bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adsorption of copper (II) ions from aqueous solution by five silica samples
Authors: Bye Gerald C. , McEvoy Michael , Malati Mounir A. 
Published: July 2010

AbstractSamples of BDH precipitated silica, Degussa TK900 (non‐porous) and Crosfield xerogels [A (mesoporous), B (mesoporous) and C (microporous)] were characterised by chemical analysis, by Coulter particle‐size analysis, by electron microscopy and by their BET surface area. The point of zero charge, determined by potentiometric acid/alkali titration, was at pH 2.8–2.9 for all samples. The surface charge density for the non‐porous sample was lower than that for the porous samples. The results of the initial rate of exchange of the silicas with tritiated water suggested an exchange with the physically held water, which is lost at 393 K. The adsorption isotherms of Cu (II), determined by atomic absorption spectrophotometry at pH 6 and 323 K, followed the Langmuir equation. The limiting adsorption capacity decreased in the order: precipitated silica > B > A > C > TK900. This order could not be correlated with the BET nitrogen surface area or the pore volumes of the samples. However, the order was the same as the Na+ content of the silicas. Desorption runs established that adsorption was not reversible, in fact desorption was significant at equilibrium concentrations approaching zero. An apparent endothermic heat of adsorption of Cu (II) on precipitated silica, calculated from the data of the Langmuir isotherms at different temperatures, was 23 kJ mol−1. The increase in the adsorption of Cu (II) as the pH increased may be ascribed to the adsorption of hydrolysed species. From the Grahame equation, the estimated free energy of specific adsorption of Cu (II) on precipitated silica near the point of zero charge was‐13 kJ mol−1.
Bacillus sphaericus V‐penicillin acylase. II. Isolation and characterisation
Authors: Carlsen Flemming , Emborg Claus 
Published: July 2010

AbstractBacillus sphaericus (strain NCTC 10338) produces an intracellular V‐penicillin acylase which has been isolated and partially purified after lysozyme treatment. The acylase hydrolyses V‐penicillin and V‐cephalosporin but not G‐penicillin and ampicillin. Optimal activity occurred at 40–60°C and pH 6.8. The system showed some characteristics of an SH‐enzyme and was inhibited by phenoxyacetic acid (non‐competitive, Ki =30 mM) and 6‐aminopenicillanic acid (competitive, Ki =9 mM). The Km for V‐penicillin was 140 mM.
Some studies of silica‐supported Pd‐Au catalysts and their behaviour in the hydrogenation of 1‐octyne in the liquid phase
Authors: Brown J. M. , Caga I. T. , Welsh C. K. , Wilson S. J. , Winterbottom J. M. 
Published: July 2010

AbstractA number of silica‐supported palladium‐gold (Pd‐Au) catalysts have been prepared by simultaneous impregnation covering the range 0–84 atomic % gold in palladium, the total metal loading on the silica being about 2% (w/w). In addition, a smaller number of unsupported Pd‐Au catalysts covering the same composition range was prepared by Adams oxide methods and these are compared with the supported catalysts. The catalysts were examined, as appropriate, by temperature‐programmed reduction (TPR), carbon monoxide chemisorption for metal surface area measurement, X‐ray diffraction and Auger electron spectroscopy. The hydrogen‐reduced catalysts were used for 1‐octyne hydrogenation in the range 30–70°C, at 1 atm. total pressure, with propan‐1‐ol as reaction solvent. Certain catalysts were also air‐treated after reduction, after which their activities and surface areas were determined. For the supported Pd‐Au alloys, TPR and catalyst‐activity studies indicated that alloying between gold and palladium occurred, possibly over the whole composition range, but more certainly up to 50–60 atomic % gold in palladium. No evidence for alloying was found in the case of the unsupported Adam Pd‐Au catalysts on the basis of X‐ray, Auger spectroscopic and activity measurements. Air‐treatment of selected supported catalysts resulted in enhanced activity for 1‐octene hydrogenation and increased metal surface areas. This is attributed to removal of surface carbon and an activity maximum was observed for an air/catalyst ratio of 0.2–0.3 cm3of air/mg of catalyst. Beyond the optimum air/catalyst ratio, activity and surface area decreased again, probably due to oxygen or water chemisorption on palladium. 1‐Octyne hydrogenation rate was unaffected by such treatment and its ability to chemisorb strongly causes inhibition of activity, whether or not carbon is present.
Ion‐exchange behaviour of hydrous zirconia in mixed solvents: Thermodynamics of anion exchange in methanolic solutions
Authors: Misak N. Z. , Ghoneimy H. F. 
Published: July 2010

