogen sulfate (PHS), pyridinium nitrate (PN) and 4-amino-1H-1,2,4-triazolium nitrate (ATN) as catalysts are studied in the current work for the first time. Rate of the biodiesel production is directly related to acidity of the ionic liquids used and their internal hydrogen bonding extent. A detailed thermodynamic analysis on the title reaction is conducted as well. To optimize the reaction conditions, influence of the reaction temperature (25–55 °C), initial alcohol-to-acid molar ratio (1.0–15.0) and catalyst loading (5–15 wt% with respect to the substrate mass) is investigated in details. Catalyst reusability is evaluated for five cycles. Based on the experimental data, a plausible mechanism of biodiesel synthesis is offered. Catalytic performance of the PHS sample in the biodiesel synthesis is remarkably higher than that of the nitrate anion-based ionic liquids. Reaction temperature of 55 °C, an initial reactants molar ratio of 7.0 and a catalyst loading of 10 wt% are established as optimal conditions for the process of biodiesel production. Values of 43.09 kJ/mol and 91.29 × 105 l/mol × min are calculated as activation energy and pre-exponential factor, respectively. ΔSr° and ΔHr° for the process of biodiesel synthesis are found to be 42.32 J/mol × K and 9.64 kJ/mol, respectively. Moreover, ΔH≠ (40.49 kJ/mol) and ΔS≠ (−162.31 J/mol × K) are established as well. The respective ΔGr° (−4.241 kJ/mol) and ΔG≠ (93.727 kJ/mol) at reaction temperature of 55 °C are obtained.

Continuous synthesis of isobutylaluminoxanes in a compact and integrated approach

We present a 3D-printed continuous flow platform for controllable synthesis of isobutylaluminoxanes (IBAO), an effective olefin polymerization co-catalyst, via the highly exothermic hydrolytic reaction of triisobutylaluminum (TIBA). This platform encompasses modules of mixing and reaction, in-line separation, and in situ UV–vis characterization. In addition, two NMR protocols are established to validate the results of in-line UV–vis analysis (by 31P NMR) and reveal product structures (by 1H NMR). Measured temperature profiles over the reactor indicate essentially fast heat removal, ensuring inherent safety. Co-catalytic activities of IBAO are obtained from ethylene oligomerization experiments using an iron-based catalyst system at atmospheric pressure. Furthermore, we investigate the influence of key operating parameters including temperature, initial molar ratio between water and TIBA, initial TIBA concentration, and residence time. A high IBAO yield over 98% and a superior co-catalytic activity of ~ 5000 kg·(mol Fe)–1·h−1 are achieved with optimal parameters in this single-pass platform, demonstrating the advantages of process.

Synthesis and characterization of two new molten acid salts: Safe and greener alternatives to sulfuric acid for the hydrolytic conversion of 1,1,1,3-tetrachloro-3-phenylpropane to cinnamic acid

Available online Two new acid salts were synthesized, and their chemical structures were characterized by various spectra data analyses. Although 1H NMR did not show acid proton of [HSO4]−, the FTIR spectra of molten acid salts act as key support to approve of their chemical structures. The structure elucidation of the molten acid salts demonstrated the existence of 4,4ʹ-trimethylene-N,Nʹ-dipiperidinium dication with sulfate and hydrogen sulfate anion(s). Thus, sulfuric acid can act as a diprotic or monoprotic Brönsted acid when it is treated by a secondary amine regarding the initial mole ratio of sulfuric acid and amine. Also, the catalytic activity of these molten acid salts was investigated for the hydrolytic conversion of (1,3,3,3-tetrachloropropyl)benzene to cinnamic acid. The desired product was obtained in 88 ± 2.0% yield under optimal conditions. The molten acid salts were high recyclable and their chemical structure and catalytic efficiency showed no significant change even after the 5th run. Furthermore, TMDP-SA (1:1) showed a much weaker corrosive property compared with TMDP-SA (1:2) and SA (98%), and the surface of stainless steel was intact even after 24 h. This fact and the acidity of two molten acid salts also confirm the proposed chemical structures.

