bluuebunny/crossref_metadata_2025_split huggingface dataset:
Examination and standardisation of amine titration in surface acidity measurements of silicas, aluminas and synthetic zeolites
Authors: Unger Klaus K. , Kittelmann Udo R. , Kreis Wilfried K. 
Published: July 2010

AbstractThe amine titration method using Hammett and arylmethanol indicators has been examined on selected samples of porous silica, active alumina and synthetic zeolites. On the basis of the successive approximation technique the evaluation of surface acid strength distribution has been standardised. A new method has been developed to assess the total acidity without employing indicators. The distinction between Bronsted and Lewis acidity through measuring the Ho and HR acidity distribution function on aluminas and zeolites is shown to be erroneous. The acidity is strongly affected by the size of amine and by the density of surface acid centres—as demonstrated on a series of silicas and on synthetic zeolites. The size dependence can be utilised to detect the acidity of distinct pore size ranges within a given porous solid. Under certain conditions the acidity measurements can be correlated with those obtained from other techniques such as heterogeneous exchange and infrared spectroscopy.
Coalescence phenomena in liquid‐liquid systems
Authors: Austin D. G. , Jeffreys G. V. 
Published: July 2010

AbstractThe factors affecting phase separation of liquid dispersion are discussed in order to identify the parameters controlling the coalescence processes occurring in primary and secondary dispersions. Models for the estimation of wedge length and band thickness in gravity settlers are reviewed, and the trends in future studies in the design and analysis of this type of equipment introduced. The phase separation of dispersions in packed beds is also considered, and the effects of the properties of the packing and the system on the coalescence processes occurring in the packing analysed. The importance of the system properties, packing voidage and the exit drop mechanism on the design of a packing for a phase separation operation are emphasised. Some recent results explaining the increased coalescence rate at the junction between a high energy and low energy surface are presented. In addition, some recent work in these laboratories on the separation of secondary dispersions are also presented.
Synthesis of 5‐hydroxymethyl‐2‐furancarboxaldehyde catalysed by cationic exchange resins. Part 3. Kinetic approach of the D‐fructose dehydration
Authors: Mercadier Daniel , Rigal Luc , Gaset Antoine , Gorrichon Jean‐Pierre 
Published: July 2010

AbstractThe best conditions for the production of 5‐hydroxymethyl‐2‐furancarboxaldehyde (HMF) in an ion exchange resin‐water‐solvent triphasic system have been determined using static operating conditions.
The growth of Aspergillus terreus and the production of itaconic acid in batch and continuous cultures. The influence of pH
Authors: Rychtera Mojmir , Wase D. A. John 
Published: July 2010

AbstractAspergillus terreus (NRRL 1960) was cultivated in batch and in continuous singlestage culture. The influence of pH on the growth of the organism, on the formation of itaconic acid and on the kinetics of fermentation was studied under phosphate limitation, both at controlled pH values and also when the pH was allowed to decrease in a natural way. In the pH range 1.7–3.5, the ratio of undissociated :half‐dissociated acid varied from 190:1 to 1.5:1. The amount of completely dissociated acid may be regarded as negligible. In batch systems operated without pH control, an initial pH of 3.1 proved to be the most effective. Product formation under such conditions started at a point where the exponential growth phase commenced and was described by a zero‐order equation. The maximum itaconic acid production rate was shifted behind maximum growth rate. The continuous single‐stage system was first order with respect to product formation. At pH > 3.1, a number of aberrant and pellet forms of the mould occurred, resulting in decreased acid production.
Cohesion energy densities and solubility parameters for the n‐alkanes expressed as a new homomorph equation
Authors: Wingefors Stig , Liljenzin Jan‐Olov 
Published: July 2010

AbstractA new correlation formula for the calculation of the cohesive energy density for n‐alkanes and the corresponding homomorphs for polar solvents has been developed. Constants of the Antoine equation and literature values of heat of vaporisation at the boiling point and at 25°C were used. For the C2‐C16 n‐alkanes the new correlation equation describes the cohesion energy density as a function of molal volume and reduced temperature within the accuracy of experimental data. In the range of reduced temperatures 0.4 < Tr < 0.7 and molal volumes 50 < V <300 cm3 the maximum deviation for this fit is less than ± 0.05 J1/2 cm−3/2. In the region of Tr and V for polar homomorphs to the n‐alkanes at 25°C the deviations are typically less than half this value.
Mesophase from electrode‐binder coal‐tar pitch: An appraisal of structural techniques
Authors: Drake John A. G. , Jones Derry W. , Mason Clifford R. 
Published: July 2010