AbstractAddition of 30 and 60% (w/w) methanol decreases ΔG0 and increases ΔH0 and ΔS0 of the exchange of Cl− for NO3− in hydrous zirconia and thus the increase of selectivity constant is due to the entropy term. In the case of exchange of Br− for NO3−, a decrease of the selectivity constant occurs at 30% (w/w) methanol also due to the entropy changes, whereas at 60% (w/w) methanol, the selectivity constant continues to decrease as a result of both ΔHo and ΔSo terms which became higher than in the aqueous solution. Selectivity reversal occurs in the NO3−/Cl− exchange at 60% (w/w) methanol, whereas in the NO3−/Br− exchange, it occurs already at 30% (w/w) methanol. Calculations for Cl−/Br− exchange with the use of transfer thermo‐dynamic data revealed that ion‐solvent interactions in the liquid phase are the sole factor governing the variation of ΔG0 on addition of methanol, and thus ΔG0 (or selectivity constant) in the mixed media could be largely calculated from the value in the aqueous medium when these interactions are accounted for by introducing transfer free energy (or medium effect) terms. However, changes in the solid‐phase interactions, leading to decreases in ΔH0 and ΔS0, do occur on addition of methanol but these decreases largely cancel each other.
High pressure synthesis of diphenylamine from aniline and phenol
Authors: Radhakrishnan Mala , Das Birendra N. , Nandi Dilip K. 
Published: July 2010

AbstractThe synthesis of diphenylamine from aniline and phenol has been carried out in the presence of a phosphoric acid catalyst. Very high pressure has no beneficial effect on the synthesis of diphenylamine. Under optimum conditions (558 K 0.552 × 106 N m−2; residence period 2 h; aniline to phenol mol ratio, 1:3 and aniline to catalyst mol ratio, 1:0.3232), the conversion of aniline to diphenylamine was 72.57%.
Separation of some radio‐elements from low‐level liquid wastes using hemimorphite mineral
Authors: Hafez Mohamed B. , Abdel‐Rassoul A. A. 
Published: July 2010

AbstractThe use of hemimorphite mineral for possible decontamination of low‐level radioactive liquid wastes has been investigated. Fixation and subsequent elution systems for some radionuclides from both aqueous and phosphate media using hemimorphite were studied. Changes in pH and ageing of radioactive tracers in used media were the principal factors affecting such systems. Sorption rather than ion‐exchange is likely to occur.
Optimised aerobic and thermophilic treatment of municipal sewage sludges and night soils in a continuous operation
Authors: H. Carlson Carl‐Göran 
Published: July 2010

AbstractIn this investigation aerobic and thermophilic (57°C) biodegradation of raw and partly digested municipal sludges and night soils is optimised at a commercial waste treatment centre. The feed is monitored to 5–7% dry solids and BOD7 concentration of 30–50 g kg−1. BOD7 removal exceeds 85%. Effluents are accepted for land infiltration.
The role of pigmentation in the growth and survival of the methanol‐utilising bacterium, Pseudomonas extorquern
Authors: Merabtine Hamida , Scott Christopher D. B. , Harrison David E. F. , Oliver Stephen G. 
Published: July 2010

AbstractThe role of pigmentation in the growth and survival of Pseudomonas extorquens (NCIB 9399) has been examined in both the pink wild‐type strain and a yellow mutant (T358) derived from it. The effect of inhibitors of carotenoid biosynthesis has also been assessed. The yellow mutant was found to compete out the wild‐type when the two organisms were grown together in methanol‐limited continuous culture. The methanol dehydrogenase of the mutant was found to have a lower Km and higher Vmax than that of the wild‐type. The response of mutant and wild‐type cells to the growth inhibitory effects of methanol was similar. Moreover, incubation with chemical inhibitors of carotenoid biosynthesis did not alter the growth rate of the wild‐type over a range of methanol concentrations. The pink pigment did, however, have a photoprotective effect and stationary phase wild‐type cells were more resistant to the killing effects of ultraviolet light than the yellow mutant cells.
Adsorption from aqueous solution by δ‐manganese dioxide I. Adsorption of the alkaline‐earth cations
Authors: Gray Malcolm J. , Malati Mounir A. 
Published: July 2010

