Formation and Extractive Desulfurization Mechanisms of Aromatic Acid Based Deep Eutectic Solvents: An Experimental and Theoretical Study.

The formation and extractive desulfurization (EDS) mechanisms of aromatic acid based deep eutectic solvents (DESs) were studied experimentally and through quantum chemistry calculations. Hydrogen bonding and van der Waals forces were investigated as the driving forces for the formation of aromatic acid based DESs by means of 1 H NMR and FTIR spectroscopy, and DFT calculations. The driving forces of EDS were also studied. The results showed that van der Waals forces and other weak interactions were the main diving forces for EDS, and the structures of the aromatic acid based DESs did not change after EDS. The interaction energy between the aromatic acid based DESs and thiophene (TH), benzothiophene (BT), and dibenzothiophene (DBT) were calculated by DFT to understand the EDS order: TH

Deep oxidative desulfurization of dibenzothiophene in simulated oil and real diesel using heteropolyanion-substituted hydrotalcite-like compounds as catalysts.

Three heteropolyanion substituted hydrotalcite-like compounds (HPA-HTLcs) including Mg9Al3(OH)24[PW12O40](MgAl-PW12), Mg9Al3(OH)24[PMo12O40] (MgAl-PMo12) and Mg12Al4(OH)32[SiW12O40] (MgAl-SiW12), were synthesized, characterized and used as catalysts for the oxidative desulfurization of simulated oil (dibenzothiophene, DBT, in n-octane). MgAl-PMo12 was identified as an effective catalyst for the oxidative removal of DBT under very mild conditions of atmospheric pressure and 60 °C in a biphasic system using hydrogen peroxide as oxidant and acetonitrile as extractant. The conversion of DBT was nearly 100%. As a result, because of the influence of the electron density and the space steric hindrance, the oxidation reactivity of the different sulfur compounds in simulated oil followed the order DBT > 4,6-dimethyldibenzothiophene (4,6-DMDBT) > benzothiophene (BT) > thiophene (TH). When the reaction is finished, the catalysts can be recovered from the acetonitrile phase by filtration. The recovered MgAl-PMo12 retains nearly the same catalytic activity as the fresh material. Moreover, MgAl-PMo12 was found to exhibit an ideal catalytic activity in the oxidative desulfurization of real diesel resulting in a total remaining sulfur content of 9.12 ppm(w).

A ductile and strong-affinity network binder coupling inorganic oligomers and biopolymers for high-loading lithium-sulfur batteries.

Lithium sulfur (Li-S) batteries have become the predominant energy storage devices of the future. However, the reasons why Li-S batteries have not been widely commercialized include the shuttle effect of polysulfides and the volume expansion of sulfur active substances. In this study, a binder with a stretchable 3D reticular structure was induced using inorganic oligomers. Potassium tripolyphosphate (PTP) has been used to powerfully connect the tamarind seed gum (TSG) chain through robust intermolecular forces due to the strong electronegativity of P-O- groups. With this binder, the volume expansion of sulfur active substances can be well restrained. In addition, a large amount of -OH groups in TSG and P-O- bonds in PTP can also effectively adsorb polysulfides and inhibit the shuttle effect. Therefore, the S@TSG-PTP electrode shows an improved cycle performance. When the sulfur loading is as high as 4.29 mg cm-2, the areal specific capacity can reach 3.37 mA h cm-2 after 70 cycles. This study highlights a new way for the binder design of high-loading sulfur electrodes.

Ru-Ni Alloy Nanoparticles Loaded on N-Doped Amphiphilic Mesoporous Hollow Carbon@silica Spheres as Catalyst for the Hydrogenation of α-Pinene to cis-Pinane.