Water-Dispersible Fe3O4 Nanoparticles Modified with Controlled Numbers of Carboxyl Moieties for Magnetic Induction Heating

Monodisperse Fe3O4 nanoparticles (NPs) with excellent water dispersibility and stability were prepared by the introduction of the carboxyl group (−COOH) on the surface of the as-prepared oleyl-capped Fe3O4 NPs. Controlled introduction of the COOH moieties on the NP surface was carried out by a simple ligand exchange reaction using two types of phosphonic acid ligands with dodecyl moiety and the terminal COOH group. The degree of modification of the COOH group on the particle surface was controlled by tuning the molar ratios of the two phosphonic acids. During the ligand exchange reaction, no change was observed in the crystal structure and morphology of the Fe3O4 NPs. The results of Fourier transform infrared (FT-IR) spectroscopy confirmed that the two ligands were bound to the Fe3O4 NP surface through their phosphoric acid functional groups. The surface coverage and molar ratios of the two ligands were evaluated by thermal gravimetric analysis (TGA) and via proton nuclear magnetic resonance (1H NMR) measurements, respectively. Results obtained from the thermal analyses were consistent with the initial molar ratios of the ligands used in the reaction, which reflect on the efficiency of the developed ligand exchange process. Our COOH-modified Fe3O4 NPs could be dispersed in water by deprotonation for over 6 months and exhibit a typical ferrofluid behavior without the addition of other surfactants and dispersants, showing high dispersion stability. Furthermore, the magnetic induction heating performance of the Fe3O4 NPs in aqueous dispersions was evaluated and the specific absorption rate (SAR) value was estimated to be 38.3 W/g Fe. These results suggest that our COOH-modified Fe3O4 NPs with the desired number of COOH surface moieties can be advantageous for applications such as precise surface design, water-based ferrofluid, and hyperthermia treatment.

Facile fabrication of Fe-BDC/Fe-2MI heterojunction with boosted photocatalytic activity for Cr(VI) reduction

Novel Fe-BDC/Fe-2MI heterojunction (H2BDC: terephthalic acid, 2MI: 2-methylimidazole) was prepared via a one-pot solvothermal method. Herein, mixed ligands (H2BDC and 2MI) was applied to form complex with Fe(III). Interestingly, the presence of 2MI can regulate the structure of Fe-BDC. Spindle-like MIL-88B(Fe) was observed in Fe-BDC/Fe-2MI composite, while MIL-53(Fe) was identified in naked Fe-BDC. By employing photoelectrochemical characterizations, Fe-BDC/Fe-2MI was optimized at an initial molar ratio of 1:0.5:10 for Fe(III):H2BDC:2MI, which exhibited the highest photocurrent response, lowest charge transfer resistance, and fastest surface reaction kinetics as compared to the individual Fe-BDC and Fe-2MI. Due to the formation of the heterojunction which lead to beneficial photoelectrochemical properties, the as-prepared samples exhibited boosted photocatalytic activity for Cr(VI) reduction. The calculated pseudo-first-order rate constant (k) was 0.046 min−1 for Fe-BDC/Fe-2MI, which was 15.3 and 6.6 times that of Fe-BDC (0.003 min−1) and Fe-2MI (0.007 min−1), respectively. Moreover, the optimized Fe-BDC/Fe-2MI demonstrated superior performance with negligible loss in activity after 4 cyclic runs.

Optimization and green metrics analysis of the liquid-phase synthesis of sec-butyl levulinate by esterification of levulinic acid with 1-butene over ion-exchange resins

Liquid-phase esterification of levulinic acid (LA) with 1-butene (1B) over ion-exchange resins was studied following an experimental design approach aimed at identifying the optimal conditions to synthesize sec-butyl levulinate (SBL) through the proposed reaction pathway. Experiments were performed in a temperature range of 313–383 K with initial molar ratios of LA to 1B (R°LA/1B) from 0.4 to 3. The optimal experimental conditions determined at 373 K and R°LA/1B = 0.5 render 1B and LA yields to SBL of 48.1% and 76.8%, respectively. Empirical equations relating conditions and yields were obtained, and response surface methodology analysis with subsequent multiobjective optimization allowed identification of optimal conditions to maximize simultaneously the yield of both reactants to SBL—that is high 1B initial concentration and temperature ranging 360–370 K. According to screening experiments, dense polymer network favors SBL formation. Amberlyst™15 was the most promising catalyst among the tested ones, since it yields the highest conversion with very low side reactions extension. A green metrics analysis was performed to ascertain the sustainability of the proposed chemical route and to compare it with previously reported studies for the SBL synthesis. Among the scenarios assessed, the proposed chemical pathway represents the greenest alternative.