AbstractThe adsorption isotherms of M2+ ions (M = Mg, Ca, Sr or Ba) were determined at pH 7.0 and at different temperatures. The adsorbent, δ‐MnO2, was converted to the K+ form prior to adsorption and about 1.5 mol K+ ions were released per mol of M2+ ions adsorbed. The adsorption capacity at a given temperature increased in the series: Mg2+ < Ca2+ ≦ Sr2+ < Ba2+. This was explained by an ion exchange mechanism between hydrated ions: K+ ions in the outer Helmholtz layer and M2+ ions in the bulk of the solution. The radii of the hydrated ions decreased in the series: Mg2+ > Ca2+ > Sr2+ > Ba2+. The adsorption of M2+ ions at pH values below the point of zero charge (pH 3.3) was significant for Mg2+ ions only. Although adsorption was not strictly reversible, the results fitted the Langmuir isotherm and ‘apparent heats of adsorption’, Q, were calculated. The endothermic heats (Q = 20,18, 11 and 5 kJ mol−1 for Mg2+, Ca2+, Sr2+ and Ba2+ adsorption respectively) indicated positive entropy contributions which are expected for the adsorption mechanism suggested. The decrease in Q down the alkaline‐earth group was correlated to the entropy effects and to the hydration numbers of the cations.
Electroreduction of phenyl cyanide and benzyl cyanide on nickel cathode
Authors: Krishnan Venkatasubramanian , Muthukumaran Arunachalam , Ragupathy Kanagasabhapathy , Udupa Venkata Krishna 
Published: July 2010

AbstractAn electrochemical method for preparation of primary amines from organic cyanides using nickel black deposited over graphite substrate as cathode has been studied. It has been observed that it is possible to reduce benzyl cyanide both in ethanolic sulphuric acid and in aqueous ethanolic ammonium sulphate media. But with phenyl cyanide, the reduction is efficient only in ethanolic sulphuric acid medium. Both in laboratory and 75 A scale experiments 62–66% yield has been obtained at a current efficiency of 36–44% for benzylamine. Similarly a yield ranging from 60–80% with a current efficiency of 36–52% has been obtained for β‐phenylethylamine both in laboratory scale and also in large scale experiments. Results of operation of a 500 A cell for the preparation of β‐phenylethylamine are also presented.
Continuous ion exchange with magnetic shell resins dealkalisation part V—Process development
Authors: Priestley Anthony J. 
Published: July 2010

AbstractA search has been made for a continuous ion exchange adsorber design that would be suitable for flow rates in the range 4500–45 000 m3day−1. By the use of fundamental kinetic data, various types of adsorber were designed from first principles. Economic analysis of the results of this design study suggested the use of a simple pipeline, in which the ion exchange resin is carried along in the turbulent water flow. Experimental work confirmed the predicted advantages of the pipeline as an adsorption vessel.
Growth yield of Rhodopseudomonas spheroides in light‐anaerobic and dark‐aerobic cultures
Authors: Aiba Shuichi , Koizumi Jun‐Ichi , Nishizawa Yoshinori 
Published: July 2010

AbstractAn experimental fact that the quantum yield, defined by moles of thiocyanate ion released per unit light energy absorbed in a photochemical reaction of Reinecke's salt solution, remains almost unchanged in a visible wavelength range from 400 to 700 nm was applied to the measurement of light energy absorbed by Rhodopseudomonas spheroides in a continuous culture vessel in situ. This technique of light energy assessment was deemed to be significant in the sense that not only the light energy that was transmitted but also that that was scattered in three dimensions could be assessed. Values of growth yield, Ykj, for light‐anaerobic and dark‐aerobic cultivations of this microorganism were 0.012 g cell per kJ and 0.028 g cell per kJ, respectively. These values sound reasonable in the light of relevant data on Ykj published by other workers on various chemo‐organotrophic and/or photolithotrophic microbes.
Bismuth molybdates: Preparation and catalysis
Authors: Batist Philip A. 
Published: July 2010

AbstractOnly one bismuth molybdate, Bi2MoO6 or the Koechlinite phase, has proved to be an active catalyst for olefin oxidation. The activities of the other compounds, Bi2Mo2O9 and Bi2Mo3O12 are merely due to coverage of these compounds by Bi2MoO6. This coverage is also due to the fact that the Koechlinite phase is quickly obtained from the reactants, whereas the other compounds are obtained more slowly. Koechlinite is active and stable, but sensitive to decomposition if not treated properly. A procedure is described for obtaining pure and active Koechlinite crystals. Such a procedure is important, because the natural mineral Koechlinite is always contaminated with quartz. Surface models are given to explain the selectivity, the non‐selective reaction, oxygen diffusion and deactivation of differently prepared bismuth molybdate catalysts.
Reclamation of waste plastics and rubber: Recovery of materials and energy
Authors: Poller Robert C. 
Published: July 2010

