bluuebunny/crossref_metadata_2025 huggingface dataset:
Limited enzymic degradation of proteins: A new approach in the industrial application of hydrolases
Authors: Adler‐Nissen Jens
Published: July 2010

The industrial importance of hydrolases exceeds that of other classes of enzymes. A major application area for hydrolases is for the dissolution of biopolymers such as starch, pectin, cellulose and protein; in many cases it has been the desire to achieve as complete a solubilisation as possible. However, with food proteins, it has been demonstrated that a limited controlled hydrolysis may give rise to particularly interesting functional and organoleptic properties. The degree of hydrolysis (DH) is defined as the percentage of peptide bonds cleaved and is used as the controlling indice for the hydrolysis of food proteins. For a given enzyme‐substrate system, at least five independent indices can be defined: S (substrate concn), E/S (enzyme/substrate ratio), pH, T (temperature) and t (time). The advantage of the DH‐concept is that of these five variables, four (S, E/S, T, t) can be replaced by DH, i.e. within certain limits of S, E/S, T and t, the properties of a particular protein‐enzyme system are solely dependent on DH and pH of the hydrolysis. Empirically, this is demonstrated for soya‐protein isolate hydrolysed with Alcalase and theoretically the same result can be derived from the fact that there is substrate saturation throughout the reaction. These theoretical calculations are the basis for the so‐called θ(h)‐method, by which the significance of a particular hydrolysis indice can be studied. For each empirically derived hydrolysis curve, the hydrolysis time corresponding to any DH is found. Over a complete DH interval the proportion between the hydrolysis time for each DH is then calculated. If this term, denoted θ(h), is the same for all DH, the properties of the hydrolysates are independent of variations in the hydrolysis indice under study. A statistical procedure must be used to determine if θ(h) is constant or not. The θ(h)‐method is thus a valuable tool in the practical optimisation of industrial hydrolysis processes as the hydrolysis reaction curve under varying process conditions can be precalculated. The procedure may possibly be of interest in the hydrolysis of other biopolymers.
Use of immobilised cells with special emphasis on the formation of products formed by multistep enzyme systems and coenzymes
Authors: Mosbach Klaus
Published: July 2010

Despite the increasing number of reports in the literature on the immobilisation of cells or enzymes for the production of compounds of more complex nature involving multistep enzyme systems and coenzymes, no such systems are yet known to be used commercially on a large‐scale basis (vaccine production by microcarrier‐attached animal cells being an exception). Various systems that have been described are reviewed including plant and animal cells. Special emphasis is given to the choice to be made between the use of immobilised cells or immobilised enzyme sequences. In this context alternative regeneration methods for coenzymes are discussed. Special attention is brought to the potential for such biosyntheses with immobilised‐permeabilised cells. It is likely that the list of immobilised cells‐enzymes used at present and restricted to single enzymic steps will be extended in the not too distant future by more complex systems.
Biomethanation: Its future development and the influence of the physiology of methanogenesis
Authors: Melchior Jean‐Luc , Binot Roger , Perez Inocenta Aguilar , Naveau Henry , Nyns Edmond‐Jacques
Published: July 2010

Bioconversion of organic matter into methane by anaerobic bacteria is a process better understood each day. The technology of biomethanation takes advantage of this in a number of ways, three of them being examined in this paper.

First, when biomethanation is conducted under continuous, completely mixed conditions without active biomass recycle, a bottleneck may arise from the limited number of methanogenic bacteria present in the digestion mixed liquor. As the specific methane production rate was shown to be also limited, the resulting overall methane production must remain low. ‘Second generation’ methane digesters are being designed so as to trap the methanogenic bacteria within the digester, a fact which was demonstrated by the accumulation in the methane digestion mixed liquor of coenzyme F420.

Second, when the feedstock for biomethanation consists of insoluble organic matter, the preliminary solubilisation of this insoluble matter is often rate‐limiting. It was shown that the inverse of conversion varies linearily with the inverse of mean residence time, which allowed the calculation of ‘ultimate’ conversion. Application of this technique to the individual components of a complex feedstock, determined independently, allowed us to identify problems of rate limitation and of bacterial competency. Two‐step methane digestion systems should help to overcome this second bottleneck.

