Ethylenediamine Cobalt Research Articles

Kinetics for the simultaneous removal of NO and SO 2 with cobalt ethylenediamine solution

NO can be removed from exhaust gas streams by using a basic solution of cobalt ethylenediamine (H 2NCH 2CH 2NH 2). The cobalt ethylenediamine acts as a homogeneous catalyst to oxidize NO into soluble nitrogen dioxide and realize the oxidation and absorption of nitric oxide simultaneously. The dissolved oxygen in equilibrium with the residual oxygen in the exhaust gas stream acts as the oxidant. SO 2 can also be removed by the Co(en) 3 3+ (en stands for ethylenediamine) solution. A double-stirred reactor with a plane gas–liquid interface that was planar to close approximation was used to measure the absorption rates of NO into the Co(en) 3 3+ solutions. The experiments demonstrate that the gas–liquid reaction becomes gas film controlling as the cobalt ethylenediamine concentration exceeds 0.03 mol l −1 when there is 1200 ppm SO 2 in the gas phase. The NO absorption rate decreases as SO 2 concentration increases. Oxygen in the gas phase accelerates the NO absorption rate into the cobalt ethylenediamine solution. The optimal temperature for nitric oxide absorption is 50 °C. The NO absorption rate increases as the pH of the Co(en) 3 3+ solutions rises.

Synthesis, characterization and catalytic activity of halo-methyl-bis(salicylaldehyde)ethylenediamine cobalt(II) complexes

The synthesis, characterization and catalytic activity of a series of tetra-halo-dimethyl salen and di-halo-tetramethyl-salen ligands are reported in this paper: α,α′-dimethyl-Salen (dMeSalen) ( L 1 ); 3,3′,5,5′-tetrachloro-α,α′-dimethyl-Salen, (tCldMeSalen) ( L 2 ); 3,3′-dibromo-5,5′-dichloro-α,α′-dimethyl-Salen, (dCldBrdMeSalen) ( L 3 ); 3,3′,5,5′-tetrabromo-α,α′-dimethyl-Salen, (tBrdMeSalen) ( L 4 ); 3,3′,5,5′-tetraiodo-α,α′-dimethyl-salen, (tIdMeSalen) ( L 5 ); 3,3′-dichloro-5,5′,α,α′-tetramethyl-Salen (dCltMeSalen) ( L 6 ); 3,3′-dibromo-5,5′,α,α′-tetramethyl-Salen (dBrtMeSalen) ( L 7 ); and 3,3′-diiodo-5,5′,α,α′-tetramethyl-Salen (dItMeSalen) ( L 8 ) (Salen = bis(salicylaldehyde)ethylenediamine). Upon reaction with Co(II) ions, these ligands form complexes with square planar geometry that have been characterized by elemental analysis, cyclic voltammetry, UV–Vis, IR and EPR spectroscopies. In the presence of pyridine the obtained Co(II) complexes were found able to bind reversibly O 2, which was shown by EPR spectroscopy and cyclic voltammetry. They were also found able to catalyze the oxidation of 2,6-di- tert-butylphenol (DtBuP) ( 9) with formation of 2,6-di- tert-butyl-1,4-benzoquinone (DtBuQ) ( 10) and 2,6,2′,6′-tetra- tert-butyl-1,1′-diphenobenzoquinone (TtBuDQ) ( 11). These properties are first influenced by the coordination of pyridine in axial position of the Co(II) ion that causes an increase of the electronic density on the cobalt ion and as a consequence a decrease in the E 1/2 value and an increase of the reducing power of the Co(II) complex. It is noteworthy that, under those conditions the complexes also show a remarkable quasi-reversible behaviour. Second, complex properties are also influenced by the substituents (methyl and halogen) grafted on the aromatic ring and on the azomethynic groups. The donating methyl substituent on the azomethynic groups causes a decrease in the E 1/2 value, whereas the halogen substituents on the aromatic rings have two effects: a mesomeric donating effect that tends to lower the redox potential of the complex, and a steric effect that tends to decrease the conjugation of the ligand and then to increase the redox potential of the Co(II) complex. In pyridine, the steric effect predominates, which causes both an increase of the redox potential and a decrease of the selectivity of the oxidation of phenol 9. As a result of all these effects, it then appears that the best catalysts to realize the selective oxidation of 2,6-di- tert-butyl-phenol ( 9) by O 2 are the Co complexes of ligands bearing CH 3 donating substituents, Co(dMeSalen) 1 (2CH 3 substituents), and Co-di-halo-tetra-methyl-salen complexes 6, 7 and 8 (4CH 3 substituents), in the presence of pyridine.

