2O Solution Research Articles

Species distribution of CO2 absorption/desorption in aqueous and non-aqueous N-ethylmonoethanolamine solutions

The CO2 absorption and desorption in N-ethylmonoethanolamine (EMEA) solutions were carried out using an absorption−desorption apparatus and the species distribution was explored using the quantitative 13C NMR spectroscopy. EMEA+ethanol solution had a much lower CO2 loading (0.547mol CO2/mol EMEA) than EMEA+H2O solution (0.799mol CO2/mol EMEA) due to the lower concentration of alky carbonate generated in EMEA+ethanol solution than the corresponding bicarbonate/carbonate as generated in EMEA+H2O solution and the no further reaction of carbamate with CO2 in EMEA+ethanol solution. The EMEA regeneration efficiency of the EMEA+ethanol solution at 363, 373 and 383K (55.44, 86.86 and 100.00%) was much higher than EMEA+H2O solution at corresponding temperatures (27.56, 30.25 and 38.80%), which was mainly influenced by the decomposition of carbamate, while the existence of bicarbonate prevented carbamate decomposing.

CO2 Capture Using Absorbents of Mixed Ionic and Amine Solutions

Studies have been conducted to find new absorbents for post-combustion CO2 capture. To overcome the ILs’ limits and meanwhile take their advantages, the mixed amine+IL+H2O solutions as CO2 capture absorbent were investigated in a CO2 absorption/desorption loop setup. It was found that with an increase in IL concentration, the viscosity of the mixed solution rose while the energy required for absorbent regeneration decreased. In addition, no IL loss was detected and the amine loss per ton of captured CO2 was considerably lower than that of aqueous amine solution. The viscosity of the best candidate of 30 wt% MEA+40 wt% [bmim][BF4]+30 wt% H2O is close to the value of aqueous amine solution, indicating that the ionic liquid disadvantage of high viscosity can be overcome for absorbent delivery of CO2 capture.

Synthesis of tetraphenylphosphonium (thio)phosphorylthiobenzamides and hydrolytic degradation to Ph3P=O, H2S and phosphoryl(thio)benzamides: A route for crystal design of PhC(X)NHP(O)(OiPr)2 (X=S, O)

Reactions of the sodium salts of PhC(S)NHP(Y)(OiPr) 2 (Y=S, HL I; O, HL II) with PPh 4Br in 96% aqueous EtOH leads to the corresponding compounds PPh 4L I,II. The structures of these compounds were investigated by IR, 1H, 31P{ 1H} NMR spectroscopies; their compositions were examined by microanalysis. Recrystallization of PPh 4L I,II from EtOH/H 2O solution (1:1, v/v) leads to the formation of HL II and PhC(O)NHP(O)(OiPr) 2 (HL III), respectively. The crystal structures of HL II,III are reported and compared with the previously reported polymorphs. © 2012 Elsevier B.V. All rights reserved.

Free-polymer controlling morphology of α-MoO 3 nanobelts by a facile hydrothermal synthesis, their electrochemistry for hydrogen evolution reactions and optical properties

Orthorhombic molybdenum oxide (α-MoO 3) nanobelts were successfully synthesized by the 100–180 °C and 2–20 h hydrothermal reactions of (NH 4) 6Mo 7O 24·4H 2O solutions containing 15 ml 2 M acid (HNO 3, H 2SO 4 or HCl) with no surfactant and template adding. These products were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopy, and electron microscopy (EM). In the present research, the product synthesized by the 180 °C and 20 h hydrothermal reaction of the solution containing HNO 3 was α-MoO 3 nanobelts with >10 μm long and <200 nm wide. Electrochemistry for hydrogen evolution reactions (HER) and optical properties of the as-synthesized α-MoO 3 nanobelts were characterized by linear sweep voltammetry (LSV) and Tafel plot, including UV–vis and photoluminescence (PL) spectroscopy. These imply that α-MoO 3 nanobelts show satisfied performance for HER, with the 3.75 eV direct allowed band gap ( E g ) due to the charged transition of O 2p → Mo 4d, including the emission of 437 nm wavelength at room temperature.

Electroless Ni-P plating on Mg-Li alloy by two-step method

Pretreated Mg-Li alloy sheets were pre-plated in a NiCO 3·2Ni(OH) 2·4H 2O solution to form a thin Ni-P alloy film and then plating in a NiSO 4·6H 2O solution was carried out to obtain a protective coating. The surface morphology, structure and corrosion resistance of the coating were studied. The results showed that a flat, bright and compact plating layer, which was integrated into the matrix metal, was obtained. The P content of the Ni-P coating reached 13.56% (mass fraction). The hardness value of the Ni-P coating was about HV 549. The polarization curve showed that the corrosion potential of the Ni-P coating reached −0.249 V (vs SCE). A long passivation region was found on the polarization curve, and this phenomenon indicated that the coating has an excellent anti-corrosion property.

