bluuebunny/crossref_metadata_2025 huggingface dataset:
Excess Gibbs free energy and excess enthalpy for mixtures of benzene and 1,1,2‐trichlorotrifluoroethane
Authors: Armitage David A. , Linford Roger G. , Thornhill David G. T.
Published: July 2010

The rapid measurement of static vapour pressures of binary liquid mixtures as a function of composition by a new continuous‐dilution apparatus is described. These measurements, together with the computed excess Gibbs free energies, are reported for mixtures of benzene and 1,1,2‐trichlorotrifluoroethane at 283.30, 287.83, 293.21, 298.21, 303.06 and 308.15 K over the full composition range, and are compared with the results of Linford and Hildebrand. The excess enthalpies were measured directly at 303.15 K using a batch calorimeter. The equimolar excess enthalpy is + 754 J mol−1, which is close to the value, + 727 J mol−1, calculated from the temperature dependence of the computed equimolar excess Gibbs free energies.
Degradative addition reactions in relation to protein‐bound cystine
Authors: Asquith R. S. , Otterburn M. S. , Yeung K. W.
Published: July 2010

A study has been made of the degradation of protein‐bound cystine, in various proteins, when degraded by alkali in the presence of aliphatic amines. This shows that the structure of amine has a significant effect on the rate of degradation of the cystine. The products of degradation of cystine which resulted from the intermediate, dehydroalanine, have been determined quantitatively at different temperatures of treatment. Attempts are made to correlate the amounts of products with the nature of the amines used and the hydrophobicity of the proteins.
Factors affecting the preparation of supported nickel—Molybdenum hydrodesulphurisation catalysts
Authors: Laine Jorge , Pratt Kerry C. , Trimm David L.
Published: July 2010

Studies have been carried out of the optimisation of the preparation of supported nickel molybdate used to catalyse the hydrodesulphurisation of thiophene. It was found to be advantageous to impregnate alumina with nickel before molybdenum and the most active catalyst was formed from nickel acetate. Optimal activity was obtained by calcining the catalyst at 773K, increasing the temperature of the reactor to this value as slowly as possible. Presulphiding at 673K in pure hydrogen sulphide was also advantageous. These observations are discussed in terms of the inorganic chemistry of the catalysts.
Studies on ferrocene and its derivatives. V. Preparation of some new ferrocenyl pyrazolines, pentan‐1,5‐diones and β‐ketosulphides
Authors: Hassan Khairy M. , Aly Morsi M. , El‐Naggar Galal M.
Published: July 2010

Ferrocenyl pyrazolines have been prepared by the reaction of ferrocenyl chalcones with diazomethane and/or substituted benzenesulphonyl hydrazides. A Michael reaction on ferrocenyl chalcones using phenyl benzyl ketone and/or thiophenol yielded the corresponding ferrocenyl pentan‐1,5‐diones and ferrocenyl‐β‐ketosulphides, respectively.
Kinetics of carbon monoxide oxidation over chromium sesquioxide with two reaction paths
Authors: Kobayashi Masayoshi
Published: July 2010

Kinetics of CO oxidation over chromium sesquioxide with two reaction paths I and II was studied in detail in the temperature range of 378–445 K (105–172°C). The rate constants in each elementary step were estimated as a function of temperature by using transient response and steady‐state data without the help of a parameter optimisation technique. A comparison of their values showed that the rate of path I is limited by surface reaction, and the rate of path II is controlled by three steps: surface reaction; desorption of CO2; and adsorption of O2, which is the slowest step over the entire temperature range studied. Good agreement of the simulated response with the experimental response due to the linear temperature rise proved the validity of the mechanism and the kinetic analysis. The selectivity of reaction path I was also discussed.
The stability of lactic acid production in resting suspensions of Lactobacillus delbrueckii
Authors: Rees John F. , Pirt S. John
Published: July 2010

The stability of resting glycolytic activity (RGA) i.e. lactic acid production from glucose, in non‐growing suspensions of Lactobacillus delbrueckii was examined. Non‐growing conditions were imposed by removal of essential nutrients or by the addition of antibiotics. The stability of RGA was reduced in fast‐grown chemostat cells. Mg2+, reducing agents, the rigorous exclusion of oxygen and a constant supply of energy source gave a five‐fold increase in RGA and a 25‐fold increase in stability in cells deprived of a nitrogen source. Glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) activity severely limited RGA after about 8 h of incubation. No evidence of excessive ATP accumulation or ADP depletion was found. Addition of chloramphenicol, actinomycin D or mitomycin C decreased RGA stability over a 24‐h period. Addition of yeast extract and tryptone to a mixture containing phosphate, Mg2+, thioglycollate and chloramphenicol gave a three‐fold increase in RGA which lasted for about 1 h. Mg2+ is believed to stimulate the glycolytic sequence directly and oxygen probably inhibits GAPDH by interaction with the ‐SH groups of the enzyme. Tryptone and yeast extract probably stimulate pyruvate kinase activity, and this enzyme is also absolutely dependent on fructose‐1, 6‐diphosphate for activity.
Corrosion inhibition by sodium molybdate
Authors: Armour Alan W. , Robitaille Dennis R.
Published: July 2010

The ability of sodium molybdate to inhibit corrosion of mild steel is demonstrated using laboratory and field test data. Initial evidence is also presented indicating that molybdate inhibits the corrosion of copper and aluminium. Environmental aspects including fish toxicity data are discussed as is the likely mechanism of molybdate inhibition.
Hardened alite pastes of various porosities II. Morphology and microstructure
Authors: Abo‐El‐Enein Salah A. , Mikhail Raouf Sh.
Published: July 2010