Third, monitoring of the biomethanation process needs major improvements. Even simple analytical methods such as dry organic matter or chemical oxygen demand determinations suffer major drawbacks and may lead to erroneous estimated efficiencies. A graph is proposed which attempts to correlate heats of combustion, mean oxidation stages and specific chemical oxygen demands with efficiencies with the aim of detecting anomalous values.
Animal cell technology: An overview
Authors: Spier Raymond E.
Published: July 2010

The review focuses attention on the different kinds of equipment which are used to grow large quantities of the two types of animal cells; the monolayer or surface‐dependent cell and the suspension or surface‐independent cell. The methodologies used to obtain reliable performance are described as are some examples of the application of microprocessors to monitor and control operational parameters. The kinds of products which are currently obtained from animal cells are listed and the future potential of genetically engineered animal and prokaryotic cells is discussed.
Use of microcarrier culture for the production of herpes simplex virus (type 2) in MRC‐5 cells
Authors: Griffiths Bryan , Thornton Barry
Published: July 2010

The ultimate aim of this work is the production of a subunit vaccine of herpes simplex virus (HSV). The first step was towards the development of a high‐yielding process for the production of HSV in tissue cells. The microcarrier system was evaluated for this purpose as it is a unit process with good scale‐up potential and is a monolayer‐growth method, essential for HSV production. Details are given of a closed perfusion system with environmental control which was capable of growing MRC‐5 cells to densities in excess of 105 cm−2 (3 × 106 cm−3). However, it has proved difficult, so far, to obtain good titres of HSV in this system. A novel approach to the production of HSV antigen with cell membrane‐associated antigens was tried. Preliminary trials in a guinea‐pig model indicated that these membrane‐associated antigens afforded protection against genital infection with HSV‐2.
Modern developments in mutagenesis
Authors: Saunders Gunter , Allsop Aileen , Holt Geoffrey
Published: July 2010

Mutants of Penicillium chrysogenum and Streptomyces clavuligerus have been isolated on the basis of increased sensitivity to far ultraviolet light far (u.v). In the former case the strain was also sensitive to a wide range of other mutagens, including alkylating agents and ionising radiations, but proved not to be hypermutable by any of these, whereas in S. clavuligerus two strains were hypermutable relative to their wild‐ type progenitor when treated with far u.v. In addition, various environmental conditions, including liquid holding and treatment with caffeine, isoniazid and nalidixic acid, increased mutant yield. The results obtained clearly show that induced mutation frequency can be enhanced both by mutation of genes involved in DNA repair and by modification of environmental conditions during or after mutagenic treatment. The importance of this and other modern developments in mutagenesis for the design of rational industrial strain‐improvement programmes is discussed.
Thermal crystallisation of amorphous calcium phosphate to α‐tricalcium phosphate
Authors: Kanazawa Takafumi , Umegaki Takao , Uchiyama Naoki
Published: July 2010

Dehydration and thermal change in amorphous calcium phosphate (ACP) have been studied by thermogravimetry, differential thermal analysis and X‐ray diffractometry. ACP retained water up to about 773 K. Immediately after the dehydration, a high‐temperature form of calcium phosphate, α —Ca3(PO4)2 (α ‐TCP), was obtained by ignition of ACP precipitated from the solution with a high degree of supersaturation. The kinetics of thermal crystallisation of α‐TCP from ACP were also studied.
Comparison of intermittent and continuous loading of stationary fixed‐film reactors for methane production from wastes
Authors: van den Berg L.(Bert) , Kennedy Kevin J.
Published: July 2010

Intermittent loading of a stationary fixed‐film reactor (approximately 35 dm3) with bean‐blanching or pear‐peeling waste allowed the same or higher loading rates and rates of methane production as continuous loading. Slug‐loading one‐or two‐times daily or continuous loading for 7 out of 24 h allowed loading rates of up to 26 kg Chemical Oxygen Demand (COD) day−1 m−3 and rates of methane production of up to 3.5 m3 day−1 m−3 packing void volume, the latter almost 30% higher than during continuous (24 h) loading. The efficiency of converting COD into methane decreased noticeably at high intermittent loading rates. During one‐or two‐times daily loading large amounts of hydrogen were also produced during the first 1–2 h after loading.
Chemistry and pharmacology of β‐adrenoceptor antagonists
Authors: Smith Leslie H.
Published: July 2010

