摘要:

AbstractThe polarography characteristic of uranyl ion in chromotropic acid solution was investigated systematically over the pH range 2.0 to 10.0 with ligand concentrations varying from 0.010 M to 0.200 M. At pH 5.5, the one‐electron reversible reduction waves were obtained. The temperature coefficient of the half‐wave potential was obtained to be −0.32 mV per degree and the mean value of id/h1/2is 0.340 ± 0.003. The electrode reaction is UO2(HA)24−+ c = UO2(HA)2−+ HA3−Where pH 5.5, an irreversible and diffusion‐controlled wave was obtained. The diffusion coefficients and kinetic parameters of complex species were determined by deducing instantan

ISSN:0009-4536    

DOI:10.1002/jccs.199000058

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractSolvent extraction of uranium by a chloroform solution of α‐benzoin oxime was studied and the formation of uranium‐α‐benzoin oxime complex described. The uranium‐α‐benzoin oxime complex has two maximum absorbance at 350 nm and 427 nm. A constant absorbance was obtained for 1 × 10−3M uranium when the concentration of α‐benzoin oxime was higher than 1.2 × 10−2M. Ions of Ag+, Fe3+, V5+, Cu2+, and W6+were found to have interference.A solution containing 0.1–10 mg uranium at pH 1.6–6.8 was extracted with 1 × 10−3M −2 × 10−3M α‐benzoin oxime solution in chloroform. With single extraction, the maximum amount of uranium passing into organic layer was at least 98%. Under this condition the presence of diverse ions except V5+does not significantly

ISSN:0009-4536    

DOI:10.1002/jccs.199000059

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractExtractions of uranium from the acidic media, HCl and MNO3at different concentrations, by the tertiary amines, trilaurylamine, triisooctyllamine and trioctylamine were systematically investigated. In experiments,232U was used as the tracer and aliquots of both phases after extractions were taken, ashed at 500°C, placed onto stainless steel planchets, and measured by a surface‐barrier Si(Li) detector connected to an alpha spectrometer. One unique condition found useful for complete separation of uranium was that of the radioactive uranium present in 8 M HCl being extracted with 10% trilaurylamine in xylene. In that case, greater than 95% of the uranium could be extracted into the organic solution, whereas all of the radionuclides of a series of its decayed products,228h,224Ra,220Rn,216Po and212Bi remained completely in the aqueous solution. The same procedure could also be used for the separation of uranium from a mixture with its activated nuclides. Plutonium‐239 and Am were used as the tracers representing the activated nuclides of uranium. It was found that241Am was absolutely not extracted, but that239Pu could be extracted with ≥95% efficiency from the medium of 8 M HCl into 10% trilaurylamine in xylene. However,239Pu could be easily stripped using the solution mixture of 8 M HCl and 0.05 M NH4I and excluded from the organic so

ISSN:0009-4536    

DOI:10.1002/jccs.199000060

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractA new series of polynuclear iron complexes with polydiimine ligand have been prepared from the Schiff‐base condensation of pyridine‐2, 6‐dialdehyde or 2, 6‐diacetylpyridine with aliphatic diamines. The structures of the complexes are represented by [−N = CR‐Py‐CR = N‐(CH2)n‐]2FeSO4·xH2O; where R = H, CH3; n = 4−10, × = 5∼8. Mössbauer spectra and magnetic measurements show several complexes have unu

ISSN:0009-4536    

DOI:10.1002/jccs.199000061

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractA series of Co(II), Ni(II) and Cu(II) complexes of the type [M(PC)]2H2O and [M2(PC)]4H2O, where PC is phthaleincomplexone (metalphthalein), are synthesized. It is attempted to throw some light on (heir stoichiometry, structure and stability. The formation of 1:1 and 2:1 (M:L) complexes is confirmed by their elemental microanalysis. The compounds are characterized by IR, electronic absorption spectra, X‐band ESR spectra, magnetic moments and TGA measurements. The conditional stability constants are also determine

ISSN:0009-4536    

DOI:10.1002/jccs.199000062

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractThe proton paramagnetic shifts of low spin N,N′‐ethylenebis(salicylideniminato)cobalt(II) and its derivatives were studied to understand the effect of substituents at the azomethine carbon on the electronic structure of the Schiff‐base cobalt complexes. Analysis of the1H paramagnetic shifts of H and CH3bonded to the azomethine carbon reveals that spin delocalization throughainteraction is responsible for the contact contribution to the paramagnetic shift. When the phenyl group is bonded to the azomethine carbon, the plane of the phenyl group is perpendicular to the plane of the complex and the phenyl group makes a negligible contact contribution to the paramagnetic

ISSN:0009-4536    

DOI:10.1002/jccs.199000063

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractMagnetite (FC3O4), a partially reduced iron oxide, has long been considered as inactive in the oxidative dehydrogenation of butene. By studying a clean Fe3O4powder, we found that Fe3O4, similar to other spinel ferrites, is not only active, but also more active and selective than α‐Fe2O3. The active site densities and the desorption temperatures of oxidation products on Fe3O4were also measured. Fe3O4is, however, unstable under flow reaction conditions. Even if the bulk of the oxide is stabilized in the form of Fe3O4at high temperatures and low O2/C4ratios, its surface is gradually oxidized to a form close to α‐Fe2O3, resulting in a decrease in both the activity and selectivity. The restructuring of the FC3O4surface is temperature dependent. At 300°C, the high selectivity and activity of a low‐surface‐area Fe3O4can be long preserved even if the bulk is oxidized

ISSN:0009-4536    

DOI:10.1002/jccs.199000064

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractThe A2Π ‐ X2Σ+electronic transition of MgH has been studied by the laser excitation spectroscopy. Some new transitions have been observed for the first time. Rotational parameters of the X and A state have been derived and compared with other experimental val

ISSN:0009-4536    

DOI:10.1002/jccs.199000065

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractKinetics of hydrolysis of some bifunctional Schiff bases, bis(x‐benzylidenes)‐o‐phenylenediamine, have been investigated in aqueous media containing 0.1 mole fraction of ethanol under base and acid conditions. Under base conditions the rate determining step is the hydroxide ion attack on the protonated substrate while under weak acid conditions the attack of water rather than hydroxide ion on the protonated substrate becomes the predominant reaction pathway. The bifunctional Schiff base molecular structure‐base or acid hydrolysis reactivity relationship has been examined and discussed. Effect of medium (water content and nature of organic solvents) has been investigated and it is deduced that specific solute‐solvent interactions, namely the proton‐solvent, play a vital role on such hydrolys

ISSN:0009-4536    

DOI:10.1002/jccs.199000066

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractThe chemisorptive properties of the nickel borides have been studied with temperature programmed desorption of H2and CO. The TPD chromatograms of H2show two major peaks at 150°C and 300°C for the P‐1 and P‐2W nickel borides and a major peak at 150°C for the DBNi and CrP‐1 nickel borides. Not all hydrogen molecules are dissociatively adsorbed on surface nickel, some hydrogens diffuse and are absorbed into the matrix of the nickel borides. Except the Cr‐promoted P‐1(P‐2W), the nickel borides do not exhibit the obvious chemisorptive capacity for CO. The Cr‐promoted nickel borides, on the other hand, not only have the obvious uptake capacity for CO but also have the good activity for

ISSN:0009-4536    

DOI:10.1002/jccs.199000067

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY