bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies of the effects of electrolytes on the rates of precipitation of calcium sulphate dihydrate using an ion‐selective electrode
Authors: Mile Brynmor , Vincent Arthur T. , Wilding Christopher R. 
Published: July 2010

AbstractA calcium ion selective electrode has been used to follow the acceleration of the rate of precipitation of calcium sulphate dihydrate by inorganic electrolytes at 15, 25 and 35°C. At zero and low added electrolyte concentrations, the rate of precipitation is strictly proportional to the square of the supersaturation, has an activation energy 75 kJ mol−1in agreement with previous studies and is indicative of a surface diffusion controlled process. However, with electrolytes containing sulphate ions in excess of 0.05 mol dm−3marked departures from a square law are observed; the rate is best represented as the sum of a square and first order term in supersaturation, the first order term becoming dominant at concentration ofc.0.1 mol dm−3. Under these conditions the rate has an activation energy (29 kJ mol−1) which is close to that for the volume diffusion of ions in aqueous solutions and indicates that the surface process has been accelerated to such an extent that the diffusion of ions from solution to the crystal face has become the slowest and, hence, the rate controlling step. It appears that the electrolytes accelerate the surface process by increasing the rates of dehydration of the calcium and sulphate ions at the interface.
Magnetic and catalytic properties of sintered nickel catalysts for the methanation reaction
Authors: Everson Raymond C. , Mulay Laxman N. , Mahajan Om P. , Walker Philip L. 
Published: July 2010

AbstractNi catalysts supported on Al2O3, as received commercially and subjected to sintering at 723–973 K, were characterised in terms of distinct magnetic structures. It was found that the Ni on all the catalysts consisted of a mixture of single domain structures, with and without anisotropic effects, and multidomain (ferromagnetic) structures. The formation of the multidomain particles during the sintering process coincides with a decrease in catalytic activity for the reaction CO+3H2°CH4+H2O. From this study it was concluded that the methanation reaction is ‘magnetic‐structure’ sensitive.
Application of flyash instead of activated carbon for oxalic acid removal
Authors: Jain Kamal K. , Prasad Gur , Singh Vishwa Nath 
Published: July 2010

AbstractFlyash, a waste product from thermal power plants, has been used as an adsorbent for the removal of oxalic acid. The adsorption process follows first‐order kinetics and the equilibrium is attained within 30 min in the concentration range studied (0.01‐0.1M). The adsorption obeys both the Freundlich and Langmuir isotherms and the constants have also been reported for flyash and activated carbon. At low concentrations, the increase in pH with flyash is comparatively more than for activated carbon. There seems to be a good scope for the use of flyash in place of activated carbon as an adsorbent for oxalic acid removal.
The extraction of anionic complexes of divalent manganese, cobalt, nickel and copper from aqueous thiocyanate solutions by tricaprylmethylammonium chloride
Authors: Sato Taichi 
Published: July 2010

AbstractThe extraction of divalent manganese, cobalt, nickel and copper‐thiocyanato anionic species from aqueous solutions by tricaprylmethylammonium chloride (R3R′NCl) in benzene has been investigated under different conditions. Both the aqueous and organic phases have been examined by spectrophotometry. Infrared spectro‐photometry and measurements of water content, apparent molecular weight and magnetic moment have been applied to the organic extracts, and electron spin resonance experiments to the organic manganese(II)‐ and copper(II)‐complexes. The mechanism of the extractions and the structures of the extracted complexes are discussed on the basis of the results obtained. As a result, it is found that although the extraction efficiency follows the order Co > Cu > Mn > Ni, the extraction of divalent transition metals is expressed as [M(NCS)4]2‐(aq) + 2R3R′NNCS(org)→(R3R′N)2‐[M(NCS)4](org) + 2NCS‐(aq) in which M = Mn, Co, Ni and Cu. The extracted species of divalent manganese, cobalt and nickel give a tetrahedral Td symmetry, and the copper(II) species is in a distorted tetrahedron (point group D2d symmetry). In addition the species of nickel (II) extracted at low aqueous concentration exists as a complex (R3R′N)2[Ni(NCS)4(H2O)2] in an octahedral arrangement.
Ternary phase equilibrium data for the systems: Glycerol‐water‐alcohols
Authors: Patel Amrit N. 
Published: July 2010