The development of β‐adrenoceptor antagonists from the β‐stimulant isoprenaline is discussed. Routes of synthesis for the two series of agents that have emerged, the arylethanolamines and the aryloxypropanolamines, are outlined. The various biological screens that are used to define the pharmacological indices of the β‐adrenoceptor antagonists are described and the relevance of these is discussed. The structural requirements for a given pharmacological profile are outlined briefly and this is then related to the drugs clinically available. The clinical indications in which β‐blockers are currently used and the future directions of β‐adrenoceptor research are indicated.
Synthesis of some new oxazoloquinolines and stilbyloxazoloquinolines
Authors: Hammam A. S. , Yanni A. S. , Khalil Z. H. , Abdel‐Hafez A. A.
Published: July 2010

A new series of 2‐aryl(alkyl)oxazoloquinolines (IV) were prepared by the reaction of 7‐amino‐8‐hydroxyquinoline with aromatic (or aliphatic) aldehydes in the presence of piperidine as a catalyst. Interaction of 2‐methyloxazolo[4,5‐h]quinoIine with aromatic aldehydes in the presence of piperidine as a catalyst gave 2‐stilbyloxazolo [4,5‐h]quinolines. The structural configuration of the prepared compounds was determined by elemental and spectral analysis.
A comparison of rates of disproportionation and transalkylation of m‐xylene
Authors: Aneke L. E.
Published: July 2010

The relative rates of toluene transalkylation, disproportionation and benzene transalkylation of m‐xylene over a catalyst consisting of 72% HY zeolite, 18% β‐AlF3 and 10% (all w/w) Cu have been studied at a temperature of 723K, reciprocal space velocity of 352 g h−1 mol−1 and at total pressures varying between 101 and 911.93 kPa. The catalysed disproportionation of m‐xylene is fastest and this has been explained in terms of the greater basicity of m‐xylene over either benzene or toluene, whereas the catalyst is acidic. Thus m‐xylene would be expected to adsorb more strongly on the catalyst.
N‐alkylated‐4,5‐diamino‐1,8‐dihydroxyanthraquinones: Dyes for polyester fibres
Authors: Fisher Alan , Lee Chi‐Sun , Peters Arnold T.
Published: July 2010

The synthesis of a series of N‐mono‐and bis‐alkylated derivatives of 4,5‐diamino‐1,‐8‐dihydroxyanthraquinone is described. These compounds dye synthetic polymer fibres in blue to greenish‐blue shades of good fastness properties; bis‐alkylation results in decreased substantivity, but excellent dyes result from the use of mixtures of mono‐and bis‐alkylated derivatives.
Variation in cell‐wall strength of Klebsiella pneumoniae NCTC 418 with change in agitation speed in a chemostat system
Authors: John Wase D. A. , Nesaratnam Suresh T. , Blakebrough Norman
Published: July 2010

Klebsiella pneumoniae (NCTC 418) was grown in a chemostat with impeller speeds between 700 and 1000 rev. min−1. An inverse relationship between impeller speed and the cell‐wall strength of the organism was found and explained.
Effect of carbon‐oxygen and carbon‐sulphur surface complexes on the adsorption of mercuric chloride in aqueous solutions by activated carbons
Authors: Lopez‐Gonzalez Juan De Dios , Moreno‐Castilla Carlos , Guerrero‐Ruiz Antonio , Rodriguez‐Reinoso Francisco
Published: July 2010

Several activated carbons obtained from commercial sources have been tested for their ability to remove mercuric chloride (HgCl2) from aqueous solutions. The chemical nature of the surface of the activated carbons was changed by introducing carbon‐oxygen and carbon‐sulphur surface complexes. The influence of these types of complexes on the adsorption of HgCl2 by the activated carbons has been studied. It seems that the existence of hydroquinonic, phenolic and hydrosulphide groups on the surface of the carbon reduces Hg(II) to Hg(I). However, there was an increase in the adsorption of Hg(II) when sulphide or hydrosulphide groups were present on the surface of the carbon. The effect of the pH of the solutions on HgCl2 adsorption was also studied; when the pH was changed from 1 to 7 there was an enhancement of the adsorption of HgCl2 by the activated carbons.
Structure‐activity relations of β‐adrenergic agents
Authors: Main Brian G.
Published: July 2010