A cobalt(III) complex containing coordinated and non-coordinated carboxylates: trans -[(nitro)bis(ethylenediamine)(3,5-dinitrobenzoato)- cobalt(III)][3,5-dinitrobenzoate

Trans-[(nitro)bis(ethylenediamine)(3,5-dinitrobenzoato)cobalt(III)][3,5-dinitrobenzoate] ([trans- Co(en)2NO2(C7H3N2O6)]C7H3N2O6) has been obtained by mixing aqueous solutions of trans-dinitrobis(ethylenediamine)cobalt(III)nitrate and sodium 3,5-dinitrobenzoate in 1 : 1 molar ratio. Elemental analyses and spectroscopic techniques (IR, electronic, 1H and 13C NMR) were used to characterize the complex salt. An X-ray structure determination revealed the salt to consist of discrete [trans-Co(en)2NO2(C7H3N2O6)]+ and (C7H3N2O6)− ions. The salt is triclinic, space group , with a = 10.3790(1), b = 14.4421(2), c = 14.4421(2) Å, α = 88.0100(4), β = 79.1820(4), γ = 84.8690(6)°, Z = 6, V = 3789.50(9) Å3. The crystal lattice is stabilized by electrostatic forces and N–H ··· O hydrogen bonds between cations and anions resulting in a unique salt containing coordinated and non-coordinated 3,5-dinitrobenzoate groups.

Absorption of NO in Aqueous Solution of Co(II)-en: Determination of the Equilibrium Constant

In a wet scrubbing process, the addition of ethylenediamine cobalt(II) (Co(II)-en) to enhance the solubility of NO in aqueous solution may provide a good environmental control technology (coordination catalysis reactions absorption) for removal of NO, after the use of a SO 2 scavenging process, that requires little capital when combined with a highly developed industrial wet desulfurization processes. Under anoxic conditions according to amount of time-dependent absorbed NO under different NO partial pressure, the mole ratio of reacted NO and Co(II)-en in the coordination reaction nNO + [Co(en) 3 ] 2+ ⇔ [Co(en) 3 (NO) n ] 2+ was determined to be 1:1, that is n = 1. From this, the formula of the formed nitrosyl metal complex is derived to be [Co(en) 3 (NO)] 2+ . For the development of this scrubbing technological process, knowledge of thermodynamic equilibrium data of the reaction NO + [Co(en) 3 ] 2+ ⇔ [Co(en) 3 (NO)] 2+ over a range of temperatures is of prime importance. In the temperature range from (30 to 90) °C, the equilibrium constant has been determined, and the experimental data fit the following equation well: Kp = (3.3153 ± 0.1160) x 10 -4 exp(4428.5 ± 96.2/T)/bar -1 where the reaction enthalpy is ∇H 0 = -(36.821 ± 0.800) kJ·mol -1 .