N-doped mesoporous carbon spheres (NHMC@mSiO2 ) encapsulated in silica shells were prepared by emulsion polymerization and domain-limited carbonization using ethylenediamine as the nitrogen source, and Ru-Ni alloy catalysts were prepared for the hydrogenation of α-pinene in the aqueous phase. The internal cavities of this nanomaterial are lipophilic, enhancing mass transfer and enrichment of the reactants, and the hydrophilic silica shell enhances the dispersion of the catalyst in water. N-doping allows more catalytically active metal particles to be anchored to the amphiphilic carrier, enhancing its catalytic activity and stability. In addition, a synergistic effect between Ru and Ni significantly enhances the catalytic activity. The factors influencing the hydrogenation of α-pinene were investigated, and the optimum reaction conditions were determined to be as follows: 100 °C, 1.0 MPa H2 , 3 h. The high stability and recyclability of the Ru-Ni alloy catalyst were demonstrated through cycling experiments.

Unique Cd0.5Zn0.5S/WO3-x direct Z-scheme heterojunction with S, O vacancies and twinning superlattices for efficient photocatalytic water-splitting.

Photocatalytic water-splitting employing the Z-scheme semiconductor systems mimicking natural photosynthesis is regarded as a promising way to achieve efficient soalr-to-H2 conversion. Nevertheless, it still remains a big challenge to design high-performance direct Z-scheme photocatalysts without the use of noble metals as electron mediators. Herein, a unique Cd0.5Zn0.5S/WO3-x direct Z-scheme heterojunction was constructed for the first time, which consisted of smaller O-vacancy-decorated WO3-x nanocrystals anchoring on Cd0.5Zn0.5S nanocrystals with S vacancies and zinc blende/wurtzite (ZB/WZ) twinning superlattices. Under visible-light (λ > 420 nm) irradiation, the Cd0.5Zn0.5S/WO3-x composites exhibited an outstanding H2 evolution reaction (HER) activity of 20.50 mmol h-1 g-1 (corresponding to the apparent quantum efficiency of 18.0% at 420 nm), which is much superior to that of WO3-x, Cd0.5Zn0.5S, and Cd0.5Zn0.5S loaded with Pt. Interestingly, the introduced O and S vacancies contributed to improving the HER activity of Cd0.5Zn0.5S/WO3-x significantly. Moreover, the cycling and long-term HER measurements confirmed the robust photocatalytic stability of Cd0.5Zn0.5S/WO3-x for H2 production. The excellent light harvesting and efficient spatial charge separation induced by the ZB/WZ twinning homojunctions and defect-promoted direct Z-scheme charge-transfer pathway are responsible for the exceptional HER capability. Our study could enlighten the rational engineering and optimization of semiconductor nanostructures for energy and environmental applications.

Oxidation of 1-propanol to propionic acid with hydrogen peroxide catalysed by heteropolyoxometalates.

BACKGROUND: Propionic acid as a very valuable chemical is in high demand, and it is industrially produced via the oxo-synthesis of ethylene or ethyl alcohol and via the oxidation of propionaldehyde with oxygen. It is urgent to discover a new preparation method for propionic acid via a green route. Recyclable amino-acid-based organic-inorganic heteropolyoxometalates were first used to high-efficiently catalyse the selective oxidation of 1-propanol to propionic acid with H2O2 as an oxidant. RESULT: A series of amino-acid-based heteropoly catalysts using different types of amino acids and heteropoly acids were synthesized, and the experimental results showed proline-based heteropolyphosphatotungstate (ProH)3[PW12O40] exhibited excellent catalytic activity for the selective catalytic oxidation of 1-propanol to propionic acid owing to its high capacity as an oxygen transfer agent and suitable acidity. Under optimized reaction conditions, the conversion of 1-propanol and the selectivity of propionic acid reached 88% and 75%, respectively. Over four cycles, the conversion remained at >80%, and the selectivity was >60%. (ProH)3[PW12O40] was also used to catalyse the oxidations of 1-butanol, 1-pentanol, 1-hexanol, and benzyl alcohol. All the reactions had high conversions, with the corresponding acids being the primary oxidation product. CONCLUSIONS: Proline-based heteropolyoxometalate (ProH)3[PW12O40] has been successfully used to catalyse the selective oxidation of primary alcohols to the corresponding carboxylic acids with H2O2 as the oxidant. The new developed catalytic oxidation system is mild, high-efficient, and reliable. This study provides a potential green route for the preparation propionic acid.