The hardened alite pastes were prepared by using initial water:alite ratios of 0.20, 0.30, 0.45 and 0.60. The microstructures of the low and high porosity pastes were investigated by scanning electron microscopy. The results obtained indicated that the cementing system is really a composite material having a structure controlled by the total pore system of the hardened paste. In low porosity pastes, the hydration products are semi‐crystalline; whereas in high porosity pastes, the hydration products possess a massive tabular structure.
Thermal and related studies of some zirconia gels
Authors: Gimblett Gareth , Rahman A. Atiqur , Sing Kenneth S. W.
Published: July 2010

The thermal properties of a number of zirconia gels, prepared with various precipitants, have been studied by thermogravimetry, differential thermal analysis and evolved gas analysis. The results obtained show that ligands derived from the various precipitants are incorporated in these gels and strongly influence their high temperature behaviour. The observed properties are interpreted on the basis of a defect structure involving O2‐ vacancies generated through the removal of these ligands at higher temperatures.
Some engineering aspects of high pressure water electrolysers
Authors: Stickland Richard J. R.
Published: July 2010

The high pressure electrolyser was developed specifically for the UK Ministry of Defence for use on Royal Navy nuclear submarines to produce oxygen for life support. Consequently more attention was paid to safety and reliability than to the cost of production. The development of the electrolytic cell, the subsequent development and engineering required to incorporate the cell into a system which enabled the cell to operate satisfactorily and which controlled the process, rendering it safe in the event of any anticipated failure, is described here. Aspects covered include material selection, the interaction between electrolyte flow and gas purities, prevention of gas mixing, features associated with working at high pressures and automation.
The effect of cell design on the selectivity of organosyntheses
Authors: Tomov Nenand R. , Jansson Robert E. W.
Published: July 2010

Two typical reactions of commercial interest have been performed in a number of different cells. The selectivity of the overall reaction and the distribution of coproducts are shown to be sensitive to the mixing conditions within a cell, even for reactions under essentially chemical control.
Mechanism of retention of hydrocarbons in reservoir rocks. Role of polar compounds and effect of additives
Authors: De Savignac Alain , Dupin Patrice , Matondo Hubert , Bories Serge , Lattes Armand
Published: July 2010

Evidence is given for the involvement of hydrophobic interactions in the retention of hydrocarbons in oil fields. A prerequisite is that the surface of the reservoir rock has to be hydrophobic. This was obtained through adsorption of lipophilic polar compounds. The isotherms for the adsorption of dodecylamine hydrochloride and N‐hexadecylpyridine hydrochloride were plotted. The treated quartz could take up large amounts of toluene. The relationships between some features of the isotherms and the retention phenomenon have been analysed. The effect of water‐structuring additives (e.g. LiF, CaCl2, NaF and guanidine hydrochloride) on the recovery of hydrocarbons was investigated by means of static and dynamic methods.
Microbial degradation of synthetic polymers
Authors: Pirt S. John
Published: July 2010

Successful processes for the microbial degradation of synthetic polymers began to emerge in 1978. Organisms capable of biodegradation of polyurethane polyester, polyethylene, polyethyleneglycol, polystyrene, polyvinylalcohol, polyacrylonitrile, nylon 3 and nylon 6 were identified. There was a maximum molecular weight for attack and in some cases only oligomers were susceptible. The polymers were converted to biomass or smaller molecules or polymers without certain side groups. The degradation processes should be capable of much improvement by accelerated evolution of the microbial agents in continuous cultures. Co‐oxidation of the polymers with another substrate, for example methane, with methane‐oxidising bacteria as agents is suggested as a possible degradative means. The insolubility of polymers is a serious barrier to microbial attack and constitutes a major problem for investigation. Ultimately bio‐degradation should provide a mild means for the recycling of synthetic polymers with the advantage of greater control over the degree of degradation.
The effect of mixing on the paired dimerisations of methyl acrylate and diethyl malonate
Authors: Johnson David K. , Jansson Robert E. W.
Published: July 2010

The paired dimerisations of methyl acrylate and diethyl malonate have been carried out in a pump cell, a capillary gap cell, a parallel plate cell and a trickle tower cell, and the distributions of products related to the environments in the cells. It is clear that good dispersion of malonate anions is essential for high selectivity, but that too high a dispersion rate leads to loss of current efficiency through the parasitic iodine cycle.
Investigation of factors in the optimisation of penicillin production
Authors: Calam Christopher T. , Ismail Basil A.‐K.
Published: July 2010

Penicillin production trials were carried out in stirred 5‐dm3 fermenters to collect data and investigate aspects of the process likely to be important in on‐line optimisation. These included the calculation of growth from the production of carbon dioxide, the relation between age and productivity and the effect of dilution and culture replacement. Three types of media were used, a synthetic medium and complex commercial‐type nutrient media based on corn‐steep liquor or peanut meal together with a nutrient feed and pH control. All gave good results although the synthetic medium tended to show only transient production on some occasions. An equation was devised enabling the correct calculation of the growth curve from carbon dioxide output. It was found that the maintenance energy requirements (as indicated by CO2 production) were much higher with synthetic medium than with complex media. Decay curves (of Qpen vs time) were readily calculated using Shu's17 equation. The highest outputs of penicillin were obtained by dilution or replacement systems, but it was essential to start the process early when the penicillin‐producing enzymes were active and stable. It was also necessary to supply glucose at an adequate rate, to hold dissolved oxygen concentration above 25% and avoid too high cell concentrations. It was concluded that theories of penicillin production based on feed‐rate or dilution, or on the effect of age, are essentially complementary, both aspects being important in determining the optimal course of the fermentation.
Conversion of abienol into tetrahydroepimanool by anaerobic processes in woodroom debarking effluent
Authors: McKague A. B. , Lee E. G‐H.
Published: July 2010