A review of the structure‐activity relations in aryloxypropanolamine β‐adrenoceptor drugs is presented. The effect of substitution in various parts of the molecule on β1/β2 selectivity and degree of partial agonism is discussed. Cardiac (β1) selectivity is achieved by hydrophilic compounds with either p‐amide substitution in the aryl ring, or a hydrogen bonding group in the amine side chain. Lipophilic compounds with branched chains tend to be β2 selective. Partial agonist activity may also be controlled by hydrogen bonding groups in the side chain and by aromatic substitution. Here 3,4‐dihydroxyl groups give full agonists, mono‐and des‐hydroxy (OH) groups partial agonists. The size of any o‐substituent is critical and a plot of Taft's steric factor versus partial agonism gives a linear relation. By manipulation of the above factors all combinations of selectivity and agonist activity may be achieved.
Electrokinetic behaviour of coal particles suspensions
Authors: Caoca José , Bueno Julio L. , Sastre Herminio
Published: July 2010

Measurements of the zeta potential of coal suspensions have been carried out by micro‐electrophoresis. The influence of colloidal particles concentration, temperature, pH and ionic strength on two types of Spanish coals have been studied. Experimental results are discussed in terms of the adsorptive properties of coal surface and with regard to the formation of aggregates by coagulation.
Studies on fermentation‐broth rheology of a penicillium strain with cellulose as substrate
Authors: Manchanda A. C. , Jogdand V. V. , Karanth N. G.
Published: July 2010

The rheological behaviour of cellulose fermentation broths of Penicillium funiculosum culture has been investigated. The shear stress‐shear rate behaviour is explained satisfactorily by a power law model, although there appear to be small yield stresses, particularly at high substrate concentrations.
Effect of the presence of a syntan on the dyeing properties of nylon 6
Authors: Guthrie John , Cook Christopher C.
Published: July 2010

The effect of treatment of undyed nylon 6 with a synthetic tanning agent, Cibatex PA (Ciba‐Geigy), on the rate of absorption of C.I. Acid Red 13 has been studied. The observed reduction in the rate of dyeing becomes more pronounced with increasing concentration of syntan present on the fibre before the coloration process. For pretreated nylon, the rate of dye uptake is at a maximum after a dyeing time which is dependent on the concentration of syntan; for untreated nylon, the maximum rate of dye uptake occurs after very low dyeing times. The belief that the syntan is initially present on the fibre as a ‘ring’ or deposit in the outer regions of the fibre is supported by the observation that hot aqueous treatments of syntanned nylon, which would be expected to increase the diffusion of the syntan into the interior of the polymer matrix, tend to greatly reduce the time at which the maximum rate of dye uptake is observed.
Hydrogenation of benzene to cyclohexene on an unsupported ruthenium catalyst: Physical and chemical characterisation of iron‐poisoned catalysts in relation to their catalytic performance
Authors: Ingemar Odenbrand C. U. , Andersson S. Lars T.
Published: July 2010

The physical and chemical characteristics of an unsupported Fe‐Ru catalyst, used in the hydrogenation of benzene to cyclohexene, has been investigated. The chemical composition was determined by X‐ray diffraction and ESCA. The catalyst consists of an Fe‐Ru alloy and hydrous iron oxides. The texture of the catalyst was determined by adsorption measurements and by microscopy. With increased iron content the BET surface area and the pore volume decreases. The decrease in surface area affects all pore‐size intervals uniformly. The surface area measured by H2 adsorption decreases more rapidly than the BET surface area. The macroscopic particle size is constant up to an iron content of 15–20%. At higher contents their size decreases rapidly. The decreased Ha coverage on the catalyst surface on addition of iron was correlated to an increased yield of the desired intermediate cyclohexene. The chemisorption of benzene is also decreased by iron and, at poisoning levels above the optimal, planar adsorption of benzene is probably sterically hindered, whereas cyclohexene adsorption is less affected. This results in a decreased yield of cyclohexene at iron contents above the optimal. Hydrogenation of benzene to cyclohexene, performed in an alkaline aqueous phase, is shown to be influenced by diffusion. The catalyst particles (6–14 μm diameter) are large enough to make the overall rate limited by pore‐diffusion processes at 390 K. The maximum yield of cyclohexene has been correlated to the calculated effectiveness factor. The influence of poisoning and mass transfer, on the process, has been separated.
Hydrogenation of ethyne catalysed by supported solutions of tris‐(triphenylphosphine)chlororhodium (I)
Authors: Gil Figueroa Jesus M. , Winterbottom John M.
Published: July 2010