Hydrogenation of α-Pinene over Platinum Nanoparticles Reduced and Stabilized by Sodium Lignosulfonate.

A one-pot clean preparation procedure and catalytic performance of platinum nanoparticles (NPs) reduced and stabilized by sodium lignosulfonate in aqueous solution are reported. No other chemical reagents are needed during the metal reduction and stabilization step, thanks to the active participation of sodium lignosulfonate (SLS). UV-vis, Fourier transform infrared (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), 1H NMR, 195Pt NMR, and two-dimensional heteronuclear single-quantum coherence (2D HSQC) NMR studies were thoroughly performed to analyze the formation, particle size, and main lattice planes of NPs, the valence-state changes of the metal, and structural changes of SLS. An ecofriendly selective synthesis of cis-pinane from an abundant renewable natural resource, α-pinene, was developed in the presence of the prepared Pt NP aqueous system. Furthermore, this catalyst system was proved to show easy recovery and stable reusability by five-run tests. The synergistic effect of SLS reduction and stabilization not only avoided the introduction of conventional reducing agents and stabilizers but also made full use of the byproducts of the pulp and paper industry. This proved to be an environmentally friendly method for converting the natural resource α-pinene to cis-pinane.

Differential activity of the antioxidant defence system and alterations in the accumulation of osmolyte and reactive oxygen species under drought stress and recovery in rice (Oryza sativa L.) tillering.

The objective of this study was to investigate the effects of drought stress on the activity of antioxidant enzymes and osmotic adjustment substance content in the tillering period of drought-sensitive and drought-tolerant rice cultivars. The results showed that the superoxide dismutase (SOD), peroxidase (POD), catalase activity (CAT), hydrogen peroxide content, soluble protein content and soluble sugar content increased with the accumulation of time and intensity of drought stress. Compared with the drought-sensitive cultivar, drought-resistant cultivar had a smaller photosynthetic affected area, longer CAT enzyme activity duration, and lower H2O2 accumulation. Unlike POD and CAT enzymes, which maintain the ability to scavenge hydrogen peroxide under long drought conditions, ascorbate peroxidase (APX) enzymes seem to be a rapid response mechanism to scavenge hydrogen peroxide under drought stress. Under a -10 kPa water potential, using soluble sugars on the osmotic adjustment ability of the drought-resistant cultivars was more efficient; under -40 kPa water potential, drought-resistant cultivars can maintain relative high levels of ascorbate (ASA) content in the short term. After the restoration of irrigation, the indices gradually returned to control levels. The ASA content showed faster accumulation ability in drought-resistant cultivars and faster recovery. The soluble protein content recovered more slowly in drought-sensitive cultivars under the -40 kPa treatment. Drought-resistant cultivars showed stronger resistance to drought in the -10 kPa treatment and obtained similar yield to the control, while the drought-sensitive cultivars were more obviously affected by the drought stress.

Alkylation of isobutane and isobutene catalyzed by trifluoromethanesulfonic acid-taurine deep eutectic solvents in polyethylene glycol.

Conventional acidic catalysts for isobutane and isobutene alkylation exhibit low alkylate selectivity. Herein, we employed an acidic deep eutectic solvent, consisting of trifluoromethanesulfonic acid and taurine, in polyethylene glycol as the catalyst. Its high conversion rate and selectivity, as well as recyclability, make it suitable for alkylate gasoline preparation.

Study of catalytic ozonation for tetracycline hydrochloride degradation in water by silicate ore supported Co3O4.

Tetracycline hydrochloride (TCH) degradation by cobalt modified silicate ore (CoSO) catalytic ozonation in aqueous solution was investigated. CoSO catalyst was synthesized by an impregnation method using Co(NO3)2 as the precursor and natural silicon ore (SO) as the support. The key catalyst preparation conditions (i.e., impregnation concentration, calcination temperature and time) were optimized. The activity and stability of CoSO catalyst and its catalytic ozonation mechanism for TCH degradation were studied. The results showed that Co3O4 was successfully coated on the silicon ore and the CoSO catalyst was highly efficient in catalytic ozonation for TCH degradation. The TCH removal by CoSO/O3 could reach 93.2%, while only 69.3% by SO/O3 and only 46.0% by O3 alone at 25 min. The reaction of TCH degradation followed pseudo-first order kinetics. TOC removal rate by CoSO/O3 was 2.0 times higher than that by SO/O3, and 3.5 times higher than that by O3 alone. The reaction conditions (TCH initial concentration, catalyst concentration, pH and temperature) for catalytic ozonation were systematically investigated. The possible mechanism for the CoSO catalytic ozonation process was proposed, where hydroxyl radical oxidation mainly accounted for the substantial TCH degradation. Furthermore, CoSO showed great durability and stability after seven reaction cycles.