Nitric oxide absorption into cobalt ethylenediamine solution

NO pollutant causes acid rain and urban smog. The removal of NO from exhausted gas streams is necessary to meet stringent effluent discharge limits. NO can be removed from exhausted gas streams by putting soluble cobalt salts and ethylenediamine (H 2NCH 2CH 2NH 2) into basic solutions. The Co(en) 3 3+ (en stands for ethylenediamine) ion produced by ethylenediamine binding cobalt acts as a homogeneous catalyst to oxidize NO into soluble NO 2 and realize the oxidation and absorption of nitric oxide in the same reactor. The dissolved oxygen in equilibrium with the residual oxygen in the exhausted gas stream acts as the oxidant. The experiments manifest that this process is superior to the methods using Fe(II)–ethylenediaminetetraacetate (EDTA) solution and H 2O 2 solution as absorbents in removing NO from the exhausted gas stream. NO removal efficiency decreases with the increase of the gas flow rate. NO removal efficiency increases with the Co(en) 3 3+ concentration. pH of the solution affects the NO removal efficiencies obviously. Under anaerobic condition, the NO removal efficiency decreases with pH when pH is over 7.73. Under aerobic condition, there is an optimal pH for NO absorption into the Co(en) 3 3+ concentration. More than 90% of NO in the feed gas can be removed by the Co(en) 3 3+ solution.

DNA binding and cleavage properties of certain ethylenediamine cobalt(III) complexes of modified 1,10-phenanthrolines

Two complexes of the type [Co(en) 2IP] 3+ (IP = imidazo[4,5-f][1,10]-phenanthroline) and [Co(en) 2PIP] 3+ (PIP = 2-phenylimidazo[4,5-f][1,10]-phenanthroline) have been synthesized and characterized by UV–VIS, IR and 1H NMR spectral methods. Absorption spectroscopy, emission spectroscopy, viscosity measurements and DNA melting techniques have been used to investigate the binding of these two complexes with calf thymus DNA and photocleavage studies have been used to investigate the binding of these complexes with plasmid DNA. The spectroscopic studies together with viscosity measurements and DNA melting studies support that complexes 1 and 2 bind to CT DNA(=calf thymus DNA) by an intercalation mode via IP or PIP into the base pairs of DNA. Complex 2 binds more avidly to CT DNA than 1, which is consistent with the extended planar ring π system of PIP. Noticeably, the two complexes have been found to be efficient photosensitisers for strand scissions in plasmid DNA.

Studies on antimicrobial activity of cobalt(III) ethylenediamine complexes

A series of cobalt(III) mixed ligand complexes of type [Co(en)2L]+3, where L is bipyridine, 1,10-phenanthroline, imidazole, methylimidazole, ethyleimidazole, dimethylimidazole, urea, thiourea, acetamide, thioacetamide, semicarbazide, thiosemicarbazide, or pyrazole, have been isolated and characterized. The structural elucidation of these complexes has been explored by using absorption, infrared, and 1H NMR nuclear magnetic resonance spectral methods. The infrared spectral data of all these complexes exhibit a band at 1450/cm and 1560-1590/cm, which correspond to C=C and C=N, a band at 575/cm for Co-N (en), and a band at 480/cm for Co-L (ligand). All these complexes were found to be potent antimicrobial agents. The antibacterial activity was studied in detail in terms of zone inhibition, minimum bactericidal, and time period of lethal action. Among all, complexes bipyridine, 1,10-phenanthroline, dimethylimidazole, and pyrazole, possess the highest antibacterial activity. Antifungal activity was done by disc-diffusion assay and 50% inhibitory concentrations that possess high antifungal activity.

The use of cobalt ethylenediamine tetraacetic acid as a soluble marker in the determination of rumen outflow rate in sheep