AbstractThe world‐wide production of waste plastics and rubber is increasing with much of it appearing in domestic refuse. This waste should be regarded as a minor but valuable resource of energy and materials but it is largely dumped instead of being reclaimed. Those methods of reclamation which lead to breakdown of the polymeric structure are considered here. The principal methods of recycling are combustion with energy recovery, pyrolysis and depolymerisation. Each of these methods is surveyed in detail. It is concluded that social and economic measures are needed to stimulate greater use of existing technology which, in turn, would allow the development of more sophisticated technology.
The effect of preparation variables on the dispersion of supported platinum catalysts
Authors: Palmer M. B. , Vannice M. A. 
Published: July 2010

AbstractThe effects of several preparation variables on the dispersion of supported platinum catalysts were examined in this study. Supported catalysts were prepared using two different platinum salts, four high surface area support materials, and two aqueous deposition techniques. The catalysts were characterised by hydrogen chemisorption, oxygen chemisorption, and the hydrogen titration reaction. In addition, X‐ray diffraction measurements were conducted on all catalysts. Results from this study show that one of the platinum salts, chloroplatinic acid, always gave an equally or more highly dispersed catalyst than the other salt, tetraammine platinum (II) nitrate. The incipient wetness preparation technique produced equal or better dispersions than did the excess water method, with the possible exception of the silica‐alumina support. The highest dispersions were attained with alumina, and the lowest with carbon. In some samples, a lack of good agreement existed between X‐ray diffraction and chemisorption measurements of crystallite size which indicated broad or bimodal particle size distributions. However, these X‐ray data were qualitatively helpful in understanding the unusual chemisorption behaviour of Pt/C catalysts, one of which had a dispersion higher than any previous reported Pt/C catalyst prepared by aqueous impregnation techniques. Experiments were also conducted which showed that either a 1 h or a 12 h treatment in hydrogen at 723 K was sufficient to reduce the platinum salt, and 1 h or 12 h evacuations at 698 K gave similar results. Finally, it was found that approximately one‐half of the hydrogen monolayer on supported Pt could be removed by evacuating for 1 h at 300 K.
Kinetics of citric acid fermentation from n‐paraffins by yeasts
Authors: Moresi Mauro , Cimarelli Delfo , Gasparrini Giuliana , Liuzzo Giuseppe , Marinelli Roberto 
Published: July 2010

AbstractIn this work, yeast of the genus Candida was screened by means of shaken‐flask and jar fermentations. Two strains, Candida lipolytica Cooper and ATCC 8661, were selected. Their citric acid productivity was 0.79 and 0.67 g g−1 of n‐paraffins consumed, respectively, and their citric: total citric and isocitric acid ratios ranged from 0.82 to 0.93, respectively. The experimental results (cell growth and total citric and isocitric acid formation) were described by using an unstructured kinetic model which has been proposed previously (standard error was less than 10%). Moreover, each independent kinetic parameter was correlated with the aeration rate of the culture medium by means of empirical regressions. Aeration of the culture medium showed a large influence on the product yield. For instance, the strain C. lipolytica Cooper exhibited the highest productivity among the examined strains, associated with the largest air consumption.
The application of the principles of reaction engineering to electrochemical cell design
Authors: Fleischmann Martin , Jansson Robert E. W. 
Published: July 2010

AbstractIt is shown that detailed descriptions of complex electrochemical reactors may be obtained by using electrochemical analogues of the dye marker technique. Most cells show some degree of segregation and the extent of the stagnant phase as well as the residence time distribution, degree of dispersion etc. can be correlated with the hydrodynamic conditions. The performance of electrochemical reactors is shown to be strongly dependent on the contacting patterns. It is therefore important to develop methods for predicting the distribution of reaction in space in order to predict the overall performance. It is shown that approximate design methods can be applied which combine information on the local reaction rates with information on the distribution of potential; this method of modelling is compared to that used for non‐isothermal endothermic reactions in conventional reactors.
Evaluation of activity, selectivity and stability of catalysts for naphtha reforming
Authors: Sad Mario R. , Fígoli Nora S. , Beltramini Jorge N. , Jablonski Estanislao L. , Lazzaroni Ricardo A. , Parera José M. 
Published: July 2010