Mechanism of electro-catalytic oxidation of shikimic acid on Cu electrode based on in situ FTIRS and theoretical calculations

In this paper, in situ Fourier Transform Infrared Spectroscopy (FTIRS) is used to study the electro-catalytic oxidation mechanism of shikimic acid (SA) at a copper electrode in H 2O and D 2O solution, respectively. As the potential is applied between 0.1 V and 0.2 V vs. SCE, SA is oxidized to 3-dehydroshikimic acid (DHS). Then a significant change appeared when the potential is scanned from 0.3 V to 0.8 V, DHS is decomposed to transaconitate and formate. As the potential is over 0.9 V, formate is further oxidized to CO 2. Density functional theory (DFT) calculation of the IR spectra is in good agreement with the experimental observation. The adsorption of transaconitate through carboxyl on copper electrode is also evidenced by p- and s-polarized radiation in FTIRS.

Formation mechanism of fibrous cobalt oxalate precipitated from alkaline Co 2+–NH 3–C 2O 42−–H 2O system

The cobalt oxalate particles with fibrous morphology were obtained by precipitating CoCl 2 and mixed (NH 4) 2C 2O 4, NH 3·H 2O solutions in a double jets process. The samples were characterized by SEM, XRD, FTIR, TG/DTA and GCMS. Thermodynamic calculations and experiments revealed that the formation of Co(NH 3) n 2+ ( n = 1,2,…,6) results in species variation of cobalt oxalate precipitated in alkaline Co 2+–NH 3–C 2O 4 2−–H 2O system. It was found that there are two kinds of cobalt oxalates precipitated in Co 2+–NH 3–C 2O 4 2−–H 2O system with the change of synthetic conditions. One is β-CoC 2O 4·2H 2O with a square columnar morphology. The other is Co(NH 3) 1.5C 2O 4·2H 2O with a fibrous morphology, a species of cobalt oxalate without being recorded in newest JCPDS files. The formation mechanism of fibrous cobalt oxalate powders is that Co(NH 3) 1.5C 2O 4·2H 2O precipitates in alkaline Co 2+–NH 3–C 2O 4 2−–H 2O system.

Dehydration of ethyl acetate aqueous solution by pervaporation using PVA/PAN hollow fiber composite membrane

Using poly(vinyl alcohol) (PVA) as coating material, tartaric acid (Tac) and maleic anhydride (Mac) as cross-linking agents and the poly(acrylonitrile) (PAN) hollow fiber ultrafiltration membrane as support layer, the PVA/PAN composite membrane was prepared by dip-coating method used for pervaporation (PV) dehydration of ethyl acetate (EAc)/H 2O solution. The PVA/PAN composite membrane was characterized by FT-IR spectra and SEM. The effects of cross-linking agents on the swelling degree and PV performance of PVA/PAN membrane were investigated, respectively. The separation factor of PVA/PAN composite membrane increased while the permeation flux decreased with increasing the contents of cross-linking agents, and PVA/PAN membrane exhibited better PV performance when Tac/PVA mass ratio was 0.2. Furthermore, the PV performance of PVA/PAN composite membrane for EAc/H 2O solution was investigated with respect to the feed temperatures and feed water concentrations. For PVA/PAN composite membrane with Tac/PVA mass ratio of 0.2, its performance for 2 wt.% water of EAc solution at 40 °C was evaluated as follows: the separation factor and permeation flux were 7270 and 34.5 g m −2 h −1, respectively. In addition, PVA/PAN composite membrane was also used for PV dehydration of EAc/ethanol (EtOH)/H 2O ternary solution.

The effect of oil-droplet on bubble absorption performance in binary nanoemulsions

The objectives of this paper are to study the absorption characteristics of NH 3 bubbles in binary nanoemulsions and to quantify the effect of oil-droplet on the bubble absorption performance. C 12E 4 and Tween20 are used as the surfactants and n-decane oil is added into NH 3/H 2O solution to make the binary nanoemulsion. The initial concentration of NH 3/H 2O solution and the concentration of oil are considered as the key parameters. The absorption rates are calculated by measuring the inlet and outlet mass flow rates per a given time period. In addition, the droplet size in the binary nanoemulsion is measured by the particle size analyzer (ELS-Z, OTSUKA ELECTRONICS). It is found that the effective absorption ratio for 2.0 vol% oil and 14.3 wt% NH 3/H 2O becomes 17% higher than that for the base fluid.