AbstractPhase equilibrium data for glycerol with water and n‐butyl, sec‐butyl, isobutyl, tert‐amyl, cyclohexyl and benzyl alcohols are presented and used to evaluate the possibility of employing distribution of glycerol between water and these solvents as a means of separation of glycerol from aqueous solutions. n‐Butyl alcohol offers the best hope of achieving separation of glycerol by distribution between n‐butyl alcohol and water. However, the separation factor is only modest and there will be a consequent need for a large number of contacting stages.
Kinetics of propellant decomposition
Authors: Kishore Kaushal , Kashyap Arun K. , Prasad Ganga 
Published: July 2010

AbstractEquations for solid‐state decompositions which are controlled by the phase‐boundary movement and nucleation have been examined using ammonium perchlorate/polystyrene propellant decomposition at 503 K and 533 K. It was found that 3 different equations governed by the nucleation process show a good fit of data at these temperatures. However, the best fit was obtained for the following Avrami‐Erofeev equation, [‐In (1 ‐ α]1/4=kt.
Foam separation and precipitate flotation. The problem of surfactant recovery and reuse
Authors: Charewicz Witold A. , Strzelbicki Jerzy 
Published: July 2010

AbstractAn experimental investigation is presented on the recovery of cationic [dimethyl‐benzyldodecylammonium bromide (DMBDA‐Br)] and anionic [sodium dodecyl‐benzylsulphonate (Na‐DBS)] surfactants from foam separation and precipitate flotation concentrates. DMBDA‐Br was recovered and reused fr m the concentrate of foam separation of perrhenates with recovery of over 90% by applying coacervation by potassium thiocyanate. Na‐DBS was recovered and reused from the concentrate of precipitate flotation of copper hydroxide with recovery over 90% by applying precipitation with dodecylbenzylsulphonic acid from solution of concentrate dissolved in sulphuric acid at pH range from 1.0 to 2.5. Recovered surfactants were found efficient for subsequent flotation processes.
Extraction of oily matter from spent bleaching earth with water at elevated temperature and pressure
Authors: Penninger Johannes M. L. 
Published: July 2010

AbstractContacting spent bleaching earth with water at 473–523 K under saturated steam pressure and subsequent gravity settling results in a complete separation of earth and fatty matter. A top layer of extracted fatty material is formed, floating on water with the extracted earth precipitated in the water layer on the bottom of the container. The extracted earth is virtually free of fatty material with an oil content of 0.5% wt or less; the fatty matter extracted consisted mainly of free fatty acids and, upon vacuum distillation yielded 65 to 75% wt of distilled fatty acids.
Dissociation constants of long chain fatty acids in methanol‐water and ethanol‐water mixtures
Authors: Rahman Muhammad A. , Ghosh Ashim K. , Bose Rathindra N. 
Published: July 2010

AbstractThe pKavalues of lauric acid, myristic acid, palmitic acid and stearic acid in methanol‐water and ethanol‐water mixtures of different compositions at 303 K and ionic strength,I=0.1M(KNO3) have been determined. The pKavalues of the fatty acids have been found to increase with the alcohol content of the solvent. It has also been found that, in general, the pKavalues in the ethanolic solvent are greater than those in the methanolic solvent. In a given solvent mixture the observed pKavalue decreases in the order of stearic acid > palmitic acid > myristic acid > lauric acid. Departure from the predicted linearity of the plots of pKaagainst the inverse of the dielectric constant, 1/Dindicates that the electrostatic effects taken into account by the Born theory are not adequate enough to represent the total medium effects on pKa.
Improvements to the von Miller‐Kinkelin reaction. Synthesis of 3‐methylquinolines and of 3‐isopropylquinoline
Authors: Claret Paul A. , Osborne Alan G. 
Published: July 2010

AbstractThe use of an ethanolic reaction medium with iron (III) chloride and zinc chloride as condensing agents with dropwise addition of reactants gives improved yields in the von Miller‐Kinkelin synthesis of 3‐methylquinolines. A convenient one‐step synthesis of 3‐isopropylquinoline is reported. N.m.r. spectral data are presented.
Solvent extraction used in industrial separation of rare earths
Authors: Brown Clifford G. , Sherrington Leonard G. 
Published: July 2010

