bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of sample thickness on the formation of sodium trimetaphosphate
Authors: Lee J. D. , Bond A. H. 
Published: July 2010

AbstractThe conditions for preparing sodium trimetaphosphate by heating monosodium orthophosphate dihydrate have been studied. It has been found that the use of thicker samples allows a lower temperature and a shorter heating period to be used. Sodium trimetaphosphate of very high purity can be prepared by heating a sample 2·4 cm. thick for 1/2 hour at 500°.
Influence of amorphous silica on the hydration of tricalcium aluminate
Authors: de Jong J. G. M. , Stein H. N. , Stevels J. M. 
Published: July 2010

AbstractAmorphous silica influences tricalcium aluminate (C3A) hydration both in pastes and in suspensions.Two heat peaks are found by isothermal calorimetry during the paste hydration of C3A. The addition of amorphous silica causes the second heat peak to shift towards shorter reaction times and become more pronounced.In suspensions, the change in ion concentration in the water phase is not influenced by the presence of amorphous silica except that the change in concentration occurs more quickly. Quantitative X‐ray analysis shows that more 3CaO.Al2O3.6H2O is present in suspensions containing amorphous silica than in silica‐free suspensions at equal hydration times.
The induced plasma torch as a high‐temperature chemical reactor. I. Oxidation of silicon tetrachloride
Authors: Audsley A. , Bayliss R. K. 
Published: July 2010

AbstractFour torches of different design were constructed and evaluated. Injection of silicon tetrachloride vapour directly into the plasma resulted in instability and rapid extinction of the latter when the reagent flow rate exceeded 4 g/min. In the preferred design, the reagent was injected into the plasma tail flame through radial ports. With this system silicon tetrachloride was completely oxidised at a flow rate of at least 67 g/min.
Kinetics of the dissolution of uranium dioxide in nitric acid. II
Authors: Shabbir Muhammed , Robins R. G. 
Published: July 2010

AbstractThe kinetics of the dissolution of uranium dioxide in nitric acid were investigated at temperatures up to 150° and oxygen and argon gas pressures up to 1150 psig. A mechanism for the high‐pressure process is proposed which is consistent with experimental reaction rates and the mechanism proposed previously for temperatures below 100°.
Isothermal vapour–liquid equilibria for the ethanol–n‐octane system
Authors: Boublikova Ludmila , Lu B. C.‐Y. 
Published: July 2010

AbstractA modified Dvorák & Boublík & recirculation still was used for the determination of isothermal vapour–liquid equilibrium data for the binary system ethanol–n‐octane at four temperatures. Liquid activity coefficients, γ, were evaluated, and log γ values were correlated by a three‐constant Redlich–Kister equation. Binary azeotrope exists at all four temperatures and the mole fraction of ethanol in the azeotrope increases with increasing temperature.
Anti‐fouling paints. I. Theoretical approach to leaching of soluble pigments from insoluble paint vehicles
Authors: Marson F. 
Published: July 2010

AbstractA theoretical approach to the problem of how contact leaching anti‐fouling paints work is discussed; a possible mechanism is selected and applied to an idealised model of a paint film. A precise mathematical treatment is then attempted of the relationship between the leaching rate, the physical properties, and if applicable the chemical properties of the envisaged paint film and its environment. A mechanism previously proposed has been examined by this method. An equation is derived for an idealised paint film relating the leaching rate to the physical properties of the paint film and the leachate. It is assumed that the rate of solution of a soluble pigment from an insoluble vehicle is dependent only on the physical properties of the paint film and the diffusion of the solvated pigment through the exhausted matrix and the diffusion layer of leachate in direct contact with the surface of the paint. An equation is derived for an idealised paint film which relates the leaching rate to some physical properties of the paint film and of the leachate.The equation is shown to predict qualitatively the effect of most variables known to affect the leaching of contact leaching paints. Some evidence is given to support the quantitative prediction of the relationship between the pigment volume content and the initial leaching rate, the effect of dissolved pigment in solution on the leaching rate, the increase in leaching rate for a given temperature increase, and the effect of velocity of flow past the surface of the paint film.This method of approach would appear to be applicable to mechanisms and models bearing a closer resemblance to practical anti‐fouling paints. However, the mechanism proposed appears sufficiently well substantiated to be employed in the design of leaching experiments and their application to more practical problems, such as the formulation of anti‐fouling paints.The need of a more rigorous approach to the design of leaching experiments is indicated.
Liquid extraction of metals from sulphate solutions by alkylphosphoric acids. I. Equilibrium distributions of copper, cobalt and nickel with di‐(2‐ethyl hexyl) phosphoric acid
Authors: Brisk M. L. , McManamey W. J. 
Published: July 2010