Rumen outflow rate in sheep was studied using cobalt ethylenediamine tetraacetic acid as soluble rumen marker in three rumen fistulated sheep of an average body weight of 9.6±0.07kg. Single dose time sequence spot sampling technique was adopted at various time intervals of 2, 4, 6, 8, & 24 h. The ruminal concentrations of cobalt ethylenediamine tetraacetic acid after each post-dosing spot sampling time was determined by a graphical comparison of spectrophotometric absorbance of known concentrations of cobalt ethylenediamine tetraacetic acid and the absorbance of equal volume of ruminal fluid collected from each sheep at given time intervals post-dosing with marker. Depletion of marker with time from the rumen reflected the liquid turnover in the rumen. The ruminal volume of marker distribution was estimated as 1.5499±0.0198L. Using the exponential equation for determining the fractional turnover rate, the average fractional turnover rate was 0.09624±0.0017/h or 9.624%. The rumen half- life of the marker was 7.204±0.12h. The average outflow rate was 0.149±0.002L/h. The data obtained will help in regulating feeding time of intensively reared sheep towards achieving high voluntary intake of dry matter and effective rumen degradability of ruminant feed fractions, which are influenced by rumen outflow rate.Keywords: cobalt ethylenediamine tetraacetic acid, rumen, outflow rate, sheepNigerian Veterinary Journal Vol. 26(1) 2005: 18-24

Crystal structure of tris(ethylenediamine)cobalt(III) (aqua)hexachloromercurate(II) chloride [Co(En)3]2[Hg2(H2O)Cl6]Cl4

The compound [Co(En)3]2[Hg2(H2O)Cl6]Cl4 (I, En is ethylenediamine) has been synthesized and studied by X-ray diffraction. The crystals of I (a = 21.8745(14) A, b = 10.6008(6) A, c=15.4465(12) A, space group Pna21) consist of tris(ethylenediamine)cobalt(III) complexes (the unit cell contains two [Co(En)3]3+ cations of opposite chirality). [Hg2(H2O)Cl6]2− anions, and isolated chloride ions. The complex anion consists of the tetrahedral [HgCl4]2− group (Hg-Cl, 2.44–2.56 A) and the hydrated molecule [Hg(H2O)Cl2] (Hg-Cl, 2.301 and 2.308 A; Hg-O, 2.788 A) combined by weak Hg-Cl interactions (2.915 and 3.220 A).

Synthesis and spectroscopic characterization of trans-[Co(en)2(NO2)2]X (X = dodecyl sulfate, picrate, diclofenac or saccharinate) and the single-crystal X-ray structure of the saccharinate salt, trans-[Co(en)2(NO2)2](C7H4NSO3)·H2O

trans-[Co(en)2(NO2)2]X complexes, where X = C12H25SO4 (1), C6H2N3O7 (2), C14H10Cl2NO2 (3) and C7H4NSO3 (4), have been synthesized by slowly mixing aqueous solutions of trans-dinitrobis(ethylenediamine)cobalt(III) nitrate and sodium dodecyl sulfate, picrate, diclofenac and saccharinate, respectively, at a 1 : 1 mol ratio. Good crystals of trans-dinitrobis (ethylenediamine)cobalt(III) saccharinate monohydrate, [Co(en)2(NO2)2](C7H4NSO3)·H2O, were obtained. The salt is orthorhombic, space group P21212, with a = 21.553(2), b = 8.503(1), c = 10.238(1) Å, Z = 4, V = 1876.3(3) Å3, R 1 = 0.0286 and wR 2 = 0.0727. A structure determination revealed an ionic structure consisting of discrete [Co(en)2(NO2)2]+ cations and [C7H4SO3N]– anions.

Kinetics of Gas−Liquid Reaction between NO and Co(en)33+

NO can be removed from exhaust gas streams by using a basic solution of cobalt ethylenediamine (en = H 2 NCH 2 CH 2 NH 2 ). The cobalt ethylenediamine acts as a homogeneous catalyst to oxidize NO into soluble nitric dioxide and realize the oxidation and absorption of nitric oxide simultaneously. The dissolved oxygen in equilibrium with the residual oxygen in the exhaust gas stream acts as the oxidant. A stirred vessel with a plane gas-liquid interface was used to measure the absorption rates of NO into Co(en) 3 3+ solutions under anaerobic conditions and under aerobic conditions. The experiments demonstrate that the nitric oxide absorption reaction can be regarded as instantaneous when nitric oxide concentration levels are at ppm levels. The gas-liquid reaction becomes gas film controlling as the cobalt ethylenediamine concentration exceeds 0.02 M. Oxygen in the gas phase is favorable for the absorption of nitric oxide. The optimal temperature for nitric oxide absorption is 60 °C under anaerobic conditions and 50 °C with 5.2% oxygen present in the gas phase. The kinetics equation of NO absorption into Co(en) 3 3+ solutions in the presence of oxygen can be written as N NO = [2K NO,G (p NO + γ C Co(en)3 3+ ,L )H O2 (k 2 D O2,L ) 1/2 p O2 ]/pk -1 + 2H O2 (k 2 D O2,L ) 1/2 p O2 ].