AbstractThe total reflux method as applied to the separation of rare earth elements is outlined with reference to extractants Versatic 911, tributyl phosphate and di‐2‐ethylhexyl phosphoric acid. Industrial solvent extraction processes are described for the production of pure compounds of lanthanum, praseodymium, neodymium, samarium, europium, gadolinium and yttrium.
Choice and design of solid ion exchange plants for the recovery of uranium
Authors: Naden David , Bandy Martin R. 
Published: July 2010

AbstractThe selection of an extraction process for uranium recovery from milled ore leach solutions, in‐situ leach solutions, mine waters and by‐product streams is one which cannot be made without taking into account the effect of the extraction process on the remainder of the process and on the environment. The factors affecting the selection and the choice of solid ion exchange in recoveries from the whole range of process situations are discussed and it is concluded that both resins and equipment exist which satisfy most process needs. Further developments are however required if the full potential of resin ion exchange to influence uranium recovery flowsheets is to be realised. The usefulness and flexibility of solid ion exchange results from the ability of resins to recover uranium from solutions containing up to 30% suspended solids, thereby reducing post‐leach capital cost, and their zero solubility which in some cases reduces both operating costs and contamination of the process stream and the environment. The correct choice of contactor and resin has required the development of techniques of resin evaluation and prediction of contactor performance. In addition, the rapid increase in uranium demand has required the development of reliable methods of process design based on the results from laboratory tests using small volumes of solution and these must often be sufficiently reliable to construct a full scale plant without the extensive pilot plant activity of the past. The successful techniques used have been based on R and D work at various centres of the technology and have proved to be important in assisting the industry to respond rapidly to market demands with extraction equipment designed to fit modern low cost flowsheet requirements.
Continuous ion exchange using magnetic shell resins. I. Dealkalisation—laboratory scale
Authors: Bolto Brian A. , Dixon David R. , Swinton Everard A. , Weiss Donald E. 
Published: July 2010

AbstractA completely novel technique of continuous ion exchange has been developed, which uses ion exchangers prepared by grafting an active shell onto a magnetic polymeric core. In the magnetised form, the ion exchange resin beads clump together in the form of large flocs, with sedimentation velocities many times those of the individual beads. Small beads may then be used in fluidised or semi‐fluidised beds, at liquid flow rates equal to or greater than conventional ion exchange systems, but with the advantage of rapid reaction rates and attainment of equilibrium. A major practical advantage is that even as a settled bed the magnetised ion exchange resin remains semifluid, and can be pumped with practically no attrition. Utilising these properties, a truly continuous ion exchange system has been built for the process of dealkalisation, comprising a single stage fluidised adsorber and a compact moving bed regenerator which develops multistage contact. Transfer of ion exchanger between each vessel is effected by means of two peristaltic pumps. This paper summarises the results obtained in a laboratory sized apparatus, treating a hard, alkaline water at a superficial velocity of 30 m h−1, and demonstrates the potential for a system utilising a fraction of the volume of ion exchange resin employed in a conventional system, in a simple robust plant with no valves, no screens, no pressure vessels and only one electrical level control.
Continuous ion exchange using magnetic shell resins. II. Dealkalisation—pilot plant study
Authors: Anderson Nevil J. , Dixon David R. , Swinton Everard A. 
Published: July 2010

AbstractFrom the results obtained in the treatment of a number of hard, alkaline feed waters in a pilot scale dealkalisation plant, it has been shown that the use of a magnetic carboxylic acid resin in a fluidised bed has definite advantages over conventional systems. Less resin is needed and simpler plants can handle the same throughput of raw water whilst maintaining the same quality of product. Plant operation is truely continuous without any complex valve system or pressurised vessels.
Equipment development in solvent extraction
Authors: Murray David J. 
Published: July 2010