AbstractLiquid‐liquid equilibrium data were obtained at 25° for the distribution of copper, cobalt and nickel between aqueous sulphate solutions and kerosene solutions of di‐(2‐ethyl hexyl) phosphoric acid (EHPA). Two mechanisms of extraction were observed. When the ratio (L) of organic phase equilibrium metal concentration to initial EHPA concentration was less than 0·1, the metals were extracted by the reaction:
equation image
and a correlation for the equilibrium distribution coefficients was obtained from the thermodynamic equilibrium relationship for this reaction, taking into account metal ion complexing in the aqueous phase. Ammonium hydroxide and sodium hydroxide were used as alkalis for pH adjustment and similar distribution coefficients were obtained with both when L was less than 0·1. For L greater than 0·1, metal‐EHPA polymers were also formed in the organic phase, a typical step in their formation being:
equation image
Equilibrium relationships were obtained from consideration of the equilibrium constants of the typical step and the reaction for monomer formation. The nature of the alkali used for pH adjustment influenced the distribution coefficients when L exceeded 0·1, higher distribution coefficients being obtained with sodium hydroxide than with ammonium hydroxide.
Formation of calcium plumbate: Kinetics and mechanism of reaction
Authors: Martini P. L. , Bianchini A. 
Published: July 2010

AbstractIn the presence of excess air the kinetics of reaction between CaO and PbO to form calcium plumbate are governed by the diffusion process described by Jander's kinetic model. The energy of activation of the process, as calculated from the Arrhenius equation, is 50 kcal/mol. In an air and nitrogen atmosphere (ratio 1:16) the reaction rate is 4–5 times slower.It has been shown that formation of calcium plumbate from pure CaO and PbO takes place between 600–800° without formation of intermediate compounds.From the results obtained it is deduced that the mechanism of formation consists of two main stages–diffusion between the CaO and PbO, substantially due to the more diffusible PbO, and chemical reaction in the presence of O2.
Flotation kinetics for calcite in a semi‐batch system
Authors: Tewari S. N. , Biswas A. K. 
Published: July 2010

AbstractFlotation kinetics of calcite in a semi‐batch froth flotation system corresponds approximately to a second‐order rate equation, the order varying between 1·60 to 2·40 for different particle sizes and aeration conditions. Rate constant increases slightly with decrease in particle size and sharply with increase in air flow rate. It is postulated that flotation rate should depend on the magnitudes of solid/liquid and liquid/gas interfacial areas, besides other physico‐chemical parameters.
Precipitate flotation. V. Extractive solvent sublation
Authors: Pinfold T. A. , Mahne E. J. 
Published: July 2010

AbstractThe new technique of precipitate flotation of the second kind is unique amongst flotation processes in that it requires no surfactant. This does have the disadvantage that the floated material is not supported on the surface and tends to redisperse into the solution. A layer of immiscible organic solvent containing either a surfactant, a complexing agent, or the original precipitant, leads to solubilisation and retention of the floated material. As this is quantitative, spectrophotometric examination of the organic layer may provide a means of analysis for the ion originally precipitated. Complete removal from solutions as dilute as 10−5 M is possible.
Formation and surface properties of electron emissive coatings. II. Thermal decomposition and sintering of single alkaline‐earth carbonates
Authors: Judd M. D. , Pope M. I. 
Published: July 2010

AbstractThe thermal decomposition of ‘Spec‐Pure’ calcium, strontium and barium carbonates has been studied by preparing a calcination series up to 1200°. 0·6 g samples were placed in the bucket of a spiral silica spring balance and heated under vacuum, at a rate of rise of temperature of 200 deg c/h. After reaching a set temperature, the specific surface and total pore volume of the cooled residue were calculated, using data obtained from the sorption of nitrogen at 77°k. The results indicated that the extent of the activation which accompanies thermal decomposition depends on the amount by which the Tammann temperature of the resulting oxide exceeds the temperature at which the maximum rate of decomposition occurred.Thermogravimetric and gas evolution studies on strontium and barium carbonates are also discussed in connexion with work reported in an earlier paper.
Factors responsible for the activity of precipitated iron fischer‐tropsch catalysts
Authors: Nandi S. P. , Saran T. , Mukherjee P. N. 
Published: July 2010