Eu(III) and Tb(III) luminescent lanthanide systems derived from DTPA-bisamide and DTTA-based ligands incorporating bipyridine antenna

Four new polycarboxylate ligands H 3 L n have been synthesized by the attachment of two or one 2,2′-bipyridine subunits onto a diethylenetriamine pentacarboxylic acid (DTPA-bisamide derivatives: H 3 L 1 , H 3 L 2 ) or a diethylenetriamine tricarboxylic acid (DTTA derivatives: H 3 L 3 , H 3 L 4 ) core. The neutral Eu III and Tb III complexes of these chelates have been prepared and studied from their UV–vis and luminescence data. The main photophysical characteristics of these complexes, i.e. the absorption and luminescence spectra, the metal-centred lifetimes and the overall luminescence yields ( Φ) were measured in buffered aqueous solutions. In addition the role played by non-radiative paths (vibrational energy transfer involving coordinated water molecules, involvement of ligand-to-metal charge-transfer excited states, or metal→ligand back-transfer) was investigated. In all complexes, we found that the bidentate bipyridine chromophore is not coordinated to the lanthanide ion, allowing one (Ln L 1 , Ln L 2 ) or two (Ln L 3 , Ln L 4 ) water molecules to penetrate the first coordination sphere of the metal. Although the bipyridine chromophore behaves as remote (from the binding site) light-harvesting unit for the lanthanide ion in these systems, a sizeable sensitization of the Eu- and Tb-centred luminescence can be effective (Ln L 2 , Ln L 3 , Φ=16–19% in aerated D 2O solutions). Our photophysical investigations show that overall non-radiative deactivation is not dependant of thermally activated non-radiative channels but the efficiency of the ligand→Ln intramolecular energy transfer has to be taken into account to explain the obtained results.

The experiment research of corrosion behaviour about Ni-based alloys in simulant solution containing H 2S/CO 2

Aimed at the problem of tubing corrosion in environment that containing hydrogen sulfide (H 2S), carbon dioxide (CO 2), and chlorides (Cl −), the corrosion behaviour of two nickel based alloys (UNS 06985 and UNS 08825) in 15 wt%NaCl solution containing H 2S/CO 2 in high temperature and high pressure environment was investigated. The pitting corrosion behaviour of Ni-based alloys was studied in FeCl 3·6H 2O solution by means of polarisation curve and immersion tests. The scanning electron microscopy (SEM), energy disperse spectroscopy (EDS) was applied to analyse the microstructure and corrosion performance of the samples. The results showed that the pitting-resistant of nickel alloy UNS 06985 was superior to UNS 08825. With the rising of experimental temperature, the corrosion increased and some slight pitting attacks appeared on the surface of UNS 08825. The test temperature was the crucial factor that influenced not only the compactness and the growing rate of corrosion product scale, but also the corrosion rate of the alloys. Elemental sulfur is a strong oxidant, the presence of S0 leads to a serious localized corrosion. XRD showed that the corrosion films formed on nickel base alloys consisted of NiS, CrO 3, and the oxides of Ni and Fe. The polarisation curves showed a different corrosion behaviour of two alloys, anodic curve of UNS 06985 has a wider passivation area, and there has higher transpassive potential.

Effect of extra-framework silicon on the catalytic activity of Cuβ zeolite catalyst for synthesis of diethyl carbonate by oxidative carbonylation of ethanol

Effect of extra-framework silicon of Cuβ catalysts was investigated by oxidative carbonylation of ethanol in the gas-phase reaction. Zeolite β crystals with varying Si/Al ratio were obtained after different content aqueous NH 3·H 2O solution treatment. Cuβ catalyst with low Si/Al ratio has shown better catalytic activity for oxidative carbonylation of ethanol to diethyl carbonate (DEC). From X-ray powder diffraction (XRD), XPS, and ICP analysis, it can be concluded that the treatment of NH 3·H 2O for β zeolite facilitated selective extraction of extra-framework silicon, which produce enough room for the active center Cu +. The reaction of forming active sites for Cuβ without extra-framework silicon was studied on a molecular level using density functional theory (DFT) and transition-state theory. The reactive energy barrier of the reaction over Hβ without extra-framework silicon was lower than that with extra-framework silicon, mainly because the stereo-hindrance of SiO 2 in the support has great effect on CuCl activation. And the presence of extra-framework silicon of the support blocked the attack of Cu + to O atom. Hence, Cuβ catalyst without extra-framework silicon has better catalytic activity.