AbstractAn electrode‐binder coal‐tar pitch containing mesophase and resulting from combined mild thermal treatment under nitrogen and hot filtration (to remove ash, etc.) has been examined by solvent analysis and magnetic resonance (high‐resolution 1H‐nuclear‐magnetic and electron‐spin resonance) spectroscopy, X‐ray diffraction and polarised light microscopy. At ambient temperature, residues and filtrates with higher mesophase contents tend to exhibit higher concentrations of unpaired electrons and higher stacks in crystalline regions. Room‐temperature 100 MHz 1H‐n.m.r. spectra of solvent extracts of the treated pitch fractions confirm the predominance of aromatic over aliphatic hydrogen in all samples; heat‐treated samples have lower content of hydrogen α to the rings but greater amounts of methylene and methyl hydrogen more remote from the rings than before the heat treatment.
Adsorption of surfactants on rocks: Microcalorimetric approach applied to tertiary oil recovery
Authors: Rouquerol Jean , Partyka Stanislaw 
Published: July 2010

AbstractResults obtained for the adsorption of surfactants (non‐ionic and ionic) on a ground sand (4.2 m2 g−1) and on a kaolin (19.4 m2 g−1) are described. The very small enthalpy of displacement of water by the surfactant molecules (5–17 mJ m−2 of adsorbing surface) and the slow structuring or rearrangement of adsorbed molecules (over several hours) would be extremely difficult to detect by techniques other than microcalorimetry.
Catalysis over bimetallic zeolites: Influence of copper on the catalytic behaviour of nickel in sodium and hydrogen Y zeolites
Authors: Coughlan Brendan , Carroll William M. , Abohalguma Ahmed 
Published: July 2010

AbstractThe catalytic activity of a range of bimetallic nickel/copper zeolite catalysts prepared from NaY and NH4Y as starting materials has been investigated; the reactions chosen were alkylation of toluene with methanol and the hydrogenation of benzene. The samples prepared from NH4Y did not reduce benzene although they contained metallic nickel; this is attributed to nickel migration and agglomeration. All the catalysts were active in alkylation and there is evidence that a Cu:Ni ratio of 3:2 favours the formation of intrazeolitic clusters and confers increased acidity on the catalysts.
Adsorption of metal cations on wool carbonising waste. Part 1. Adsorption isotherms
Authors: Farag Karim , Perineau Francis , Gaset Antoine , Molinier Jacques 
Published: July 2010

AbstractThe adsorption of various metal ions (Hg2+, Ag+, Ni2+, Cr3+, Al3+, Zn2+ and Pb2+) on wool carbonising waste has been investigated to assess its possible use as an adsorbent in water pollution control. Isotherms show that few metal ions (Hg2+, Ag+ and Ni2+) are adsorbed satisfactorily by this material. Moreover, the adsorption capacity of the plant material within the carbonising waste is higher than that of the keratin fraction. Equations fitting the experimental data can be used for the design of processing units.
Adsorption of ionic solutes on acidic lignin wastes
Authors: Perineau Francis , Gaset Antoine 
Published: July 2010

AbstractThe adsorption of surfactants and dyes on two kinds of agricultural wastes made up of acidic lignins has been investigated. One of the wastes displayed a strong affinity towards anionic solutes, whereas the other one was more efficient towards cationic solutes. These materials adsorb the organic solutes extensively. They may find use as adsorbents for the purification of industrial effluents.
Design models for adsorption systems in wastewater treatment
Authors: McKay Gordon 
Published: July 2010

AbstractThe application of mathematical models to the design of adsorption systems as a method of purifying wastewaters is considered. The design of batch, fixed‐bed, pulsed‐bed, moving‐bed and fluidised‐bed systems for effluent treatment is discussed. A brief review of the wide range of industrial effluents and adsorbents that may be utilised in such systems is considered. Reactivation procedures are presented and the principles of minimising design costs by optimising design are given.
Treatment of ammonium fluoride solutions in a semicontinuous fixed bed process
Authors: Ekdunge Per , Simonsson Daniel 
Published: July 2010

AbstractA new process for the removal of fluoride from effluents containing ammonium fluoride is described. The defluoridation is based upon the reaction of the NH4F solution with coarse calcite particles. The special technical importance of this reaction is that the limestone grains are almost completely converted to calcium fluoride without losing their shape and size. A sludge‐free process is thus possible, and the CaF2 produced can be sold as a substitute for fluorspar. A semicontinuous fixed bed of limestone particles can reduce the fluoride content by about 95–98% in a single pass. After the recovery of CO2 and NH3 by distillation, the fluoride concentration can be reduced further to 10–20 parts/106 by acidification of the solution and repeated treatments in two secondary limestone columns.
Surface interactions of carbon dioxide and pyridine with LaCrO3 perovskite‐type oxide
Authors: Fierro José Luis G. , Tejuca Luis G. 
Published: July 2010