AbstractThree precipitated iron Fischer‐Tropsch catalysts of identical chemical composition but prepared from different source materials were studied by gas adsorption. Of the Hofer ‘inducted’ catalysts, the most active one was found to combine greater surface area with a preponderance of narrower pores, compared with the other two. The greater activity was found to be reflected in the ‘a’ factor (Elovich Equation) which was very large. The limitation of the energy of activation as a parameter for the activity of solid heterogeneous catalyst was illustrated in terms of ‘compensation effect’. The complex nature of adsorption kinetics was shown by the anomalous temperature dependence of ‘a’ as well as changes in the slope of q versus log t curves.
Vapour‐liquid equilibria for the systems: Methylcyclohexane‐n‐butanol and toluene‐n‐butanol
Authors: Seetharamaswamy V. , Subrahmanyam V. , Chiranjivi C. , Dakshinamurty P. 
Published: July 2010

AbstractIsobaric and isothermal vapour‐liquid equilibria have been determined for the binary systems: methylcyclohexane‐n‐butanol and toluene‐n‐butanol at 760 mm Hg total pressure and 90° using a modified Colburn still. The activity coefficients data were satisfactorily tested for their thermodynamic consistency by the method of Herington and a satisfactory correlation was also obtained through Wohl's three‐suffix Margules equations for both conditions of restraint in the case of both systems. Azeotropes were observed for both systems and both conditions of restraint.
Safe storage and transportation of some potentially hazardous materials
Authors: Lee P. R. 
Published: July 2010

AbstractMany materials which are stored and transported in bulk undergo exothermic decomposition or oxidation reactions at elevated temperatures. Such reactions may render them liable to spontaneous ignition if they are in sufficient quantity and at such a temperature that the rate of heat production exceeds the rate at which heat is able to be transmitted to the surroundings.Steady‐state thermal explosion theory has been used to predict safe storage and transportation (critical) masses at a series of temperatures for three representative types of self‐heating materials—baled wool, powdered ammonium nitrate and a solution of methylethyl ketone (2‐butanone) peroxide (40%) in dimethyl phthalate. The non‐steady‐state theory (reactant consumption admitted) has been used to estimate the time taken for these critical masses to reach the critical state at each temperature.The critical masses have been shown to be consistent with safety requirements at present accepted for the storage and transportation of the materials discussed. The estimates of the times taken by the critical masses to reach the critical state bring an added dimension to the critical mass calculations, and together these results constitute an advance over the present situation where safe limits have been deduced on a trial and error basis.The methods outlined may be used to estimate critical masses and induction periods for any other self‐heating material and may be relied upon to give results of the correct order of magnitude.
Dehydration of ethyl alcohol on alumina‐coated silica
Authors: Fahim R. B. 
Published: July 2010

AbstractCatalysts were prepared by precipitation of aluminium hydroxide on a wet silica gel. The dehydration of ethyl alcohol on catalysts varying in alumina content was studied at 307° using a flow system. The products of dehydration were ethylene, ether and water. The kinetics of the formation of ethylene followed the Langmuir‐Hinshelwood mechanism, while the formation of ether occurred according to the Langmuir‐Hinshelwood mechanism and the Rideal‐Eley mechanism simultaneously. The catalytic activity was controlled by the amount of aluminium on the surface. The rate constants were correlated with the surface nature of the catalysts.
Mechanical behaviour of bituminous waterproofing membrane systems
Authors: Marijs P. D. , Bonafont R. L. 
Published: July 2010

