Double-supply-frequency pressure pulsation in annular linear induction pump: Part I: Measurement and numerical analysis

This paper describes an experimental and analytical study of double-supply-frequency pressure pulsation arising in an annular linear induction pump. In a large-scale induction pump, it is known that the supply frequency should be relatively low in order to satisfy a magnetohydrodynamic stability criterion. Under such a low supply frequency, however, double-supply-frequency pressure and flow rate pulsation generated in an induction pump may be of concern. The experimental data obtained in the present work shows that the amplitude of the pressure pulsation increases with decreasing supply frequency, number of poles and/or slip. The numerical result reveals that the pressure pulsation comes from a disturbance of the electromagnetic force near the stator ends.     

Indirect electrochemical synthesis of active oxygen in dilute sulfate solutions

Anodic oxidation of dilute solutions of sodium sulfate was developed to generate oxidants into aqueous solutions with a diaphragm electrolyzer, which consisted of titanium anodes covered with mixed oxides of iridium, ruthenium and tin, a titanium cathode, and Teflon cation-exchange membrane. An electronic device was created for continuous self-purification of cathode surface from hardness salt deposits. The anodic products of electrolysis were molecular oxygen and sodium persulfate. It should be noted that sodium persulfate was the only active oxidant. The synthesized anolyte was tested for its oxidizing activity towards certain metabolites and toxicants. Disinfecting properties of anolyte were detected towards gram-positive and gram-negative bacteria. The comparison of redox potentials of commercial samples of persulfate and the synthesized anolyte showed that the redox potential value for the anolyte is much higher than for solutions with the same concentration of commercial persulfate.     

Polyoxometalate catalyzed ozonation of chemical pulps in organic solvent media

Polyoxometalate (POM) catalyzed ozonation of chemical pulps in organic solvent media was found to be particularly effective and selective environmentally benign bleaching approach providing a way for substantial increase in pulp brightness, viscosity and degree of delignification in comparison with other ozone-based bleaching techniques. A series of tested low-boiling polar aprotic and protic organic solvents showed a well-defined capacity for ozonation improvement in the presence of Keggin-type heteropolyanion [PMo₇V₅O₄₀]⁸⁻ (HPA-5). Even moderate solvent proportion of 6% (w/w) in the reaction solution caused additional gain in brightness up to 3.4% ISO with simultaneous increase in pulp viscosity up to 8.8% and lignin removal up to 18.9% after HPA-5 catalyzed ozonation (0.8% O₃; 0.5 mM HPA), as compared with the control solvent-free process. An aqueous acetone solution was found to be the preferred reaction medium in terms of pulp brightening and delignification. Under optimized conditions, the POM-catalyzed ozonation of eucalypt kraft pulp in acetone/water solution showed remarkable brightness improvement by 15.1% ISO with additional lignin removal by 39.4% and increase in intrinsic viscosity by 3% in comparison with pulp bleached in water media.     

On a Crack in Viscoelastic Isotropic Media Opened by a Rigid Growing Wedge

Wedging of an isotropic linear viscoelastic space with crack by a rigid semi-infinite indentor is studied. The wedge is assumed to have growing with time thickness. An analysis is done in the framework of generalised Dugdale model and COD criterion using Volterra's principle. The results for safe wedge growth law as well as for the crack growth are obtained.     

Alkynes Carbonylation Reactions in Solutions of Palladium Complexes as a New Class of Oscillatory Processes

This article dedicated to study of few oscillating reactions in homogeneous systems. The experimental data and preliminary mechanism are reported. The authors affirm they find new type of oscillating processes—the reactions of carbonylation.     

Towards the integration of dark and photo fermentative waste treatment. 1. Hydrogen photoproduction by purple bacterium Rhodobacter capsulatus using potential products of starch fermentation

In this study, the H₂-photoproduction capacity of Rhodobacter capsulatus B10 was measured as a function of variations in the nature and concentration of volatile fatty acids (VFAs) and other products of dark fermentation. When an equimolar mixture of VFAs was provided, C4 substrates (butyrate and isobutyrate) were not consumed until the C2–C3 substrates (acetate, propionate, and lactate) became unavailable, but in order for the cells to produce H₂ at high rates they could not be exposed to severe growth substrate depletion. Among other possible fermentation products, the highest inhibition was observed by the addition of butanol (50% inhibition at 50 mM). The influence of high concentrations of VFAs, phosphate (used to stabilize the pH during dark fermentation) and some heavy metals (known inhibitors of methanogenesis) was also shown. Based on the results, the conditions of fermentation can be manipulated to avoid the inhibition of subsequent H₂ photoproduction by photosynthetic bacteria.     

Conversion of brown coal in supercritical water without and with addition of oxygen at continuous supply of coal-water slurry

A study of conversion of organic matter of brown coal in supercritical water (SCW) at 30 MPa, 400−760 °C and continuous supply of coal-water slurry (CWS) into a tubular reactor is presented. It was found that 48−63% (depending on the SCW temperature) of coal organic matter (COM) is ejected from CWS coal particles as liquid and gaseous products when they move through the reactor. We termed this stage of SCW conversion as dynamic conversion (DC) of coal. It turns out that the particles which underwent the DC stage did not aggregate in the reactor during static conversion (SC) within a coal layer due to continuous pumping through this layer. The experimental data on the composition of DC and SC products, degree of coal conversion, and the data on the degree of combustion of carbon in the presence of oxygen are given.     

SOLVENT EXTRACTION OF PALLADIUM FROM CHLORIDE SOLUTIONS BY ALKYLAMMONIUM DI(2-ETHYLHEXYL)DITHIOPHOSPHATES

ABSTRACT

The extraction of palladium (II) from chloride solutions (over a wide region of aqueous acidity) by di(2-ethylhexyl)dithiophosphates of tetraoctylammonium, tri-n-octylammonium and di-n-octylammonium in toluene at the constant chloride concentration has been studied. A synergistic effect was shown to be observed in these systems and it is explained by the formation of unusual complexes with mixed ligands. It has been established the palladium complexes, such as (R₃NH)[PdCl₂A], (R₃NH)[PdCl₂A] and (R₂NH₂)[PdCl₂A], involving both alkylammonium cation and dialkyldithiophosphate anion are extracted under conditions of the loaded organic phase using distribution methods depending on a composition of aqueous and organic phase. At the excess of R₃NHA or R₂NH·HA, PdA₂ is extracted into the organic phase. Table 8 reports the results obtained and indicates the domains of existence of the various species of palladium (II) extracted into the organic phase in the binary ex-tractant systems in comparison with the initial systems     

Efficiency of naphthalene biodegradation by Pseudomonas putida G7 in soil

The efficiency of naphthalene degradation by Pseudomonas putida G7 in soil was assessed using a mathematical model. The number of microorganisms and the concentration of naphthalene in soil samples were monitored. The feasibility of a spectrofluorometric method for naphthalene assay in soil samples was compared with high pressure liquid chromatography. A proposed mathematical model described the growth of the naphthalene‐degrading strains and the consumption of substrates (naphthalene, naphthalene degradation intermediates and soil organic substances) in soil. To describe the growth kinetics of microorganisms having high affinity to substrates with low solubility, two differential equations with substrate exponent 2/3 were proposed. These equations were used to describe utilization of soil organic matter. The model parameters characterize the growth rates for different substrates and respective yield coefficients, specific bacterial death and adaptation rates, and also the rates of PAHs degradation and evaporation. These characteristics can be used in choosing the bacterial strains for biopreparations and efficient clean‐up biotechnology of polluted soils. Copyright © 2004 Society of Chemical Industry