Removal of Sulfur Dioxide and Nitric Oxide Using Cobalt Ethylenediamine Solution

NO can be removed from exhaust gas streams by placing soluble cobalt salts and ethylenediamine (H2NCH2CH2NH2) into basic solutions. The cobalt ethylenediamine acts as a homogeneous catalyst to oxidize NO into soluble nitric dioxide and realize the oxidation and absorption of nitric oxide simultaneously. The dissolved oxygen in equilibrium with the residual oxygen in the exhaust gas stream acts as the oxidant. Lime desulfurization scrubbers can be retrofitted for combined removal of SO2 and NOx from the flue gas by adding cobalt ethylenediamine to lime slurries. The experimental results in a bench-scale scrubber indicate that such a catalyst system can maintain a high NO removal for a long time. NO removal rate increases with a feed oxygen concentration up to 7.8% or higher. According to the experiments performed, a minimum of 0.02 M of CaO is necessary to ensure a high NO removal rate when 1500 ppm of SO2 is present in the feed. The NO removal rate remains the same with an excess of CaO, due to solubility limitations. The optimal temperature is about 50 °C. More than 90% of NO and nearly 100% of SO2 in the feed gas are removed by the Co(en)33+ in a CaO slurry scrubbing solution.

Kinetics and mechanism of substitution of chloride ion in trans-[Co(en)2Cl2]+ by organic bases in dimethyl acetamide solution

The kinetics of substitution of chloride ion in trans-dichlorobis(ethylenediamine) cobalt(III) cation by five organic bases (diethylamine, triethylamine, benzylamine, t-butylamine and n-propylamine) in dimethylacetamide (DMA) at ionic strength of 0.80 M NaClO4 is reported. The activation parameters for the second-order path lie on a good isokinetic line. The linear plots of kobsvs. [B], the large negative values of ΔS2‡ and the span of k2 values signify an associative mechanism.

Polymer‐immobilized N,N′‐bis(acetylacetone)ethylenediamine cobalt(II) Schiff base complex and its catalytic activity in comparison with that of its homogenized analogue