Water absorption and compressive strength of various coal fly ash-based geopolymer pastes

This paper discusses the effects of the silicon dioxide to aluminium oxide molar ratio, sodium oxide to aluminium oxide molar ratio and concentration of sodium hydroxide on the water absorption and compressive strength of synthesised fly ash-based geopolymers. Geopolymer pastes were prepared using fly ash mixed with an alkaline activator consisting of sodium hydroxide solution and sodium silicate solution. The phase composition, microstructure and chemical bonding of the synthesised products were characterised after 7 and 28 days using X-ray diffraction, scanning electron microscopy and Fourier-transform infrared spectroscopy, respectively. The synthesised geopolymer with a silicon dioxide to aluminium oxide molar ratio of 5 and a sodium oxide to aluminium oxide molar ratio of 1.2, activated with 10 M sodium hydroxide, was found to have the highest strength and the lowest water absorption. The compressive strength was observed to increase with increasing silicon dioxide to aluminium oxide molar ratio. A high initial molar ratio of sodium oxide to aluminium oxide enhances the water absorption and decreases the strength of the geopolymer sample. The dissolution of silica and alumina from the starting materials becomes more efficient as the concentration of sodium hydroxide increases.

Effects of initial SiO2/Al2O3 molar ratio and slag on fly ash-based ambient cured geopolymer properties

Geopolymers cured at ambient temperature are of high interest since they provide promising environmentally friendly alternative to cement. This paper discusses the effect of the initial molar ratio of SiO2/Al2O3 and fly ash replacement with ground granulated blast furnace slag (GGBFS) on the properties of fly ash-based geopolymers. Geopolymer mixtures developed in this study are user-friendly (SiO2/Na2O larger than 1.4) and suitable for producing self-compacting geopolymer concrete at ambient temperature. Results showed that the increase in SiO2/Al2O3 ratio accelerated the setting of fly ash-slag geopolymer systems, which was quite different from that reported for metakaolin-based geopolymers. An increasing–decreasing trend in compressive strength was observed by increasing the SiO2/Al2O3 ratio. The maximum compressive strength achieved when the SiO2/Al2O3 ratio was 3.37 (Si/Al = 1.68). The higher compressive strength at this ratio could be related to the alumina-silica bondings in the amorphous area, which comprised more than 81%-84% of geopolymer microstructure. Furthermore, the study revealed that the decrease in fly ash replacement with GGBFS prolonged the setting of geopolymer mixtures and reduced their compressive strength significantly.

Copper Tricomponent Catalysts Application for Hydrogen Production from Ethanol

The application of copper-based catalysts in the production of pure hydrogen in the steam reforming of ethanol was performed. The tricomponent Cu/Zr catalysts with about 4 mass% addition of nickel, cobalt, or cerium have been prepared in our laboratory. The properties of obtained catalysts were compared with bimetallic Cu/Zr catalyst prepared and tested according to the same procedure. Catalytic tests were carried out in the continuous flow fixed–bed reactor in the wide temperature range of 433–593 K for initial molar ratio of ethanol to water equal to 1:3. Catalysts were characterized by XRD, TPR, CO2–TPD, and TPO methods. Cu/Zr/Ce catalyst proved to be the best; hydrogen yield reached the value of 400 L/(kgcat.∙h), selectivity towards carbon monoxide was below 0.5% and the one towards methane wasnot detected. Additions of Ni or Co did not bring significant improvement in activity.