AbstractThe adsorption of CO2 on LaCrO3 in the temperature range 273–675 K was studied. The equilibrium data were analysed according to Freundlich's model. Firstly CO2 chemisorbs, producing irreversible species which were identified as bidentate carbonates (infrared bands at 1660, 1650, 1631, 1306, 1220 and 1106 cm−1). Then CO2 is reversibly chemisorbed as a free carbonate ion (infrared band at 1423 cm−1); the high coverages observed at lower temperatures suggest some participation of physical adsorption in the reversibly adsorbed CO2. Entropy calculations showed that these adsorbed species are best described by a mobile model which assumes two translational and two rotational degrees of freedom. Carbonates produced after CO2 adsorption on LaCrO3 are more difficult to remove than carbonates formed on LaCoO3. This provides a possible explanation for the low catalytic activity for CO oxidation of the former oxide as compared with the activity of the latter. After pyridine adsorption, Lewis bands in the infrared region at 1606, 1595, 1490, 1440 and 1220 cm−1 were observed. After adding water no Brönsted bands were found.
The synthesis of pyrazolo‐ and isoxazolo‐[3,4‐c]‐pyrazole hemiazadicarbocyanine dyes
Authors: Koraiem Ahmed I. M. 
Published: July 2010

AbstractNew substituted pyrazolo and/or isoxazolo‐[3,4‐c]‐pyrazole hemiazadicarbocyanine dyes (IVa‐d, Va‐d, VIa‐d) were prepared via the synthesis of 4‐arylidino‐1‐phenyl‐3‐benzoxazolium‐2‐yl‐pyrazol‐5‐one (IIa‐d) followed by their interaction with hydrazine hydrate, phenylhydrazine and hydroxylamine. Structures of the synthesised compounds were determined from analytical data and from spectra. The biological activity of IV, V and VI were tested against bacteria and fungi.
Production of xylose, furfural, fermentable sugars and ethanol from agricultural residues
Authors: Singh Amar , Das Kumudeswar , Sharma Durlubh K. 
Published: July 2010

AbstractWith the developing shortage of petroleum, reliance on biomass as a source of chemicals and fuels will increase. In the present work, bagasse and rice husk were subjected to dilute acid (H2SO4) hydrolysis using pressurised water to obtain furfural and fermentable sugars. Various process conditions such as particle size, solid‐liquid ratio, acid concentration, reaction time and temperature have been studied to optimise yields of furfural, xylose and other fermentable sugars. The use of particle sizes smaller than 495 μm did not further increase the yield of reducing sugars. A solid‐liquid ratio of 1:15 was found to be the most suitable for production of reducing sugars. Hydrolysis using 0.4% H2SO4 at 453 K resulted in selective yields (g per 100 g of dried agricultural residues) of xylose from bagasse (22.5%) and rice husk (21.5%). A maximum yield of furfural was obtained using 0.4% H2SO4 at 473 K from bagasse (11.5%) and rice husk (10.9%). It was also found that hydrolysis using 1% H2SO4 at 493 K resulted in maximum yields of total reducing sugar from bagasse (53.5%) and rice husk (50%). The reducing sugars obtained were fermented to ethanol after removal of furfural. The effect of furfural on the fermentation of sugars to ethanol was also studied. Based on these studies, an integrated two‐step process for the production of furfural and fermentable sugars could be envisaged. In the first step, using 0.4% H2SO4 at 473 K, furfural could be obtained, while in the second step, the use of 1% H2SO4 at 493 K should result in the production of fermentable sugars.
Synthesis and antibacterial activity of some new diarylsulphides and diarylsulphones containing azetidin‐2‐one and/or diazetidin‐2‐onyl moities
Authors: Abbady Mahmoud A. , El‐Kahef Hussein S. , Abd‐Alla Mohamed A. , Kandeel Maymouna M. 
Published: July 2010