AbstractThe mechanical behaviour of waterproofing membrane systems composed of one or more layers of bituminous sheeting fully bonded together to form an integral layer has been studied and a theory has been evolved which allows membrane stresses and strains to be calculated as a function of the mechanical properties of the constituent materials and of the associated substrate movement. Allowance is made for the visco‐elastic effects of bitumen.It is concluded that the ability of membranes to accommodate substrate movement largely depends on the mechanical properties of the base fabrics used to reinforce bituminous sheetings, and this has been confirmed in controlled experimental work.The order of substrate movement that may be tolerated by a single‐layer fully bonded system was calculated for a number of conditions. The improved mechanical performance afforded by partial bonding was considered to be worthwhile.
An oscillating baffle column fitted with stator rings III. Hold‐up and drop distribution
Authors: Thomas W. J. , Weng P. K. J. 
Published: July 2010

AbstractA study of drop sizes and their distribution in a new extractor shows the distribution to obey a log‐normal law. Hold‐up of dispersed phase obtained manometrically is related to oscillation speed (N), relative flow‐rate (Qt) and phase flow ratio. Equations are proposed for prediction of d32 and Ψ from N and Qt. The incipient flood point can be established either from the graphs or equations.An equation proposed by Misek to correlate the relative flow‐rate of the phases, the interdroplet collision rate, and coalescence has been examined. Values of U0, the free fall velocity obtained indirectly by experiment from the Misek‐type equation, are compared with free fall velocities for single drops obtained by other workers. The system examined was water‐acetic acid (solute)‐carbon tetrachloride (disperse phase).
An oscillating baffle column fitted with stator rings IV. interfacial area and mass‐transfer coefficients
Authors: Thomas W. J. , Weng P. K. J. 
Published: July 2010

AbstractStudies are reported on an oscillating baffle column fitted with stator rings with special reference to interfacial area.Pseudo point values of interfacial area are given along the extractor which together with values of mass‐transfer coefficient, Ka, enable pseudo point values of the coefficient for continuous and disperse phases, Kc and Kd, to be evaluated. The dependence of point and overall values of Kc, Ka and a (the overall interfacial area) on operating parameters are considered.
Degree of hydration of portland cement pastes with low water/cement ratios as influenced by curing conditions
Authors: Hanna K. M. , El‐Hemaly S. A. 
Published: July 2010

AbstractMeasurements of chemically combined water contents were made on Portland cement pastes made with water/cement ratios of 0.20 to 0.30 by weight. In addition to the factors involving water/cement ratio, curing medium, curing history and curing period, the degree of hydration of cement pastes cured at room temperature was significantly influenced by the availability of adequate water supply during the first 24 hours of the curing process.
Catalysis of graphitisation
Authors: Marsh H. , Warburton A. P. 
Published: July 2010

AbstractThe demand for graphites with specific properties and for an improvement in the economics of graphite production in recent years has led to an increased interest in catalytic graphitisation. At the present time, however, there is no review available of published studies and this paper attempts to make good this deficiency. Mechanisms whereby inorganic additives can catalyse graphitisation are considered, followed by a discussion of the mechanisms by which inorganic additives promote the graphitisation process. A comprehensive survey of the relevant literature to date is presented which describes in more detail the type of carbon used, the experimental techniques employed and the improvement obtained in graphite quality.
Vapour‐liquid equilibria of the carbon tetrachloride‐toluene system
Authors: Wang J. L. H. , Boublikova L. , Lu B. C.‐Y. 
Published: July 2010

AbstractThe vapour‐liquid equilibria of the system: carbon tetrachloride‐toluene were studied at five isothermal conditions by use of a modified Dvorak & Boublik circulation still. Liquid activity coefficients, γ, were evaluated. The values of γ were close to unity. The In γ values were correlated by a three‐constant Redlich‐Kister equation.
Reaction of isoprene with phenols catalysed by nickelocene and phenylmagnesium bromide
Authors: Suga K. , Watanabe S. , Kikuchi H. , Hijikata K. 
Published: July 2010

AbstractThe reaction of isoprene with phenol, catalysed by nickelocene and phenylmagnesium bromide, yields 2,2‐dimethylchroman, 2‐(3′‐methyl‐2′‐buten‐1′‐yl)phenol, 4‐(3′‐methyl‐2′‐buten‐1′‐yl)phenol, 2,2‐dimethyl‐8‐(3′‐methyl‐2′‐buten‐1′‐yl)chroman and 2,2‐dimethyl‐6‐(3′‐methyl‐2′‐buten‐1′‐yl)chroman. Reactions with other phenols were examined.
Fischer‐tropsch waxes v. Study of branching and its effect on crystallinity using an improved infra‐red method
Authors: Le Roux J. H. 
Published: July 2010