Kinetics Study of the Esterification Reaction of Cyclohexene to Cyclohexyl Acetate Catalyzed by Novel Brønsted–Lewis Acids Bifunctionalized Heteropolyacid Based Ionic Liquids Hybrid Solid Acid Catalysts

A series of Bronsted–Lewis acids bifunctionalized heteropolyacid based ionic liquids hybrid solid acid catalysts (BLA-HPA-ILs) were synthesized by combining the Bronsted acidic ionic liquid [Bis–Bs–BDMAEE]HPW12O40 with metallic oxide in different composition ratios and applied in the esterification of cyclohexene to cyclohexyl acetate. Among the synthesized catalysts, the 1/2Cu[Bis–Bs–BDMAEE]HPW12O40 catalyst with Bronsted and Lewis acidities shown the most excellent catalytic performance for the esterification of cyclohexene with acetic acid. The BLA-HPA-ILs catalysts were characterized by elemental analysis, FT-IR, Py-IR, TG, 1H NMR, SEM and EDX. The effects of reaction temperature, catalyst dosage, and initial reactant molar ratio has been investigated in detail. A pseudohomogeneous (PH) kinetic model was used to correlate the kinetic data in the temperature range of 333.15–363.15 K, and the kinetic parameters were estimated, indicating the results calculated by the kinetic model are well coincidence with the experimental results. Moreover, as a heterogeneous reaction catalyst, 1/2Cu[Bis–Bs–BDMAEE]HPW12O40 could be easily recovered by a simple treatment and reused six times without any obvious decrease in catalytic activity, displaying good reusability.

The nanostructure of rod-like ascorbyl dipalmitate nanoparticles stabilized by a small amount of DSPE-PEG

Previously, we reported the formation of 100–200 nm disk- and tube-like nanoparticles by hydration of L-ascorbyl 2,6-dipalmitate (ASC-DP) and distearoylphosphatidylethanolamine polyethylene glycol 2000 (DSPE-PEG) films prepared at an initial molar ratio of 2:1. This study investigated the feasibility of nanoparticle formation with higher ASC-DP loading. Although particle size distribution determined by dynamic light scattering showed a multimodal pattern including micro-sized particles at a molar ratio of 3:1, the mean particle size gradually decreased with a further increased molar ratio. Homogeneous ca. 240 nm nanoparticles with a unimodal size distribution were obtained at a molar ratio of 10:1. FE-TEM showed that the nanoparticles at a molar ratio of 10:1 were rod-shaped with a diameter of ca. 100 nm and a length of ca. 300 nm. After centrifugation, X-ray analysis of the nanoparticle precipitates showed that these rod-like nanoparticles were composed of a series of lamellar structures with 3.7 nm repeated units. The molar ratio of ASC-DP/DSPE-PEG in the nanoparticle precipitates determined by 1H NMR measurements was 68.8:1. The rod-like nanoparticles should be composed of a core–shell structure, where a small amount of DSPE-PEG covers the lamellar structure of ASC-DP. Further increase in the ASC-DP/DSPE-PEG molar ratio over 33:1 no longer provided nanoparticles. Hence, to prepare a stable ASC-DP nanoparticle suspension, it is necessary to prepare ASC-DP/DSPE-PEG films containing at least 3 mol% DSPE-PEG.

Study of metal-polymer copper nanocomposites using the method of UV spectroscopy

New polymer copper-containing nanocomposites based on poly-N-vinylimidazole were obtained. The formation of nanocomposites was carried out using the method of chemical reduction of copper ions from a solution of copper acetate with ascorbic acid in an aqueous medium in the presence of a polymer. Nanocomposites were prepared at the polymer:Cu (II) molar ratio of 10:1 and 5:1. The reduction reaction yielded powder nanocomposites of a red-brown colour and having a metallic shine. It was found that the content of copper in the obtained nanocomposites depends on the initial molar ratio of the stabilising poly-N-vinylimidazole and Cu (II), reaching 5.9% and 11.7%. The formation of nanosized copper particles was investigated and confirmed by UV spectroscopy. The optical spectra of aqueous solutions of the obtained copper-containing nanocomposites contained maxima at 537–541 and 646–651 nm, which confirmed the formation of ultradispersed copper in the nanosized state. The obtained copper-containing nanocomposites based on poly-N-vinylimidazole are promising materials for use in medicine and catalysis, as well as in optical, sensor and electronic devices.

