Possible mechanism of metal ion extraction from aqueous solutions by fibrous polypropylene

Peculiarities of the extraction of metal ions from aqueous solutions by fibrous polypropylene have been investigated. It has been found that metal ion adsorption proceeds owing to the existence of a gas-liquid-hydrophobic polymer boundary line. The process mechanism has been discussed.     

Effect of methanol dilution on H-ZSM-5 zeolite deactivation in the process of light olefin formation

Conversion of methanol in the presence of H₂O, O₂, H₂, CO, CO₂ and He was studied at 733 K on H-ZSM-5 zeolite. The effect of diluent on the selectivity to light olefins and resistance to coking of H-ZSM-5 were observed. Among the diluents studied only water exerts a promoting effect on prolonged activity of the catalyst. Some explanations of the deactivation process are given.

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H₂O, O₂, H₂, CO, CO₂ He H-ZSM-5 733K. H-ZSM-5. . .

     

2-Diphenylphosphinoyloxybenzaldehyde 4-Nitrophenyl-, 4-Phenyl-1-phthalazinyl-, and Aroylhydrazones and Thiosemicarbazone

Condensation of aryl- and aroylhydrazines and thiosemicarbazide with 2-diphenylphosphinoyloxybenzaldehyde results in formation of the corresponding hydrazones and thiosemicarbazone. The products give rise to conformational equilibrium between rotational and Z,E isomers, which is strongly displaced toward the E,E',Z' isomer and is determined by the nature of substituent in the hydrazine fragment.     

The lipids of microalgae II. Lipids of the dry biomass ofMonochrysis lutheri

Institute of the Chemistry of Plant Substances, Uzbekistan Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 899–900, November–December, 1993.     

Effect of hydrothermal treatment on catalytic properties of superhigh-silica zeolites

The effect of hydrothermal treatment of decationized superhigh-silica zeolite on the mechanism of n-hexane conversion has been studied. It has been established that thermosteam modification sharply decreases the cracking activity and increases the selectivity to aromatization reactions. Zeolite acidity markedly decreases, but its crystal structure does not become amorphous.

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THE QUANTUM EFFICIENCY FOR THE INTERPHOTOCONVERSION OF THE BLUE and PINK FORMS OF PURPLE MEMBRANE

When the cations bound to purple membrane are removed it turns blue, and when this blue membrane is irradiated its color changes to pink. Irradiation of pink membrane leads to the reformation of blue membrane. We have determined that the quantum efficiency for the formation of pink membrane from deionized blue membrane is 1.6 ± 0.6 ± 10 ⁴ at 0^oC, pH 5.0. We also found that the quantum efficiency for the back photoconversion, i.e. the formation of blue membrane from pink membrane, is 8.8 ± 1.6 ± 10^-3 at 0^oC, 55 times greater than that of the forward photoconversion reaction. The extinction coefficients of the pink membrane and blue membrane were determined to be 44 500 ± 670 cm^-1 M^-1 at 491 nm and 54 760 ± 830 cm^-1 M ^-1 at 603 nm, respectively, assuming light-adapted purple membrane is 63 000 cm^-1 M ^-1 at 568 nm. The quantum efficiency for forming pink membrane from blue membrane is much lower than that for forming the photointermediate of the blue membrane's photocycle. Their relationship is similar to that of light-adaptation and photocycle of the dark-adapted purple membrane.     

OVERVIEW ON SURFACE MICROSTRUCTURING BY PHOTODESORPTION ETCHING OF CHLORINATED SILICON

Developing a mechanistic interpretation of complex dynamical chemical systems such as halogen photoetching requires correlated microscopic data on the kinetics, dynamics, surface composition and microstructure of prototypical and real surfaces. This overview is concerned especially with two important variables which significantly influence the microetching mechanisms and structures; (I) the role of electronic point defects induced by substitutional doping in producing site-specific reactions and, (II) the quantum mechanical enhancement of chemical reaction induced by uv-radiation at low fluences and temperatures.

From uv-photoetching and photodesorption studies of heavily doped Si(100) and Si(111) with chlorine beams at low laser fluences, the mechanisms of photostimulated desorption is analyzed based primarily on the kinetics of chemisorption and surface layer microanalysis obtained from core-level photoemission. These results are coupled with time-of-flight dynamical measurements on the energetics of the photodesorption process to provide a more unified understanding of anisotropic photon-stimulated microetching.

Substantial alterations of the etching mechanisms occur when selective surface molecular processes are driven quantum mechanically by low level photon radiation rather than thermally. This is clearly reflected in the dynamical mechanisms for photodesorption which become strongly site- and atomic process-selective illustrated by the energetics of the processes. Creation and transport of charged carriers, especially at high doping levels by photoionization coupled with field-induced charge transport, introduces new reaction channels into the surface chemistry leading to resultant changes in the microstructure on an atomic scale. The results from the kinetics, velocity dynamics and film composition measurements are combined in terms of the dependency of chlorine adsorption on doping at high carrier levels and low laser fluences, to provide an improved interpretation of the anisotropic microetching in terms of field-promoted electron-hole activation.