The conversion of abienol into tetrahydroepimanool by anaerobic processes in woodroom debarking effluent is demonstrated. This conversion is used as a preparative method for tetrahydroepimanool.
Metal support interactions in the palladium‐catalysed decomposition of furfural to furan
Authors: Singh Harendra , Prasad Murari , Srivastava Rameshwar D.
Published: July 2010

The catalysed decarbonylation of furfural to furan by palladium‐carbon and pallidium‐alumina has been examined. The results reveal a combination of support effects which are possibly related to a direct electronic support function whereby furfural and hydrogen can be adsorbed on support surfaces with subsequent surface migration to metal sites for reaction.
Experimental problems in the application of the marker‐pulse technique
Authors: Overstall John , Jansson Robert E. W.
Published: July 2010

In principle the marker‐pulse technique provides a simple way of characterising the hydrodynamic regime in electrochemical reactors. However, in practice, a number of experimental difficulties are encountered. These arise from the nature and placement of the electrodes, and from undesired electrical coupling of the marker and detector instrumentation. Methods for minimising these problems and improving experimental data are described.
A mechanistic model for penicillin production
Authors: Bajpai R. K. , Reuß M.
Published: July 2010

A mechanistic model for the production of penicillin has been investigated. Contois kinetics of growth coupled with a substrate‐inhibition model for product formation has been used to predict data for batch‐fed fermentation on synthetic and corn steep liquor medium. With the incorporation of oxygen limitation on growth and product formation it has been possible to investigate the effects of feeding rate, initial sugar concentration and the volumetric mass transfer coefficient for oxygen (KLa). Various experimentally observed trends for penicillin fermentation have been predicted qualitatively. Different product formation models have been critically reviewed with respect to the production of secondary metabolites.
Synthesis of some new azopyrazole dyes
Authors: Fahmy Sherif Mahmoud , Badran Abdel Hakim , Elnagdi Mohamed Hilmy
Published: July 2010

A variety of new azopyrazolo [1,5‐c]‐as‐triazine dyes have been synthesised via diazotisation of 3‐amino‐4‐arylazo‐1‐pyrazolin‐5‐one and coupling with active hydrogen reagents. These dyed nylon 6, nylon 66, acrylic, polyester, silk and wool with colours ranging from scarlet red to dark brown and may find useful applications.
Studies of the trimethylsilyl derivatives of unhydrated cement and hydrated cement pastes by fourier transform infrared spectroscopy
Authors: Sarkar Asok K. , Roy Della M.
Published: July 2010

Trimethylsilyl derivatives (T‐derivatives) of unhydrated cement and hydrated cement pastes were studied by Fourier transform infrared spectroscopy. The infrared spectra of all these derivatives are very similar. However, when the spectrum of the T‐derivatives of the unhydrated cement is subtracted from those of the hydrated pastes, a difference in the characteristics of the siloxane bands is observed in the subtracted spectra. The implications of these observed changes to cement hydration process is discussed.
Effect of addition of poly‐N‐vinylpyrrolidone on the surface characteristics of zirconia gel
Authors: El‐Akkad Taghreed M.
Published: July 2010

The surface characteristics of pure and poly‐N‐vinylpyrrolidone‐containing zirconia gel were investigated by nitrogen adsorption at — 196°C. Structural and phase changes were studied by X‐ray diffractometry and differential thermal analysis. The inclusion of poly‐N‐vinlypyrrolidone did not retard the appearance of the X‐ray diffraction patterns of zirconia gel but only led to a decrease in their relative intensities. Surface characteristics were greatly affected by inclusion of the polymer in the gel, as evidenced by a remarkable increase in surface area, total pore volume and pore radii. The optimum increase was observed for the sample containing 5% of poly‐N‐vinylpyrrolidone. On thermal treatment at 300°C the pure sample exhibited an increase in the micropore volume which can be attributed to perforation of the gel during the evolution of a considerable amount of hydrated water. On the other hand, the inclusion of poly‐N‐vinylpyrrolidone led to a strengthening of the skeletal wall of the gel to withstand perforation. However, thermal treatment at 550°C led to a marked decrease in the surface area, especially for samples containing high percentage of poly‐N‐vinylpyrrolidone, e.g. 10%. This decrease may be attributed to shrinkage of the polymer at higher tempature which led to the disappearance of a great fraction of the area.
Effect of hydrogen sulphide on the deactivation of alumina‐supported ruthenium methanation catalysts
Authors: El‐Sawi Mahmoud , Forzatti Pio , Pasquon Italo , Villa Pier L.
Published: July 2010

The deactivation of a 0.5% ruthenium‐alumina catalyst for the methanation reaction has been studied at 250 and 400 °C in the absence and presence of small concentrations of hydrogen sulphide (H2S). The adequacy of a suggested mechanistic model for the methanation reaction has been confirmed and the model has been applied to the deactivation in the absence of H2S, which is significantly improved with respect to an empirical methanation rate equation. The effect of the presence of 10 mg dm−3 H2S in the reactant stream on the catalyst deactivation rate has also been investigated.
Dimensional stability of glass‐ionomer cements
Authors: Hornsby Peter R.
Published: July 2010