Isobutane/2-butene alkylation catalyzed by Brønsted-Lewis acidic ionic liquids.

The alkylation reaction of isobutane with 2-butene to yield C8-alkylates was performed using Brønsted-Lewis acidic ionic liquids (ILs) comprising various metal chlorides (ZnCl2, FeCl2, FeCl3, CuCl2, CuCl, and AlCl3) on the anion. IL 1-(3-sulfonic acid)-propyl-3-methylimidazolium chlorozincinate [HO3S-(CH2)3-mim]Cl-ZnCl2 (x=0.67) exhibited outstanding catalytic performance, which is attributed to the appropriate acidity, the synergistic effect originating from its double acidic sites and the promoting effect of water on the formation and transfer of protons. The Lewis acidic strength of IL played an important role in improving IL catalytic performance. A 100% conversion of 2-butene with 85.8% selectivity for C8-alkylate was obtained under mild reaction conditions. The IL reusability was good because its alkyl sulfonic acid group being tethered covalently, its anion [Zn2Cl5]- inertia to the active hydrogen, and its insolubility in the product. IL [HO3S-(CH2)3-mim]Cl-ZnCl2 had potential applicability in the benzene alkylation reaction with olefins and halohydrocarbons.

Cyanidophenyl-tris(trimethyl-phosphine)cobalt(II).

The title mol-ecule, [Co(C(6)H(5))(CN)(C(3)H(9)P)(3)], lies on a crystallographic mirror plane with the Co(II) ion coordinated in a distorted square-pyramidal environment with one of the P atoms in the apical position. In the basal plane, the phenyl substituent is trans to the cyanide group with a C-Co-C angle which is significantly distorted from linearity.

Grape seed proanthocyanidins induce mitochondrial pathway-mediated apoptosis in human colorectal carcinoma cells.

Grape seed proanthocyanidins (GSPs) have been reported to possess a wide array of pharmacological and biochemical properties. Recently, GSPs have been reported to inhibit various types of colorectal cancer; however, the mechanism(s) involved remain unclear. The present study investigated the effects of GSPs on HCT-116 human colorectal carcinoma cell line. Exposure of these cells to GSPs for 48 h resulted in a significant concentration-dependent inhibition of cell viability. Further investigation indicated that GSPs induced apoptosis of these cells. Analyses of mRNA expression levels using reverse transcription-quantitative polymerase chain reaction and protein expression levels by western blotting revealed that this was associated with increased expression levels of p53 tumor suppressor protein, cytochrome c, and pro-apoptotic proteins, apoptosis regulator Bax (Bax) and Bcl-2 homologous antagonist/killer. Furthermore, decreased expression levels of the anti-apoptotic protein, B cell lymphoma-2 and activation of caspase-2, caspase-3 and caspase-9 were demonstrated. GSP-induced loss of mitochondrial membrane potential was also detected by JC-1 assay. These findings suggested that GSPs induced colon cancer cell apoptosis via the mitochondrial signaling pathway. This provided evidence indicating that GSPs may provide potential chemotherapeutic agents for colorectal cancer.

A novel Brönsted-Lewis acidic heteropoly organic-inorganic salt: preparation and catalysis for rosin dimerization.