AbstractAny solvent extraction system must ultimately involve mixing and phase separation. The mixer‐settler, which is the chief subject of this paper, has several advantages. It can be readily scaled up to handle large flow rates, and there is a great deal of practical experience in using it. There are also a number of areas where it can be modified to give improved operation. The mixer is an ideal area to apply the knowledge of chemical reactor fundamentals. The stage efficiencies to which we commonly refer can also be viewed primarily as mixer efficiencies. It would be a logical matter to consider increasing the degree of chemical reaction by using mixers in series within each stage. The physical phenomena taking place within the settler become clear with investigation. The assumption that plug flow predominates in any settler is probably at variance with actual facts. The control of the flow of the dispersion in the settler is a factor which should serve to make settlers smaller and more efficient. Solvent extraction equipment is undergoing constant scrutiny and improvement. The conventional mixer still needs additional basic studies, but it may some day be replaced by some other basic method of imparting mechanical energy and flow. It is likely that the gravity settler may be replaced by a device using a more intense force field, such as electrostatic or centrifugal forces.
Studies with chromium ferricyanide epoxy resin‐based membranes
Authors: Srivastava Suresh K. , Jain Ajay K. , Agrawal Sushma , Singh Raj P. 
Published: July 2010

AbstractThe solid membrane of chromium ferricyanide in epoxy resin has been used as a silver sensitive electrode. The electrode response to silver ions is non‐Nernstian, but a linear plot has been obtained in the concentration range 10−1‐10−3M with a slope of 46 mV per decade of activity. The response time of the electrode is a few seconds and potentials generated are reproducible. The electrode is not specific to silver ions but can nevertheless be used in presence of Hg2+, Zn2+ and Cd2+. Anions show no interference. Silver can be estimated even in the presence of interfering ions by potentiometric titration using the membrane as an end point indicator electrode.
Steady state growth kinetics of Chlorella vulgaris under double substrate (urea and phosphate) limitation
Authors: Panikov Nicolai 
Published: July 2010

AbstractChange from phosphate‐limited growth to nitrogen‐limited growth at a fixed specific growth rate (μ) was investigated. To account for the specific growth rate control by the two substrates there was little to choose between a relation involving both substrate concentrations and one which involved only the substrate concentration which, by itself, gave the minimum value to μ. Double substrate limitation of growth was manifested by variations in the nitrogen and phosphorus contents of the biomass over a considerable range of urea and phosphate concentrations in the culture medium at a given growth rate. These changes in the elementary composition of the biomass were accounted for by the theoretical model of Panikov and Pirt.
Studies on petroleum sulphonates: Correlation between their chemical structure and the oil—Water emulsion stability characteristics
Authors: Anand Onkar N. , Neemla Kalyan D. , Malik Ved P. 
Published: July 2010

AbstractThe average molecular weight distribution, emulsion stability of oil—water emulsion, the chemical structure of the hydrocarbon portions of petroleum sulphonates, and surface active properties have been determined with a view to establishing a correlation between the chemical structure of petroleum sulphonates and their emulsion stability characteristics. It has been found that the emulsion stability of oil—water emulsions imparted by sodium petroleum sulphonates depends on: (i) average molecular weight of sodium petroleum sulphonates; (ii) their molecular weight distribution; (iii) oil—water interfacial tension; (iv) hydrophile—lipophile balance values. The structural parameters which predominantly effect the emulsion stability are the ratio of the percentage distribution of carbon atoms in paraffin side chains to the percentage distribution of carbon atoms, the aromatic rings (CP/CA), the relative proportions of long chain mono‐aromatics and the orientation of the sulphonate group relative to the paraffin alkyl chains in the molecules.
A g.l.c. simulated distillation technique to study changes in the composition of coke‐oven road tars in service
Authors: Jamieson Ian L. , Hattingh Maria M. , Edler Anthony C. 
Published: July 2010