AbstractCyclonucleophilic addition of N‐phthaloylaminoacid chlorides (II on 4‐(N‐ary‐lideneamino)‐4′‐nitrodiphenyl sulphides (I) in dioxane and triethylamine afforded 4‐(4″‐aryl‐3″‐phthalylamino‐2″‐oxo‐azetidin‐1″‐yl)‐4′‐nitro‐diphenyl sulphides (III). Hydrazinolysis of III yielded 4‐(4″‐aryl‐3″‐amino‐2″‐oxo‐azetidin‐1″‐yl)‐4′‐nitro‐diphenyl sulphide hydrochlorides (IV). Condensation of IV with anisaldehyde using ethanol and piperidine as a basic catalyst gave 4‐(4″‐aryl‐3″‐anisylidine amino‐2″‐oxoazetidin‐1″‐yl)‐4′‐nitrodiphenylsulphides (V) in good yields. Interaction of V with chloroacetyl chloride in dioxane and triethylamine produced 4‐(4″‐aryl‐3″‐substituted β‐lactamyl‐2″‐oxo‐azetidin‐1″‐yi)‐4′‐nitrodiphenyl sulphides VI. Oxidation of IV, V and VI using hydrogen peroxide/glacial acetic acid mixtures gave the corresponding sulphones (VII), (VIII) and (IX). Sulphones of the type IX were obtained by unequivocal synthesis through interaction of sulphone‐anils VIII with chloroacetyl chloride. The antibacterial activities of some of these compounds were determined.
The effect of inverted micelles adsorbed on different metals on the hydrolysis of methyl salicylate and ethyl acetoacetate
Authors: Iwunze M. O. , Nnodimele R. 
Published: July 2010

AbstractHydrolysis of methyl salicylate was carried out on inverted micelles adsorbed on copper. The initial rate of hydrolysis was found to be a linear function of the surfactant concentration and copper surface area. However, the initial rate was found to be linear only at low surfactant concentrations for a fixed surface area of copper, and reached a maximum at higher concentrations. Cetyltrimethylammonium bromide (CTAB) was found to be a better catalyst both in the ordinary micelle and in its inverted form than the corresponding Hyamine surfactant. The effect of different metals on the initial rate of ethyl acetoacetate hydrolysis was investigated. An enhanced rate of hydrolysis was observed on the selected metals used (Al, Cu. Pb and Sn) and the magnitude of the rate enhancement was observed to be dependent on the potential of zero charge (pzc) of these metals.
Correction factors for the dynamic measurement of the volumetric mass‐transfer coefficient
Authors: Spriet J. A. , Botterman J. H. 
Published: July 2010

AbstractThe experimental determination of the volumetric mass‐transfer coefficient based on the use of an oxygen electrode requires a mathematical model of the experimental system and a parameter estimation method to obtain a number for the kta value. Previous work has resulted in a number of different model structures corresponding to different hypotheses concerning the relevant physical phenomena. Little is known about the impact of a specific choice for the model structure or that of the estimation procedure on the numerical value of the mass‐transfer estimate. This impact is investigated here and guidelines are given for the choice of a parameter estimation scheme. In addition, correction factors that measure the impact of a structural choice are given for both the moment and least squares parameter estimation methods. The diagrams may be used in a preliminary phase to make an overall appraisal of the specific experimental conditions and in the estimation phase to reduce computational loads.
Permeation of benzene through liquid surfactant membranes
Authors: Goswami Amar N. , Rawat Bachan S. 
Published: July 2010

AbstractThe effect of time on the permeation of benzene through aqueous surfactant membranes formed with two non‐ionic surfactants has been studied on a batch scale under two different conditions of surfactant concentration and hydrocarbon: water ratio in the emulsions. The data have been correlated by an equation based on Casamatta's model of hydrocarbon permeation from an emulsion drop. The results indicate that the correlation can be used to treat the data until the onset of membrane rupture. The membrane thickness depends on the hydrocarbon: water ratio in the emulsion, and varies from about 1.57 to 5.10 μm.
Desiccant efficiency in solvent and reagent drying 8. molecular sieve column drying of 95% ethanol: An application of hygrometry to the assay of solvent water content
Authors: Burfield David R. , Hefter Glenn T. , Koh Donald S. P. 
Published: July 2010

AbstractThe use of hygrometry for the measurement of ethanol water content and the application of molecular sieves for column drying of 95% ethanol are described. The commercial hygrometer used in this study permitted measurement of water content in the range 0.005–5% (by vol) but was subject to a number of limitations which made measurements more time‐consuming than anticipated. Grossly wet ethanol containing 5% (by vol) water was readily dried to a water content of about 0.3% (by vol), by treatment with a column of 3A molecular sieves. Slow flow rates enhanced the drying action, which was largely independent of the column dimensions and scale of the drying process. Water breakthrough occurred when water adsorption by the sieves exceeds about 10% (by wt).
Kinetics of catalytic esterification of propan‐1‐ol with propanoic acid using cation‐exchange resin
Authors: Dakshinamurty P. , Ramarao M. V. S. , Ramachandramurty Ch. V. 
Published: July 2010