AbstractA method to evaluate naphtha‐reforming catalysts has been developed and the equipment and its operation is described here in detail. The octane number computed by chromatographic analysis is similar to the one derived using the motor method and is proportional to the total aromatic concentration. The aromatic concentration is a quick and easy method to evaluate catalyst activity. The liquid yield and selectivity were also measured chromatographically. The efficiencies of commercial and prepared catalysts were compared by plotting octane number vs liquid yield. The catalysts were Pt/Al3O3‐Cl and the process variables were similar to those used in industry. The feed was n‐heptane or C6‐C8 naphtha. Accelerated deactivation tests at lower pressure and hydrogen : hydrocarbon ratios were performed to study stability in shorter times.
The inhibition of the cathodic reduction of hypochlorite by films deposited at the cathode surface
Authors: Kuhn Anselm T. , Hamzah Harun , Collins Gilbert C. S. 
Published: July 2010

AbstractFilms, either organic or inorganic in nature, can form at electrode surfaces by naturally occurring processes or can be deliberately induced to form there. The behaviour of a deliberately formed Ca(OH)2 film on the rate of cathodic hypochlorite reduction in an undivided brine electrolysis cell is examined. The results can be modelled in terms of electrode obscuration and the conditions for film formation and dissolution are also treated. It is shown that the latter is a self‐limiting process.
Desiccant efficiency in solvent drying. Applications of cationic exchange resins
Authors: Burfield David R. , Smithers Roger H. 
Published: July 2010

AbstractThis paper describes the evaluation of activated cation exchange resins as desiccants for solvent drying. Using a previously described radiotracer technique the effect of parameters such as activation temperature, desiccant loading and cation type have been investigated. Comparison with earlier evaluations of molecular sieves are made. Cation exchange resins are found to be moderately efficient and rapid desiccants. Typical equilibrium mositure contents at 5% (w/v) desiccant loadings are dioxane (600 mg dm−3), dichloromethane (10 mg dm−3) and toluene (1 mg dm−3).
Thermal decomposition of zinc zirconyl oxalate pentahydrate
Authors: Reddy V. Butchi , Mohan Rao C. Rama , Mehrotra P. Narain 
Published: July 2010

AbstractThermal decomposition of zinc zirconyl oxalate (ZZO) has been investigated employing thermogravimetric, differential thermal analysis and differential thermogravimetric techniques and chemical analysis. The decomposition proceeds through three steps. The first step is the dehydration of the zinc zirconyl oxalate pentahydrate in the temperature range 303–473 K. The second stage is the decomposition of the oxalate giving an intermediate residue containing both oxalate and carbonate between 473–613 K. The third and final stage is the decomposition of the intermediate between 613–833 K to give zinc zirconate. The infrared spectral and X‐ray data confirm the formation of ZnZrO3.
The preparation of thiophenes. II. From C5‐C7‐molecules and carbon disulphide
Authors: Azizian Farid , Pizey James S. 
Published: July 2010

AbstractSubstituted thiophenes have been obtained in high yields by passing C5‐C7‐molecules and carbon disulphide (CS2) over a promoted chromium‐aluminium oxide catalyst (Girdler G41)1 in the vapour phase at 500°C. Both the scope and mechanism of these reactions have been studied using an alkane and a number of alcohols and ketones, and the reaction products have been identified. The reaction of pentan‐2‐ol with 13C‐carbon disulphide (13CS2) has been carried out to study the incorporation of the carbon atom of the CS2 into the thiophene ring.
Hydrogenation of benzene to cyclohexene on a ruthenium catalyst: Influence of some reaction parameters
Authors: Odenbrand C. U. Ingemar , Lundin Sten T. 
Published: July 2010

AbstractThe formation of cyclohexene in the hydrogenation of benzene on a ruthenium catalyst has been studied in a slurry reactor. The reaction was performed in an alkaline aqueous phase in a stirred autoclave of stainless steel. The influence of reaction parameters, e.g. hydrogen pressure, alkali concentration, amount of catalyst and temperature was determined. The influence of poisoning of the catalyst by corrosion products is also discussed.
The formation of anthracene derivatives and substituted diphenylmethanes fromo‐bromobenzyl bromide
Authors: Barnes Ian , Robinson J. Gordon , Marr George 
Published: July 2010

Abstracto‐Bromobenzyl bromide was converted to 1‐(1‐chloro‐1‐alkyl/aryl) methyldiphenylmethanes which were then treated with aluminium chloride under anhydrous conditions when mixtures of anthracene derivatives and substituted diphenylmethanes were obtained. The size of the alkyl (or aryl) group in the chloro‐methanes influenced the relative yields of the anthracene derivatives to diphenylmethanes.