A novel Brönsted-Lewis acidic heteropoly organic-inorganic salt has been prepared via the replacement of protons in neat phosphotungstic acid with both organic and metal cations. This hybrid catalyst, Sm0.33[TEAPS]2PW12O40, exhibited satisfactory performance in the dimerization of rosin to prepare polymerized rosin Under optimum conditions (15.0 g rosin and 5.0 g Sm0.33[TEAPS]2PW12O40 catalyst in 18.0 mL toluene at 90 °C for 10 h), a polymerized rosin product with a softening point of 120.1 °C was obtained. In addition, the Sm0.33[TEAPS]2PW12O40 catalyst maintains excellent catalytic performance over five recycles.

Electrochemical detection of DNA hybridization based on signal DNA probe modified with Au and apoferritin nanoparticles.

A novel and ultrasensitive electrochemical approach for sequence-specific DNA detection based on signal dual-amplification with Au NPs and marker-loaded apoferritin NPs was reported. Target DNA was sandwiched between capture DNA coupled to magnetic beads and signal DNA self-assembled on Au NPs which were incorporated with marker-loaded apoferritin NPs. Subsequent electrochemical stripping analysis of the electroactive markers released from apoferritin NPs in acidic buffers provided a means to quantify the concentration of target DNA. In this means, one target signal could be transformed into multiple redox signals of the markers since a single Au NP could be loaded with dozens of apoferritin NPs, and an apoferritin NP could be loaded with thousands of markers. Under the optimum conditions, the linear range was from 2.0 × 10(-16) to 1.0 × 10(-14)M and the detection limit was 5.1 × 10(-17)M by using the cadmium as a model marker. The proposed DNA biosensor not only exhibited excellent sensitivity but also had good reproducibility and selectivity against two-base mismatched DNA.

Investigation of voltammetric enzyme-linked immunoassay system based on N-heterocyclic substrate of 2,3-diaminopyridine.

A new voltammetric enzyme-linked immunoassay system using the electrochemical substrate 2,3-diaminopyridine (DAP) and horseradish peroxidase (HRP) system has been developed. DAP is oxidized with H2O2 catalyzed by HRP, and the resulting electroactive product produces a sensitive voltammetric peak at potential of -0.72V (vs. saturated calomel electrode (SCE)) in Britton-Robinson (BR) buffer solutions. The enzyme-catalyzed reaction conditions and voltammetric detection conditions have been investigated in detail. Under the selected optimum conditions, the linear range for detection of free HRP is from 6.0 x 10(-11) to 1.0 x 10(-8) g mL(-1) with a detection limit of 1.0 x 10(-12) g mL(-1). The new voltammetric detection system has been successfully applied for the assay of prostate specific antigen (PSA) in human serum ranging from 0.4 to 100 ng mL(-1) with a detection limit of 0.1 ng mL(-1), which is five times lower than that of traditional o-phenylenediamine (OPD) spectrophotometric enzyme-linked immunosorbent assay (ELISA) method. The proposed N-heterocyclic electrochemical detection system of DAP-H2O2-HRP has provided a new and much improved immunoassay method.

Investigation of voltammetric enzyme-linked immunoassay based on a new system of HAP-H2O2-HRP.

By introducing heterocyclic compound to immunoassay system as an electrochemical substrate for the fist time, a new voltammetric enzyme-linked immunoassay system of 3-hydroxyl-2-aminopyridine (HAP)-H(2)O(2)-horseradish peroxidase (HRP) has been developed. HAP was oxidized with H(2)O(2) catalyzed by HRP, and the resulting electroactive product produced a sensitive voltammetric peak at potential of -0.36 V (vs. SCE) in Britton-Robinson (BR) buffer solution. The process of the enzyme-catalyzed reaction and the electro-reduction of the product have been investigated in detail. The linear range for detection of free HRP was from 4.0x10(-13) to 1.0x10(-9) g/mL with a detection limit of 1.2x10(-13) g/mL. The new system has been successfully applied for the assay of alpha-fetoprotein (alphaFP) in human serum ranging from 0.1 to 200 ng/mL with a detection limit of 0.1 ng/mL, which was 10 times lower than that of traditional spectrophotometric enzyme-linked immunosorbent assay (ELISA) method. HAP-H(2)O(2)-HRP voltammetric enzyme-linked immunoassay showed a promising alternative approach in the detection of alphaFP in clinical diagnosis.