AbstractThe kinetics of liquid phase esterification of propan‐1‐ol with propanoic acid catalysed by Dowex‐50W cation‐exchange resin in the H+ form have been studied in a batch reactor. The effects of catalyst concentrations, mol ratios and temperatures on the conversion were studied. An empirical correlation relating the specific reaction rate constant in terms of these variables has been developed, and a mechanism proposed on the lines of the Langmuir‐Hinshelwood model. The effect of different catalysts on the conversion is compared.
Hydration of magnesium oxides in the presence of water vapour
Authors: Bhatti Asif S. , Dollimore David , Dyer Alan 
Published: July 2010

AbstractThe uptake of water vapour on to magnesium oxide has been studied using a silica spring technique. In the experiment reported here, porous magnesium oxides were investigated, and the amount adsorbed at equilibrium at various vapour pressures of water was determined. The magnesium oxides used were characterised using low temperature nitrogen adsorption to give a pore size distribution and a specific surface area, and chemical analysis from X‐ray fluorescence data. The nitrogen adsorption isotherms obtained were a mixture of type II and type IV using the BET classification. The oxides sorbed water vapour to give an equilibrium isotherm which was sigmoid in character. Rehydration of the samples after desorption and degassing at 298 K produced samples with an enhanced capacity for water vapour sorption. This is associated with a change in the surface of the oxide from a hydrophobic to a hydrophilic character upon the second adsorption cycle. This is of importance in assessing the water sorption capacity of industrial produced porous magnesium oxides and their subsequent use as desiccants.
Studies on an araldite‐based membrane of copper hexacyanoferrate (III) as a caesium ion‐sensitive electrode
Authors: Jain Ajay K. , Singh Raj P. , Bala Chand 
Published: July 2010

AbstractSolid membranes of copper hexacyanoferrate (III) in araldite are evaluated as a caesium ion‐sensitive electrode. The electrode can be used for caesium determination in the concentration range of 10−1 to 10‐4M. The potentials generated across the membrane are reproducible and steady potentials are attained in about 1 to 2min. The same electrode can be used over a period of 6 months without significant change in potential. The electrode can be used in the pH ranges 2.5–6.0 at 10−2 M Cs+ and 3.0–6.0 at 10−3 M CS+, and in presence of a number of interfering ions. Potentiometric titration of caesium nitrate with 12‐moIybdophosphoric acid was also carried out using the membrane as an end point indicator.
Comparative study of the activity of cobalt and nickel as promoters of HDS catalysts
Authors: Laine J. , Severino F. , Golding R. 
Published: July 2010

AbstractA series of trimetallic (NiCoMo) hydrodesulphurisation supported catalysts were prepared using a successive impregnation method, varying the ratio of promoters Ni/(Ni + Co) and maintaining the ratio (Ni + Co)/Mo constant. Optima for higher thiophene hydrodesulphurisation activity were found for ratios Ni/(Ni + Co) of 0.7 and 0.8. It is suggested that the optima may be strongly dependent on method of catalyst preparation, and/or type of support employed. Presulphidation was found to increase the activity in NiMo more than in CoMo. Testing of commercial catalysts confirmed various differences between CoMo and NiMo catalysts.
The kinetics of hydrodesulphurisation of thiophene over a nickel‐molybdenum catalyst
Authors: Sharma Nagesh , Chakraborty Purnanand , Kar Anil K. 
Published: July 2010

AbstractThe kinetics of vapour phase hydrogenolysis of thiophene over a series of unsupported and γ‐alumina supported nickel‐molybdenum catalysts were studied at atmospheric pressure using a fixed bed integral microreactor. A kinetic expression describing the effects of temperature and space velocity was experimentally verified. The hydrogenolysis of thiophene was found to be 0.8th order with respect to thiophene and 0.8Sth order with respect to hydrogen. The activation energy of the reaction over nickel‐molybdenum (NiO:MoO3 weight ratio 30:70) catalyst was found to be 19.23 kJ mol−1 in the temperature range 250–350°C, while above this temperature the reaction was affected by adsorbed thiophenic sulphur. X‐ray and infrared analyses of the catalysts indicated that MoO3 (Mo6+, a main component), which after pretreatment forms MoS2 or MoS2+MoO2, requires the incorporation of a specific concentration of nickel (Ni:Mo ca 0.5) in the form of α‐NiMoO4 for maximum hydrodesulphurisation activity.