AbstractA simulated distillation technique has been developed making use of gas‐liquid chromatography (g.l.c.) for the quantification of oils present in road tars derived from coke‐oven crude tars. The tar‐oil constituents are grouped into boiling temperature ranges which coincide with those of fractions or cuts used in a standard (conventional) distillation test. The g.l.c. method caters for the wide range in boiling temperatures of tar‐oil constituents and for the fact that only about half of the tar substance injected is eluted from the column. In the analyses of tars recovered from road surfaces a means has been found to compensate for the presence of detritus in the tar. This method has several important advantages over the standard distillation procedure. Its accuracy and precision are superior and it can be used to determine constituents boiling as high as 400°C (673 K). (Due to the thermal sensitivity of coal tar hydrocarbons, the temperature in the standard distillation test may not exceed 340°C.) The g.l.c. method is more rapid and the small amount of tar required facilitates the analyses of tars weathered in road surfaces. In addition, repeat analyses can be carried out without inconvenience and the handling of the tar material is reduced. The g.l.c. method provides a powerful research tool for the study of the weathering of road tars. This paper gives the results of some weathering investigations. These show that even constituents with high boiling points (in the range 370–400°C) may be partially lost from tars in the first year of service. Oil losses are most rapid in the first year, but all constituents with boiling points below 300°C may be lost after prolonged service. From data provided by this method and measurements of the change in viscosity of tars on weathering, it has been possible to conclude that, in the case of coke‐oven tars, evaporation is the major weathering mechanism in the South African Highveld climate. There is a good correlation between oil losses and the hardening of tars, particularly in the early life of a spray‐and‐chip surfacing. Such studies have led to the development of improved road tar binders with economic benefit to the South African road industry.
Kinetics of pyrolysis of pure and doped cobalt oxalate
Authors: Rao Chebrolu Rama Mohan , Mehrotra Pratap N. 
Published: July 2010

AbstractThe object of the present work was to illustrate the effect of impurities on the kinetics and energetics of the thermal decomposition of pure cobalt oxalate. Cationic impurities like Mg2+, Mn2+, Fe2+, Ni2+, Cu2+, Zn2+, Cd2+, Pb2+, Zr4+ have been introduced into pure cobalt oxalate dihydrate and differential thermal analysis has been used to determine the enthalpy and energy of activation for the decomposition reaction of pure and doped samples.
The permeation of hydrocarbons through a polyethylene membrane
Authors: Peeters Hugo , Vanderstraeten Peter , Verhoeye Lucien 
Published: July 2010

AbstractPermeation data of a number of linear, branched and cyclic hydrocarbons have been determined up to a pressure of 70% of the saturation vapour pressure and a temperature range of 30–50°C. The concentration of solvent in the membrane at the liquid site has been determined by desorption. An average diffusion coefficient has been computed assuming the liquid concentration in the membrane at the permeate side to be zero. The activation energy of the permeation has been correlated with molecular structure.
Copper extraction from diluted sulphate solutions by 2‐hydroxy‐5‐tert‐butylbenzaldehyde oxime
Authors: Stpeniak‐Biniakiewicz Danuta , Szymanowski Jan 
Published: July 2010

AbstractA study of the influence of the equilibrium pH of the aqueous phase and the oxime concentration in octane, isooctane, xylene and ethylene dichloride showed that 2‐hydroxy‐5‐tert‐butylbenzaldehyde oxime (HBBO) forms a yellow complex with copper with a molar ratio of ligand: metal equal to 2:1. The same results were obtained using Job's and slope ratio methods. The diluents examined influence the copper extraction by HBBO, especially at low pH values in the aqueous phase. The order of extractability is as follows: isooctane=octane>xylene>ethylene dichloride. At low pH values, HBBO shows greater extraction power than 2‐hydroxy‐alkyl‐benzophenone oximes. Computer calculations suggest that polymerisation of the complex does not occur. However, a solvation of the complex occurs when excess of the oxime is used.
Ternary liquid‐liquid equilibrium in tetrahydrofuran‐water‐solvent systems
Authors: Coca José , Díaz Ramona M. 
Published: July 2010

AbstractTernary liquid—liquid equilibrium data for tetrahydrofuran, water and benzene, n‐heptane, methylcyclohexane, trichloroethylene and perchloroethylene were investigated at 298 K (25°C). Equilibrium data have been correlated using Hand, Othmer—Tobias and Bachman equations; plait points have been estimated by the methods of Treybal et al. and Mato‐Bueno. Trichloroethylene and perchloroethylene show isopicnic compositions and n‐heptane, benzene and methylcyclohexane show the highest selectivities.
Experience with a pilot‐scale electro‐organic synthesis process
Authors: King Christopher J. H. 
Published: July 2010

AbstractA description is given of the preparation of 4,4′‐dihydroxyhydrobenzoin from p‐hydroxy‐benzaldehyde by electrohydrodimerisation in both bench and pilot‐scale cells. The irreproducible performance of a cadmium cathode was avoided by using mercury in a simple and reliable cell.