Factors influencing the shrinkage behaviour of glass‐ionomer cements are described, with particular reference to the effects of cement age and the binding of water contained in the matrix. Dimensional changes occurring in cements exposed to alternating dry and saturated conditions are shown to be irreversible and a linear relationship is depicted between shrinkage and volume fraction of matrix. A failure mechanism involving matrix shrinkage is proposed to explain mechanical property changes which are evident when cements are maintained in environments of low relative humidity.
The thermal degradation of zinc O,O‐dialkyl phosphorodithioates and related compounds in petroleum media. Part 1. Zinc O,O‐diisobutyl phosphorodithioate
Authors: Ellis Raymond J. , Lake Peter J. , Marshall Roger A. G.
Published: July 2010

The thermal decomposition of zinc O,O‐dialkyl phosphorodithioates is acknowledged to play a significant part in their activity as multipurpose lubricating oil additives. Therefore, the isobutyl derivative in pentadecane solution has been degraded in a novel apparatus under a nitrogen atmosphere. The principal volatile products were found by gas‐liquid chromatography and mass spectrometry to be O,O,S‐triisobutyl phosphorodithioate, isobutanethiol and isobutene. In addition to these volatile products a solid (insoluble in organic solvents) was formed. This contained virtually all the zinc in the original reactant and had a zinc: phosphorus ratio of 2:3. It also contained carbon, hydrogen, sulphur and oxygen but the proportions of the latter two elements were unreliable. Variation of the period of heating, the temperature from 176 to 240°C and the concentration of the reactant from 1.4 to 7.0 × 10−2M affected the relative proportion but not the nature of the products formed. An equation involving the reaction of two molecules of the reactant has been written but kinetic data is required in order to establish a mechanism.
Hydrolysis of friedel—crafts reaction products at different temperatures
Authors: Barnes D. Ian , Robinson J. Gordon , Marr George
Published: July 2010

Toluene was reacted with propionaldehyde in the presence of aluminium chloride and the yields of the different products obtained were found to be dependent on the end temperature at which the hydrolysis was carried out. Most of the compounds identified in the reaction product were obtained in lowest yield when the hydrolysis was carried out at 87°C.
A problem in the production of defluorinated phosphate
Authors: Deutsch Yoetz , Sarig Sara
Published: July 2010

In Israel the phosphate industry produces amongst other products, defluorinated phosphate. The rock is heated to more than 1400°C with additions of phosphoric acid, soda ash, silica and steam. Occasionally not all the fluorine volatilises from the phosphate rock. It was proved statistically that the volatilisation of fluorine was incomplete whenever the concentration of zinc in the product (and presumably therefore the raw material) was relatively high. Experiments in the laboratory simulating the industrial process confirmed this.
Properties of hydroxyapatite prepared by the hydrolysis of tricalcium phosphate
Authors: Monma Hideki , Ueno Seiichi , Kanazawa Takafumi
Published: July 2010

Non‐stoichiometric hydroxyapatite was prepared by the hydrolysis of α‐tricalcium phosphate. The apatite was obtained as a powder and hardened with and without stirring during the hydrolysis. The apatite had a general formula, characteristic dehydration and pyrolysis behaviour similar to that of precipitated non‐stoichiometric hydroxyapatite. In addition, it exhibited some new phenomena (i.e. thermal reaction between lattice H2O and PO43− above 473 K, formation of ESR centres above 473 K and disappearance at 873–973 K, and a slight weight loss at 873–973 K). Apatite particles were composed of aggregates of cylindrical rods or thin blades grown along the c‐axis or {100} faces of apatite structure. Hardened apatite materials with various porosities above 55% and bulk densities below 1.4 g cm−3 were obtained by using different water‐soluble additives. The strength of the hardened materials was 20–500 kg cm−2 in compression and 10–120 kg cm−2 in bending. The strengths were improved at least two to three times by impregnating the hardened materials with methyl methacrylate polymer.
Preparation of gelatinous aluminium hydroxide from aqueous solutions of organic aluminium salts by reaction with alkali
Authors: Sato Taicho , Suzuki Misao , Ikoma Shuji
Published: July 2010

The preparation of gelatinous aluminium hydroxide from aqueous solutions of the formate, citrate or tartrate of aluminium on addition of aqueous sodium hydroxide has been investigated under different conditions. The precipitates from aqueous solutions of aluminium formate consist of amorphous aluminium hydroxide, pseudoboehmite, bayerite, hydrargillite or their mixtures, depending on the condition of preparation. A mixed solution of aluminium citrate and sodium hydroxide yields no solid‐phase product without aging on heating to enhance the hydrolysis of aluminium citrate. The resulting precipitate exists as pseudoboehmite, independent of the preparation conditions. In contrast, aluminium tartrate is not hydrolysed to precipitate aluminium hydroxide even by aging on heating.
Sorption in porous crystals: Equilibria and their interpretation
Authors: Barrer Richard M.
Published: July 2010