AbstractFor the preparation of a heterogenized N,N′‐bis(acetylacetone)ethylenediamine cobalt(II) Schiff base complex, first crosslinked polymer beads were prepared by the suspension copolymerization of styrene (48.97 mmol, 5.1 g), allyl chloride (48.97 mmol, 3.746 g), and divinyl benzene (DVB; 1.75 mmol, 0.228 g) in the presence of azobisisobutyronitrile (0.9 × 10−3 mmol, 0.15 g) as an initiator at 23 ± 0.1°C under an inert atmosphere. The copolymerization of styrene, allyl chloride in the presence of gelatin (0.75 g), bentonite (2.0 g), and boric acid (2.5 g) produced beads of different crosslinked densities corresponding to the concentration of DVB in the reaction mixture. The amount of allyl chloride in the prepared beads varied from 5.40 to 7.40 mmol g−1 of beads with the amount of DVB varying from 2.0 to 0.8 mmol in the reaction mixture. A quadridentate Schiff base (acen) was prepared with ethylenediamine (5.0 mmol, 0.3 g) and acetylacetone (10.0 mmol, 1.0 g), and it was used to obtain a homogenized and heterogenized Co(II)(acen)2 complex. The extent and arrangement of the Schiff base (acen) in the crosslinked beads depended on the availability of DVB in the reaction mixture. The amount of DVB in the reaction mixture influenced the extent of cobalt(II) ion loading, the degree of swelling, the porosity, and the pore size in the prepared beads. The beads (type IV) prepared with 1.75 mmol (0.228 g) of DVB in the reaction mixture showed a degree of swelling of 9.65% and efficiencies of loading and complexation for cobalt(II) ions of 49.4 and 85%, respectively, in comparison with beads obtained at other concentrations of DVB in the reaction mixture. The structure of free and polymer‐supported Co(II)(acen)2 complexes was verified with IR, UV, and magnetic measurements, which suggested a square planar geometry for the complexes under both conditions. The catalytic activities of the homogenized and heterogenized Co(II)(acen)2 complexes were compared by the evaluation of the rate constant (k) for the decomposition of hydrogen peroxide. The heterogenized Co(II)(acen)2 complex showed a high catalytic activity for the decomposition of hydrogen peroxide (k = 2.02 × 10−4 s−1) in comparison with the homogenized Co(II)(acen)2 complex (k = 4.32 × 10−6 s−1). The energy of activation for the decomposition of hydrogen peroxide with the heterogenized Co(II)(acen)2 complex was low (38.52 kJ mol−1) in comparison with that for the homogenized complex (73.44 kJ mol−1). In both cases, the rate of decomposition of hydrogen peroxide was directly proportional to the concentration of hydrogen peroxide and cobalt(II) ions. On the basis of experimental observations, a rate expression for the decomposition of hydrogen peroxide was derived. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1398–1411, 2003

Solubilities and Gibbs transfer energies of thiolato, sulfenato, sulfinato and tris(ethylenediamine)cobalt(III) complexes, as well as of perchlorate,from acetonitrile into its mixtures with water

Information on the solvation of thiolato complex cations [Co(en)2(SCH2COO)]+ [Co(en)2(SCH2CH(COO)NH2)]+, [Co(en)2(SCH2CH2NH2)]2+, sulfenato complexes [Co(en)2(SOCH2COO)]+ [Co(en)2{SOCH2CH(COO)NH2}]+, [Co(en)2(SOCH2CH2NH2)]2+, the sulfinato [Co(en)2{SO2CH2CH(COO)NH2}]+, [Co(en)2(SO2CH2CH2NH2)]2+ as well as of [Co(en)3]3+ has been obtained from solubility measurements in MeCN–H2O mixtures at 298.2 K. The single-ion Gibbs energies of transfer of the CoIII complexes were derived from the solubilities of picrate and perchlorate salts for the full range of MeCN–H2O mixtures. Single-ion Gibbs energies of transfer for the perchlorate ion are given. The effects of the solvent mixtures were interpreted in the framework of chemical bond formation between the ions and the individual solvent molecules.

Activity and Osmotic Coefficients from the Emf of Liquid Membrane Cells. X. Tris(Ethylenediamine) Cobalt(III) Nitrate, Perchlorate, and Chloride

Activity coefficients of [Co(en)3](NO3)3 and [Co(en)3](ClO4)3, to be compared with [Co(en)3]Cl3 and the corresponding lanthanum salts previously studied, are determined. [Co(en)3]Cl3 data are revised. Ion interaction strengths vary in the same order found for La3+, i.e., as if nitrate and perchlorate ions were of smaller and larger size, respectively, than chloride ions; however, the differences are much smaller than in lanthanum salts. Tris(ethylenediamine)cobalt III and lanthanum nitrate, chloride, and perchlorate—like the corresponding hexacyanoferrate(III) and hexacyanocobaltate(III) salts, but contrary to sulfate salts—behave as if [Co(en)3]3+ were smaller in size than La3+. In the dilute regions, [Co(en)3](NO3)3 displays negative deviations from the limiting slope, a kind of behavior typical for 2:2, 2:3, 3:2, and 3:3 electrolytes, but unnoticed earlier for 3:1 or 1:3 electrolytes. Pitzer's equation parameters able to provide accurate activity and osmotic coefficients for [Co(en)3](NO3)3, [Co(en)3](ClO4)3, and, revised, [Co(en)3]Cl3 are reported.