AbstractA method for the determination of degree of branching, much faster than the one previously used, is described. A sample cell designed for fast introduction and removal of samples is used and the method for measuring band intensities has been adapted to computer use.It is shown how the degree of branching decreases from the first member of a series of extract waxes to the residue, because of the higher solubility of isoparaffins compared with that of n‐paraffins. A linear relationship between crystallinity and degree of branching was found to exist for the series. Fischer‐Tropsch ‘medium wax’ exhibits an abnormally low crystallinity. Possible causes for this are the fact that it has a much lower average molecular weight than the extract waxes, which were derived from ‘hard wax’, and that there can be differences in chain‐length distribution.The extract waxes were found to contain 4–6% more amorphous material than isoparaffins, as determined by urea adduction. This difference is explained in terms of the tendency of the urea method to give too low values, the fact that some normal molecules can be present in amorphous regions and the uncertainty of the significance of infra‐red crystallinity in absolute terms.
High‐temperature oxidation of aluminium in various gases
Authors: Breakspere R. J. 
Published: July 2010

AbstractThe oxidation of high‐purity aluminium sheet in dry oxygen, moist oxygen, carbon dioxide and carbon monoxide (at total pressure 1.333 × 103 Nm−2) was studied in the range 673–923°K, using a vacuum microbalance to follow weight gains. 14CO2 and 14CO were used to elucidate the mechanism of the oxidation in these gases and to estimate the extent of carbon deposition in the oxide layer.The rate of oxidation in moist oxygen was similar to that in dry oxygen, the principle reaction being 2Al + 3H2O ← Al2O3 + 3H2.It is suggested that there are three steps in the reaction in CO2, viz. 2Al+3CO2 ← Al2O3 + 3CO, followed by 2Al + 3CO ← Al2O3 + 3C, and about 10% of the deposited carbon reacting further by 4Al + 3C ← Al4C3. Only the last two reactions are operative in carbon monoxide.The Arrhenius plots show a distinct break in the region 773–823°K for both carbon monoxide and carbon dioxide, but not for dry or moist oxygen. This is tentatively explained by a change in the rate‐determining process from diffusion via grain boundaries or cracks in the oxide, to lattice diffusion. It is suggested that carbon may become mobile in the oxide film between 773 and 823°K and may tend to congregate in the grain boundaries and cracks.The oxide film remained protective throughout the duration of the experiments in all the gases.
Effects of additives on graphitisability of carbons and graphite
Authors: Richards B. P. , Kellett E. A. 
Published: July 2010

AbstractThe effect of additives to the green mix on the subsequent graphitisability of various carbons and graphites has been studied using X‐ray diffraction techniques. The carbons have been characterised in terms of the structural parameters, La, Lc, d0002 and p.It is concluded that metallic iron (or sometimes other catalysing additives) produces little enhancement of graphitisability in materials which are known to be intrinsically graphitising on the Franklin scale (for example chars from PVC, petroleum and pitch).The cooking of petroleum, prior to mixing with a binder, is shown to predetermine the form that the coke will assume as the grist in the graphitised artefact. It is suggested as a consequence that it should be possible to investigate the effect that the grist and binder components have separately on the various physical properties of a heat‐treated artefact.It is shown that the addition of metallic impurities substantially enhances the degree of graphitisation and crystallinity attainable in a given heat treatment of classical non‐graphitising carbons (furan coke and cellulose). By contrast, for an archetypical graphitising material (PVC char), the crystallinity and structural perfection potentially attainable on heat treatment are considerably decreased as a result of the addition of sulphur.
Residence time distribution in continuous crystallisers
Authors: Hill S. 
Published: July 2010

AbstractThe theory of continuous crystallisation (especially of sucrose) in crystallisers connected in series, in which a suspension of growing crystals is fed forward through the system without backmixing, is presented, and the calculation of the minimum coefficient of variation that can be attained under stated conditions is described. Two cases specifically considered are: (1) stirred reactors of equal mean residence times connected in series, and (2) tubular reactors in which the residence time distribution is given by a Gaussian error function. Reduction of coefficients of variation either by connecting reactors in series or by extending a tubular reactor in the axial direction is considered. Series connexion is always superior to extension because it prevents backmixing at the points of connexion.