In porous rigid zeolite crystals intracrystalline pore volumes are sub‐divided into regular channels and cavities of molecular dimensions only, and the total pore volumes can be determined. A consequence is that both absolute and Gibbs excess sorptions can be measured, examples of which have been considered. The Clapeyron‐Clausius equation is derived using solution thermodynamics so that isosteric heats should strictly be derived from absolute sorption isotherms. Consequences of using the equation to give corresponding heats for Gibbs excess sorption isotherms are considered, and the two heats compared for several systems. With the minimum assumption that mean hydrostatic stress intensity and mean concentration of intracrystalline sorbate can be related by a virial equation, the corresponding virial sorption isotherm correlates sorption measurements and gives equilibrium constants and thermodynamic data, which have been exemplified for particular systems. Model isotherms can also have limited applicability and can give information at a molecular level. Model isotherms in the presence of interaction between adjacent pairs of guest molecules have been considered with particular reference to the behaviour of binary mixtures.
Interactions between an alga and three bacterial species in a consortium selected for photosynthetic biomass and starch production
Authors: Lee Yuan‐Kun , Pirt S. John
Published: July 2010

A four‐membered consortium (MA003) of an algal species and bacteria was selected from a natural source for its ability to grow at 37°C and produce starch photosynthetically from carbon dioxide. The photosynthetic culture consisted of a Chlorella‐like green alga (A003) and three heterotrophic bacteria, Alcaligenes sp. (B001), Flavobacter sp. (B002) and Serratia sp. (B003). The substrates for the bacterial growth were probably organic nitrogen and carbon compounds excreted by the alga at specific rates which were independent of the algal specific growth rate. The maximum specific growth rate of the alga was decreased by an inhibitor produced by bacterium B002. Bacterium B001 removed the inhibitor of algal growth released by bacterium B002, and bacterium B003 decreased the growth of bacterium B002 and consequently the production of algal growth inhibitor. The growth of bacterium B003 was greatly suppressed in the four‐member consortium MA003. The coexisting bacteria in toto, did not affect the growth rate, yield and starch production of the algal member, but did help to establish a stable ecosystem and increase the biomass available. A culture density up to 36 g dry weight dm−3 was achieved without significant variation in the ratio of the species in the culture.
Antibiotics from the newly isolated Streptomyces elizabethii. II. Isolation and characterisation of the antibiotics
Authors: Bird Clive W. , Latif Muhammad
Published: July 2010

The principal antibiotics formed by Streptomyces elizabethii have been isolated and identified as actinomycins IV and V, together with a methylpentaene macrolide, elizabethin, stereoisomeric with previously reported compounds.
The technological importance of the crystallographic and surface properties of copper phthalocyanine pigments
Authors: Fryer John R. , McKay Robert B. , Mather Robert R. , Sing Kenneth S. W.
Published: July 2010

New and previously reported results are combined to emphasise the importance of fundamental crystallographic and surface chemical properties on the technology of copper phthalocyanine pigments. Particular attention is paid to undesirable aggregation of pigment crystals and to the changes in aggregate structure and crystal phase which occur during ageing. The two most commercially significant forms of copper phthalocyanine are the α‐ and β‐polymorphs. The crystals of both consist of parallel molecular stacks. In β‐phase crystals, the coordinate bonding between adjacent molecules within the stacks promotes crystal growth in the direction of the stacks, producing commonly observed rod‐shaped crystals. Moreover, the molecular stacks of the β‐phase, being interlocked, are not readily distorted. In contrast, the distortion of lattice planes in the α‐phase can accommodate mismatch between contiguous crystals, and promote their fusion into strongly coherent aggregates. Although the strength of aggregation is thus influenced by the crystal lattice, the geometric structure of aggregates is largely determined by crystal shape, brick‐shaped crystals being more prone to aggregation than rod‐shaped crystals. Aggregates of brick‐shaped crystals are porous, and solvent molecules can penetrate some way into their internal structure. Ageing may then occur. Changes in crystal phase and aggregate structure are discussed at some length. New evidence is presented for the existence of an intermediate metastable state in the α‐→β‐phase transformation induced by solvents. The β‐→α‐phase change induced by mechanical grinding is shown to start at the surface of β‐phase crystals, and then to extend gradually throughout their bulk. Examples are given of different kinds of ageing of aggregate structures. Ageing of aggregates of α‐phase crystals in liquid toluene involves not only Ostwald ripening and a transformation to the β‐phase, but also crystal fusion (as occurs during ageing in toluene vapour). In liquid n‐propanol, on the other hand, the aggregates are converted to highly consolidated structures.
Nickel extraction by 2‐hydroxy‐5‐tert‐butylbenzaldehyde oxime
Authors: Stepniak‐Biniakiewicz Danuta , Szymanowski Jan
Published: July 2010

Nickel extraction from aqueous solutions between pH 3 and 10 using 2‐hydroxy‐5‐t‐butylbenzaldehyde oxime was investigated. Iso‐octane, octane, xylene and dichloro‐ethane were used as diluents. It was found that nickel extraction is dependent upon the equilibrium pH, the mol ratio of oxime : nickel and the nature of the diluent. The composition of the nickel‐oxime complex is in the ratio of 1:2. Extraction data, infrared spectra and cryoscopic measurements have shown the association of the oxime in the organic phase and the solvation of the nickel complex by the oxime molecules. The degree of solvation was found to be higher in dichloroethane than in octane.
Adsorption of metal cations on wool carbonising waste. Part 2. Adsorption mechanisms
Authors: Perineau Francis , Farag Karim , Gaset Antoine , Constant Georges
Published: July 2010