Fe2+/H2O2-Strengite method with the enhanced settlement for phosphorus removal and recovery from pharmaceutical effluents

Phosphorus excessively discharged into the water body is a primary cause of eutrophication, but phosphorus resource is limited and non-renewable. If phosphorus could be recovered from wastewaters, it can not only prevent phosphorus pollution but also achieve the recycling of phosphorus resources. This work proposed a novel strategy, Fe2+/H2O2-strengite method with the enhanced settlement, for phosphorus removal and recovery from pharmaceutical wastewater containing organic phosphorus (OP). In this scheme, OP could be converted into inorganic phosphorus (IP) in the Fe2+/H2O2 oxidation system, and then IP was recovered in the strengite system. This approach possessed the advantages of simple operation, high efficiency and valuable recovery products, besides, reducing the consumption of reagents, and hardly resulting in secondary pollution. Sixty cycles of phosphorus removal and recovery experiments were conducted, in which pH value was 4 and the initial molar ratio of Fe/P was 1.5. This process achieved a satisfactory and steady phosphorus removal performance, with soluble phosphate and total phosphorus removal efficiencies of 95.3% ± 1.7% and 91.4% ± 2.5%, respectively, and phosphorus was recovered. Possible mechanisms involved: the formation of amorphous strengite (FePO4·2H2O) analogue, the adsorption of hydrous ferric oxide (HFO) to phosphorus, and the flocculation of ferric salts. Besides, the presence of quartz as carriers could enhance the settling efficiency of products. Also, via various characterizations, products included amorphous strengite analogue and goethite mixed with phosphorus. This work provided an effective method to reduce OP pollution and recover phosphorus, and supplied thoughts for the treatment of refractory pollutants and the recycling of limited resources.

Molybdenum-Tungsten Blue Nanoparticles as a Precursor for Ultrafine Binary Carbides.

Herein, we demonstrate a promising method for the synthesis of ultrafine carbide particles using dispersions of molybdenum–tungsten nanoparticles. Dispersions of molybdenum–tungsten blue nanoparticles with different initial molar ratios of molybdenum/tungsten were synthesized through the reduction of molybdate and tungstate ions by ascorbic acid in an acidic medium (pH = 1.0–2.5). Molybdenum–tungsten blue nanoparticles were characterized by ultraviolet–visual (UV–VIS), infrared (FTIR), and X-ray photoelectron (XPS) spectroscopies; transmission electronic microscopy (TEM); and dynamic light scattering (DLS). We demonstrated that molybdenum–tungsten blue nanoparticles belong to toroidal polyoxometalate clusters (λmax = 680–750 nm) with a predominant particle size of 4.0 nm. Molybdenum–tungsten blue dispersions were shown to be monodispersed systems with a small particle size and long-term stability (>30 days) and are suitable for further catalytic applications.

Gallic Acid/2-Hydroxypropyl-β-cyclodextrin Inclusion Complexes Electrospun Nanofibrous Webs: Fast Dissolution, Improved Aqueous Solubility and Antioxidant Property of Gallic Acid

Gallic acid(GA) is a kind of natural polyphenolic compound, but its low aqueous solubility restricts its application in the fields of food and medicine. Cyclodextrin can form inclusion complexes with guest molecules(e.g., essential oils, food supplements) through cavities with special properties to improve aqueous solubility, thermal stability, and bioavailability of guest molecules. In this research, gallic acid/2-hydroxypropyl-β-cyclodextrin inclusion complexes(GA/2-HP-β-CD/ICs) were formed in a highly concentrated solution of 2-HP-β-CD. Bead-free and uniform nanofibrous webs(GA/2-HP-β-CD/IC-NWs) were produced successfully by electrospun GA/HP-β-CD/IC aqueous solution. The initial molar ratio(GA: 2-HP-β-CD=1:1) of GA/2-HP-β-CD/IC in the solutions was largely maintained in GA/2-HP-β-CD/IC-NW. The aqueous solubility of GA was enhanced and GA/2-HP-β-CD/IC-NW has displayed fast dissolution property. Furthermore, in comparison with GA powder, GA/2-HP-β-CD/IC-NW demonstrated improved antioxidant capacity. The results suggested that GA/2-HP-β-CD/IC-NW have broad application prospects as orally fast dissolution systems for food supplements.