Synthesis, X-ray crystal structure and fluorescent spectra of novel pyrazolo[1,5- a]pyrazin-4(5 H)-one derivatives

A series of fluorescent compounds, containing pyrazolo[1,5- a]pyrazin-4(5 H)-one moiety, were designed and synthesized from ethyl 1-(2-oxo-2-phenylethyl)-3-phenyl-1 H-pyrazole-5-carboxylates. The structures of the compounds have been confirmed by IR, 1H NMR, HRMS and X-ray crystal diffraction. The optical properties of the compounds were investigated by UV–vis absorption and fluorescence spectroscopy. The effect of pH on the UV–vis absorption of compound 2a in methanol–H 2O solutions was studied and interpreted by theory calculation. The p K a value of compound 2a was determined by the absorption spectra.

Two copper(II) complexes with 4-benzoylpyridine ligand: Synthesis, crystal structure and luminescent properties

Two new copper(II) complexes Cu(NCS) 2(4-Bzpy) 2 ( 1) and Cu(NO 3) 2(4-Bzpy) 4 ( 2) (4-Bzpy = 4-benzoylpyridine) have been synthesized and characterized by IR, UV, elemental analysis and X-ray crystallography. Cu(II) atom has a square planar environment for 1 and an distorted octahedral environment for 2, respectively. In solid state there are C–H⋯π interactions and C–H⋯S hydrogen bonds between adjacent molecules in complex 1. The molecule of complex 2 is further connected by multiform π–π interactions, C–H⋯π interactions and C–H⋯O hydrogen bonds to form a three-dimensional supramolecular structure. The luminescent properties of the complexes 1 and 2 were both investigated in H 2O solution and in solid state at room temperature, respectively.

Electrospinning of PAN/DMF/H 2O containing TiO 2 and photocatalytic activity of their webs

Polyacrylonitrile (PAN) nanofiber webs containing titanium dioxide (TiO 2) were prepared via electrospinning. Either dimethyl formamide (DMF) or its mixture with small amount of water (3 and 5%w/w.) was employed to prepare 5%w/w.PAN/DMF or PAN/DMF/H 2O solution, respectively. Introducing non-solvent water in PAN/DMF/H 2O solution was attempted to induce phase separation, which may lead to formation of porous structure on nanofibers surface. Different amounts of TiO 2 (1 to 3 wt.%) were added into PAN/DMF/(H 2O) solutions and then electrospun into nanofiber webs. From SEM, nanofibers possessed rough surfaces and had averaged diameters in ranges of 170–430 nm., showing tendency to increase with amount of TiO 2 and water. Porous structure on fiber surfaces was not clearly observed, which was suspected to be due to insufficient amount of water employed. Less homogeneity in polymer solution due to presence of TiO 2 disfavored increasing water content higher than 5%w/w. EDS data confirmed presence of TiO 2 in electrospun webs. From photocatalysis evaluation, webs containing 2 and 3 wt.% TiO 2 showed good photocatalytic activity such that 80 percent of 10 ppm. methylene blue degraded in 24 hours. Slight increase in photocatalytic activity was observed in webs obtained from PAN/DMF/H 2O solutions.

The effect of seed layer thickness on alignment and morphology of ZnO nanorods

Thin films of ZnO of 20, 40,160 and 320 nm thickness were deposited on Si (100) substrates by rf-magnetron sputtering and then nanorods were grown on the seed layer at 95 °C for 2 h. The ZnO nanorods were synthesized in C 6H 12N 4 and Zn (NO 3) 2·6H 2O solution by a hydrothermal method and the effect of seed layer thickness on the alignment, diameter, density and growth rate of nanorods was studied. The results revealed that the alignment of nanorods depended on crystallinity, grain size and roughness frequency of the sputtered seed layer, so that, with increase of seed layer thickness, crystallinity improved. In addition the grain size increased and the roughness frequency decreased and hence alignment and diameter of nanorods increased. Finally, we present a model for the effect of seed layer thickness on the alignment and diameter of the nanorods.