In order to elucidate the mechanisms of adsorption of Hg2+, Ag2+, Ni2+, Cr3+, Al3+, Zn2+ and Pb2+ on wool carbonising waste, the possible role of the various ionisable groups (‐SH, ‐SO3H, ‐OSO3H, ‐COOH and ‐NH2) of the substrate has been considered together with the corresponding solubility products and dissociation constants of the metal salts thus formed.
A Survey of Methods for the Preparation of Colloidal Dispersions of Ferric‐hydroxy Polycations
Authors: Segal David L.
Published: July 2010

Methods for the preparation of ferric‐hydroxy polycations have been surveyed because of their possible importance in aqueous corrosion processes. The choice of the preparative route is dependent on the desired concentration, purity and volume of the polycation dispersion.
Adsorption of alcohols from aqueous solution by ZSM‐5
Authors: Milestone Neil B. , Bibby David M.
Published: July 2010

Isotherms have been measured for the adsorption from aqueous solution of water soluble alcohols onto the zeolite ZSM‐5. For methanol and ethanol the amount of alcohol adsorbed increases with increasing percentage of Al2O3, whereas for n‐butanol the amount adsorbed decreases as the amount of Al2O3 increases. Adsorption of alcohols is also dependent on the cation form. For the alkali metal ion forms, the amount of alcohol adsorbed decreases as the ionic size increases, the effect being particularly pronounced for Cs+. Subsequent alcohol desorption was studied by thermogravimetry and mass spectrometry which showed that the zeolite retained a portion of the alcohol to temperatures (ca 250°C) sufficiently high that catalytic breakdown occurred. This reduces its likely potential for commercial alcohol concentration.
Fundamental aspects of the extraction and stripping of palladium by LIX 65N
Authors: Hoh Ying‐Chu , Chuang Wen‐Shou , Yueh Peng‐Shiung
Published: July 2010

The fundamental aspects of the extraction and stripping of palladium from its chloride solution by LIX 65N diluted with Kermac 470B have been studied. Equilibria of extraction and stripping, temperature effect, the variation of sodium thiosulphate concentration on stripping and rate of extraction and stripping on the system Pd2+‐LIX 65N‐Kermac 470B are reported.

The fundamental aspects of the extraction and stripping of palladium from its chloride solution by LIX 65N diluted with Kermac 470B have been studied. Equilibria of extraction and stripping, temperature effect, the variation of sodium thiosulphate concentration on stripping and rate of extraction and stripping on the system Pd2+‐LIX 65N‐Kermac 470B are reported.
Studies on the decomposition of α‐primary hydroperoxide of secondary butyltoluene in alkaline medium
Authors: Kulsrestha Girendra N. , Shanker Uma , Sharma Jaipal S.
Published: July 2010

α‐Primary hydroperoxides of s‐butyltoluene (SBT) are preferentially decomposed when the hydroperoxide concentrate is treated with 2 M aqueous sodium hydroxide at 70°C. The decomposition is complete in 1 h. The rate of decomposition and the nature of products formed suggest the reaction to be first order with respect to the primary‐hydroperoxide concentration in accord with the Kornblum‐De La Mare mechanism. Salt formation of the hydroperoxide precedes the decomposition.
Transalkylation of toluene with C9 aromatic hydrocarbons over ZSM5 zeolites
Authors: Meshram Namdeo R. , Kulkarni Suneeta B. , Ratnasamy Paul
Published: July 2010

The transalkylation reactions of a mixture of toluene and C9+ aromatics were studied over HZSM5 catalysts of varying SiO2:Al2O3 ratios (30–800) as well as over a NiHZSM5 catalyst. As the SiO2: Al2O3 ratio is increased, the rate of transalkylation is decreased. Among the C9 aromatics that were present in the feed, the ethyl toluenes were extensively de‐ethylated to toluene. The shape‐selective characteristics of the ZSM5 zeolite were revealed through the relative order of reactivity of the three trimethyl benzene isomers 1.2.4>1.2.3>1.3.5. The stable life of the catalyst can be prolonged by the incorporation of nickel. The influences of process parameters such as temperature, pressure, space velocity and H2: hydrocarbon ratio are also presented. It was observed that the transalkylation of C9 aromatics with toluene to yield xylenes occurs mainly on the external surface of the ZSM5 crystals. The disproportionation of toluene to yield benzene and xylene, however, takes place predominantly in the pore system.
Kinetic studies on the catalytic reduction of o‐, m‐, and p‐nitrophenols by hydrazine
Authors: Goswami N. , Rahman M. L. , Huque M. E. , Qaisuddin M.
Published: July 2010

The kinetics of the reduction of o, m‐ and p‐nitrophenols by hydrazine over Raney nickel catalysts have been studied spectrophotometrically. The reactions have been found to be first order with respect to both hydrazine and nitrocompound. The first order behaviour has been observed at the initial part of each of the reactions. The influences of solvent, salt and the amount of catalyst on the reaction rate have been investigated. The rate constants have been found to depend on the nature of the substrate, the dielectric constant, the ionic strength and the amount of catalyst. The activation energies for the reactions in various solvent compositions have been determined and their variations interpreted in favour of an ionic mechanism. The effect of the p‐substituent on the activation energy has been explained in terms of the electron‐shifting capacity of the substituent.
Some substituted polysaccharides as low temperature middle distillate additives
Authors: Abou Naga H. H. El , Abd Azim W. M. El , Mahmoud M.
Published: July 2010