Dielectric Properties of Ethyethlenediamine Cobalt Nitrate (ECN) Single Crystals

Dielectric properties of [Co(H 2 N(CH 2 ) 2 NH 2 ) 3 ](NO 3 ) 3 (ethylenediamine cobalt nitrate, ECN) single crystals have been investigated. Dielectric constants measured at 10 kHz exhibited anomalies around 110 K and 140 K in addition to a tiny anomaly at 250 K. Dielectric dispersion measurements in the frequency range from 100 Hz to 1 MHz have been performed between room temperature and 20 K to investigate the mechanism of the dielectric anomalies. Two Debye-type relaxation modes with rather long relaxation times were found. The temperature dependence of the dielectric strengths, relaxation times, indices for distribution of relaxation time was determined.

Chiral recognition in association between antimony potassium tartrate and bis(L-alaninate)ethylenediamine cobalt(III) complexes using electrospray ionization mass spectrometry

The chiral recognition of metal complexes by a quick and sensitive mass spectrometric analysis was investigated. The principle is introduction of an external chiral standard compound and detection of the differential association with two optical isomers. Using electrospray ionization mass spectrometry we detected weak intermolecular association between the external chiral anion bis(μ-L-, D-tartrato)-diantimonate(III), [Sb 2(L-, D-tart) 2] 2− and isomeric bis(L-alaninate) ethylenediamine cobalt(III) complex ions, [Co(L-ala) 2(en)] + in acetonitrile/water solution. The difference in the association with optical isomers of the Co complex was measured. The results were interpreted based on a model of intermolecular interaction involving hydrogen bonding. The prospects of the mass spectrometry method for chiral recognition using the external chiral negative ion [Sb 2(L-, D-tart) 2] 2− was discussed.

Effect of Nonsolvent/Oxygen Carrier Additives on Gas Separation Performance of Polycarbonate Membranes

N,N′-Dimethylformamide (DMF) and N,N′-dialicylidene ethylene diamine cobalt(II) (CoSalen) were added into the casting solution to improve both the gas permeability and oxygen/nitrogen selectivity of polycarbonate (PC) membranes. PC membranes formed by a simple dry method are known to have high oxygen/nitrogen selectivity but low gas permeability. A nonsolvent, DMF, was added into the casting solution to improve the membrane permeability, and an oxygen carrier, CoSalen, was added to improve the oxygen/nitrogen selectivity. The addition of DMF increased the membrane permeability but reduced the oxygen/nitrogen selectivity. On the contrary, the addition of CoSalen raised the selectivity but suppressed the permeability. To make a membrane of selectivity near the value of native PC membrane but with a higher gas permeation rate by adjusting the DMF and CoSalen contents in the casting solution, the highest oxygen permeation flux of CoSalen complexed porous PC membranes was 0.61 GPU(10−6 × cm3/cm2.s.cmHg) at an O2/N2 selectivity of 4.7 at 35°C. This membrane was obtained when 19 vol% of DMF and 4.8 wt% of CoSalen were added into the PC casting solution. This specific membrane, after a long period of storage, 400 days, had a higher oxygen flux (0.88 GPU) which was obtained without any loss in selectivity. At a lower temperature, 5°C, an even higher oxygen selectivity of 7.9 was obtained.

Solvent effects on the kinetics of aquation of κ‐chloro(diethylenetriamine) (ethylenediamine)cobalt(III) ion in mixed aqueous solvents

Solvent effects on the kinetics of aquation of κ‐chloro(diethylenetriamine) (ethylenediamine)cobalt(III) ion in mixed aqueous solvents