Effect of surface tension gradient on gas hold-up enhancement in aqueous solutions of electrolytes

The effect of addition of electrolytes on gas hold-up of air/water system was investigated experimentally in a laboratory scale bubble column. The experiments were carried out with four electrolytes, namely, NaCl, MgSO 4·7H 2O, Na 2SO 4 and CaCl 2·2H 2O and the concentrations of the solutions were varied from 0 to 0.3 mol/l. Enhancement of gas hold-up was observed for all four electrolytes at concentrations less than 0.1 mol/l. With the increase in concentration, the gas hold-up showed two different trends; in Na 2SO 4 and CaCl 2·2H 2O solutions, gas hold-up formed a sharp peak after the enhancement and leveled off at a value somewhat higher than that in water, whereas in NaCl and MgSO 4·7H 2O solutions, gas hold-up leveled off immediately after the enhancement without forming any peak. Experiments were also conducted to measure the surface tensions of the solutions with special focus in the low concentration region. A strong relation between the gas hold-up enhancement and the change of surface tension with the addition of electrolyte was found. It was also observed that the concentration at which maximum value of C( dσ/ dC) 2 i.e. ( concentration × surface tension gradient with respect to concentration 2) is obtained corresponds to the concentration at which maximum gas hold-up enhancement occurs.

Electrodeposition of gold thin films from 1-butyl-1-methylpyrrolidinium dicyanamide Au 3+ solutions

The electrodeposition of gold from a HAuCl 4.3H 2O solution in 1-butyl-1-methyl-pyrrolidinium dicyanamide is reported in the present paper. A cyclic voltammetry study of the electrochemical behaviour of the plating solution showed that the reduction of gold occurs by a two-step process. Gold thin films were obtained by electrodeposition on nickel substrates under potentiostatic control at a constant potential of − 1 V, for temperatures from 293 to 353 K and deposition times of 1500 and 4500 s . The films prepared at 293 and 333 K consist of 9–15 nm diameter polyhedral particles aggregated in clusters 50–250 nm in diameter. The films deposited at 353 K consist of a quasi-continuous film of nanoparticles covered by nanosized dendrites. This morphology evolves towards a globular structure with increasing deposition time.

TR-ESR Investigation on Reaction of Vitamin C with Excited Triplet of 9,10-phenanthrenequinone in Reversed Micelle Solutions

Time-resolved electron spin resonance has been used to study quenching reactions between the antioxidant Vitamin C (VC) and the triplet excited states of 9,10-phenanthrenequinone (PAQ) in ethylene glycol-water (EG-H2O) homogeneous and inhomogeneous reversed micelle solutions. Reversed micelle solutions were used to be the models of physiological environment of biological cell and tissue. In PAQ/EG-H2O homogeneous solution, the excited triplet of PAQ (3PAQ*) abstracts hydrogen atom from solvent EG. In PAQ/VC/EG-H2O solution, 3PAQ* abstracts hydrogen atom not only from solvent EG but also from VC. The quenching rate constant of 3PAQ* by VC is close to the diffusion-controlled value of 1.41 × 108 L/(mol ·s). In hexadecyltrimethylammonium bromide (CTAB)/EG-H2O and aerosol OT (AOT)/EG-H2O reversed micelle solutions, 3PAQ* and VC react around the water-oil interface of the reversed micelle. Exit of 3PAQ* from the lipid phase slows down the quenching reaction. For Triton X-100 (TX-100)/EG-H2O reversed micelle solution, PAQ and VC coexist inside the hydrophilic polyethylene glycol core, and the quenching rate constant of 3PAQ* by VC is larger than those in AOT/EG-H2O and CTAB/EG-H2O reversed micelle solutions, even a little larger than that in EG-H2O homogeneous solution. The strong emissive chemically induced dynamic electron polarization of As.− resulted from the effective TM spin polarization transfer in hydrogen abstraction of 3PAQ* from VC.

Kinetics of hydrogen iodide decomposition over activated carbon catalysts in pellets

Three commercial carbons in pellets have been tested as catalysts for HI decomposition reaction in the range of temperature 240–500°C. A preliminary screening, conducted under identical conditions, permitted to correlate conversion values to carbons characterization data. The most active carbon was deeply investigated, showing no deactivation for the entire testing time (140h) and no secondary reaction with H2O (of the HI solution). Comparing the results obtained at different temperatures, contact times, feedings (pure HI and liquid HI–H2O solution) and I2 impurities, it was possible to derive a new kinetic mechanism and find out reliable values for I2 and HI adsorption heats, as well as for the activation energy of the reaction; H2O adsorption resulted greater than HI's. The mechanism proposed entails that atomic iodine, once formed on the catalyst surface, behaves in an auto-catalytic way for the HI molecules decomposition. This translates into a particular dependence of the reaction rate on HI pressure: at rather low pressure and/or high temperatures, rate grows with pressure; when pressure is high and/or temperature is low, rate may decrease with pressure.