Substituted polysaccharides with different molecular weights (mol. wt 12 000–15 500) were synthesised by reacting aliphatic acid chlorides with different carbon numbers (C12‐C18) with dextrin. The resulting polymers were purified and tested as pour point depressants and flow improvers for middle distillates (gas oils). Comparative evaluation of these polysaccharides with some commercial additives showed their good activity, especially as flow improvers.
The determination of hydrophilic lipophilic balance values for some hydroxyoximes and their correlation with rates of copper extraction
Authors: Szymanowski Jan , Cox Michael , Hirons Christopher G.
Published: July 2010

Hydrophilic lipophilic balance (HLB) values provide a measure of the surface activity of organic molecules, and thus may be helpful in the screening of potential metal extractants. Data are presented which correlate the water solubility and rate of copper extraction with the HLB values for a series of hydroxyoximes. The results show a decreasing water solubility and rate of copper extraction as the HLB value decreases, that is, as the reagent becomes more lipophilic. As an estimate of the HLB value can be made from the molecular structure it is possible that some predictions can be made of extraction behaviour.
Comparative kinetic study of ethylbenzene isomerisation on acidic and non‐acidic Pt/Al2O3 catalysts
Authors: Susu Alfred A. , Ako Churchill T.
Published: July 2010

Ethylbenzene (EB) isomerisation to o‐, m‐ and p‐xylene was investigated in a microcatalytic reactor on acidic and non‐acidic Pt/Al2O3 catalysts. Total conversion and product yield distribution data were determined on both catalysts for EB and the xylenes in the temperature range 513–673 K and 1.8 atm. Total conversion of each of the C8 isomers went through a maximum as the temperature was increased. The onset of reaction occurred at a lower temperature, and the initial rates were higher on the acidic catalyst. Furthermore, the acidic catalyst was found to be very selective in the production of p‐xylene at temperatures less than 563 K, and of p‐ and o‐xylene at temperatures less between 563 and 593 K. The Wei‐Prater method was used for the calculation of absolute rate constants for EB isomerisation on both catalysts. Generally, the rate constants were higher on acidic Pt/Al2O3.
Removal of Cr(V1) from aqueous solutions by adsorption on fly ash‐wollastonite
Authors: Panday K. K. , Prasad Gur , Singh V. N.
Published: July 2010

The ability of a homogeneous mixture of fly ash and wollastonite (1:1) to remove Cr(V1) from aqueous solutions by adsorption has been investigated. The extent of removal is dependent on concentration, pH and temperature of the solution. The applicability of the Langmuir isotherm for the present system has been tested and the surface mass transfer coefficient at 30°C and pH 2.0 determined. Maximum removal was observed at pH 2.0 and 30°C. The adsorption is first governed by diffusion followed by surface compound formation. The thermodynamic parameters, desorption results and infrared studies indicated that the surface compounds, formed by interaction of adsorbate ions and different constituents of mixed adsorbent, were stable in nature.
Oxidation of cyclohexanone to adipic acid with a cobalt acetate/oxygen/acetic acid system
Authors: Rae Dubasi Govardhana , Raghunathan T. S.
Published: July 2010

The liquid phase oxidation of cyclohexanone to adipic acid at 378 K using oxygen as the oxidising agent and cobalt acetate as the catalyst in an acetic acid medium was investigated both at atmospheric pressure and at a pressure of 0.5MN m−2. The effects of catalyst concentration, solvent concentration and partial pressure of oxygen, were studied at a constant stirrer speed of 535 rev min−1. Increasing the solvent concentration and decreasing the catalyst concentration (up to 0.113×10−3 kmol m−3) had positive effects on the overall first order reaction rate constant. It was also found to vary linearly with gas flow rate.
Effects of precipitation temperature on the powder properties of Mg(OH)2 and calcined MgO
Authors: Copperthwaite M. , Brett N. H.
Published: July 2010

Mg(OH)2 has been precipitated from MgCl2 solution with CaO at temperatures in the range 0–55°C and with a final pH of 11.7. The hydroxides, and the oxides derived from them by calcination under standard conditions, have been characterised by settling rate, chemical analysis, tap density, X‐ray crystallite size, B.E.T. surface area, electron microscopy and green and fired density of isostatically pressed pellets. Increasing the precipitation temperature affects these parameters in different ways and attempts have been made to correlate these changes.
Determination of the heat change in solvent extraction of metals. The extraction of zinc (II) from hydrochloric acid solutions by high molecular weight amines in various organic solvents
Authors: Sato Taichi , Nakamura Takato , Kuwahara Masami
Published: July 2010

The heat change associated with the uptake of zinc (II) has been examined by using a twin type isoperibol calorimeter in the extraction of zinc (II) from hydrochloric acid solutions by trioctylamine hydrochloride (TOAHCl) and trioctylmethyl‐ammonium chloride (TOMAC) in various organic solvents such as benzene, chlorobenzene, o‐dichlorobenzene, toluene, m‐xylene, nitrobenzene, carbon tetrachloride and 1, 2‐dichloroethane. It was found that the dependence of apparent molar heat change (the value of the heat change detected with regard to the concentration of zinc (II) reacted) on the aqueous chloride concentration could be attributed to the change in the distribution of zinc (II) chloride species in the aqueous phase. Taking account of this fact, variable Y, which constitutes the sum of the change in enthalpies for the relevant steps in the extraction of zinc (II), except the transformation of ZnClj(2‐j)+ to ZnCl42‐, in the aqueous phase, is introduced. From the values of Y obtained, it is concluded that in the extraction by TOMAC, Y correlates with the solubility parameter of diluent, suggesting that the organic phases may be regarded as regular solutions, while in the extraction by TOAHCl, no clear‐cut relation holds between Y and the physico‐chemical constants of the diluent such as dipole moment, dielectric constant and solubility parameters.
Equilibrium studies on adsorption of basic dyes on hardwood
Authors: Asfour H. M. , Fadali O. A. , Nassar M. M. , El‐Geundi M. S.
Published: July 2010

Equilibrium conditions of adsorption of a basic dye on hardwood sawdust were studied using the Langmuir and Freundlich isotherms. Two sets of experiments were carried out at different particle sizes and temperatures. The adsorption of the basic dye on hardwood was found to conform with the two isotherms. The capacity of hardwood for the adsorption of basic dye was found to increase by decreasing the particle size and increasing the temperature. The cost of hardwood adsorbent is only 8.4% that of activated carbon.
Colour removal from textile effluents using hardwood sawdust as an absorbent
Authors: Asfour H. M. , Nassar M. M. , Fadali O. A. , El‐Geundi M. S.
Published: July 2010

Decolourisation of a dilute solution of a basic dyestuff was carried out by using hardwood sawdust as adsorbent. At 80°C 85% decolourisation occurred within 100 min at an initial concentration (Co) of 200 mg dm−3. There was a 44% reduction in contact time when the temperature was raised from 25 to 80°C. The rate parameter for different initial dye concentrations was found to follow the equation: kco=4.20Co0.88 and the rate parameter for different mean diameter dm followed the equation kdm=4.1 (l/dm)0.135. The activation energy of the process was 9.83 kJ mol−1 which shows that the rate controlling step is intraparticle diffusion.
Factors affecting the solubility of gypsum: II. Effect of sodium hydroxide under various conditions
Authors: Ghorab Hanaa Y. , Fetouh Safaa H. Abou El
Published: July 2010

A quantitative estimation of the effect of sodium hydroxide on the solubility of gypsum in the presence of lime at 30, 60 and 100°C is given. At 30°C the solubility of gypsum was promoted by a 0.0146M solution of sodium hydroxide which at a concentration as low as 0.0029M raised the sulphate ion concentration at 60 and 100°C. At the three temperatures studied the solubility curves of gypsum first rose slowly then more rapidly around 0.02 to 0.08M NaOH. In the range 0.08 to 1M NaOH solution, a constant value of the sulphate ion concentration was measured which corresponded to the complete dissolution of gypsum, even in the presence of lime. The solubility curve of gypsum was lowered slightly at 30°C in a supersaturated lime solution and was depressed by concentrations lower than or equal to 0.02M NaOH solutions at 60 and 100°C.
Recommended flowsheets for the electrolytic extraction of lead and zinc from red sea polymetal ore
Authors: Madkour Loutfy H.
Published: July 2010

The polymetal complex ore Umm‐Gheig considered in Egypt as a rather rich source of lead and zinc is subjected to mineralogical, chemical, spectral, X‐ray and differential thermal analyses. Hydrometallurgical treatments based on leaching, precipitation and electrodeposition of metal from the ore are established. The influences of current density, temperature and metal ion concentration on the Faradic current efficiency are discussed. Advantages and disadvantages of flowsheets and various approaches depending on convenient baths for the electro‐deposition of metals are investigated. The results of electron microscopic investigation confirmed by metal value data given in the A.S.T.M. cards coincide well with those given by chemical analysis.
Organic matter and sulphur distribution in phosphorites: Relevance to phosphate processing
Authors: Mair A. Donald
Published: July 2010

Organic matter from North Carolina and Idaho phosphorites has been extracted and characterised using humic acid, kerogen and bitumen fractions. Extracts from thermally treated rock showed that the organic matter from the two source rocks responds quite differently to the heat treatment. With current commercial calcination of both North Carolina and Idaho phosphate rock at about 800°C, problems with acid‐evolvable sulphide formation have arisen. From the findings made on the thermal behaviour of the organic matter and the associated sulphur redistribution, alternative processing strategies have been suggested for both North Carolina and Idaho phosphorites. Since these two rocks represent extremes in maturity for the contained organic matter, the results should be of relevance to other organic‐rich unweathered and low‐grade phosphorite or phosphatic shale deposits.
Cation exchange in clays and mudrocks by methylene blue
Authors: Taylor Roy K.
Published: July 2010

The nature of methylene blue (hydrochloride) adsorption is reviewed because the dye has recently been adopted for determining the presence of clay in quarry aggregates. Although it is demonstrated that methylene blue is not an ideal exchange reagent, details are given for overcoming most of the shortcomings, with particular reference to the aggregates test. It is demonstrated that methylene blue commonly underestimates the cation exchange capacity (CEC) of untreated expandable smectites. In contrast, it provides a fair reflection of the change in ratio of 7 Å/10 Å clay minerals in British mudrocks and overconsolidated clays. Plasticity indices of the latter show a high level of positive correlation with measured CEC.
Selective transformation of benzyl chloride into benzyl thiocyanate in the presence of ion‐exchange resins. Generalisation of the reaction
Authors: Catusse Chantal , Catusse Robert , Gharbi Rachid El , Gaset Antoine
Published: July 2010

The use of ion‐exchange resins as a support for thiocyanate ions made it possible to transform benzylic or aliphatic halides into thiocyanates both in high yield and with remarkable selectivity. A study of the effects of various physicochemical parameters governing the behaviour of the ion exchanger allowed the most favourable reaction conditions to be determined. The best transformation rates were obtained using a macroporous resin, appropriately hydrated, in a non water‐miscible solvent.