The hydrogenation of ethyne and propyne, catalysed by supported solutions tris‐(triphenylphosphine) chlororhodium (I) [RhI(PPh3)3Cl] has been studied in a fixed bed reactor at 1 atmosphere total pressure over the temperature range 60–90°C. A number of silica gel supports and reaction solvents, of different co‐ordination strengths, including molten triphenylphosphine itself were examined to determine their effect on catalyst activity and selectivity. Optimum liquid loadings were observed for each support and the presence of excess triphenylphosphine was essential to the promotion and maintenance of any catalyst activity and the optimum molar ratio PPh3/RhI (PPh3)3Cl =70. The catalyst was 100% selective for ethene formation, but suffered progressive deactivation. The use of strongly co‐ordinating solvents and microporous supports gave rise to longer catalyst life, at the expense of catalyst activity. Propyne also hydrogenated with 100% selectivity to propene, but without noticeable deactivation. It is concluded that strong co‐ordination of ethene is a likely cause of catalyst deactivation, whereas propene, conversely, co‐ordinates very weakly and does not hydrogenate. The best catalyst activity is achieved with a combination of a macroporous support and a weakly co‐ordinating solvent, but in this situation the catalyst is most easily poisoned when ethyne is hydrogenated.
Adsorption of copper nitrate from solution on silica gel
Authors: Choudhary Vasant R. , Vaidya Subhash H.
Published: July 2010

Adsorption of copper nitrate from aqueous solution on to silica gel at different concentrations and temperatures has been investigated. Effect of precalcination temperature of silica gel and that of pH of the solution on the adsorption have also been studied. The adsorption was due to ion exchange and followed the Freundlich isotherm.
Catalytic decarbonylation of furfural in a fixed‐bed reactor
Authors: Coca Jose , Morrondo Eduardo S. , Sastre Herminio
Published: July 2010

The oxidative decarbonylation of furfural was studied in a fixed‐bed reactor. Mixtures of Mn, Zn, Cd, Sr and K oxides supported on spherical and cylindrical alumina were used as catalysts. In this paper the effect of the temperature and feed flow on the reaction yield for the catalysts tested and hence optimum reaction conditions are reported. Catalysts employed in this work are compared with Pd‐catalysts, frequently used for the decarbonylation of furfural.
Ethanol production by immobilised yeast and its CO2 gas effects in a packed bed reactor
Authors: Cho Gyu Hoen , Choi Cha Yong , Choi Yang Do , Han Moon H.
Published: July 2010

Immobilised yeast trapped in an alginate matrix demonstrated maximum activity at 30°C and showed no pH effect between 3 and 7. Substrate inhibition was observed at glucose concentrations above 8% but the immobilised cells retained 70% of their maximum activity at 20% glucose concentration. The operational stability of immobilised cells was lower in simple glucose solution than in the activation medium in which only 20% of the activity was lost after 10 days operation. Inactivated immobilised yeast beads were reactivated by incubation in activation medium without a significant increase in cell numbers in a bead. During the operation of the immobilised yeast in a packed bed reactor, CO2 gas accumulation adversely affected the reactor performance. An ideal plug flow reactor, not taking into account the formation of CO2 gas bubbles and the presence of mass transfer resistance, was simulated using a kinetic model for the production of ethanol and the simulation results were compared with the actual reactor performance to determine the CO2 gas effect, quantitatively. Up to 45 % of the substrate conversion was lost due to the accumulation of CO2 gas bubbles in all cases.
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

A 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

Ni 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

Flyash, 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

The 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

Phase 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

Equations 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

An 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

Contacting 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

The 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

The 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

The 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

The 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

A 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

From 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

Any 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

The 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

Change 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

The 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

A 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

The 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

Permeation 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

A 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

Ternary 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.
The role of liquid ion exchange in the processing of complex solutions
Authors: Agarwal Jagdish C. , Klumpar Ivan V.
Published: July 2010

The use of liquid ion exchange in the processing of complex solutions is described, with particular reference to the development and economics of the process for co‐extraction and selective stripping of copper and nickel.
Experience with a pilot‐scale electro‐organic synthesis process
Authors: King Christopher J. H.
Published: July 2010

A 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.
Growth rate dependence of enzyme synthesis in chemostat cultures: α‐amylase, β‐galactosidase, acid phosphatase and β‐fructosidase
Authors: Toda Kiyoshi , Takeuchi Toshihiko , Sano Haruhiko
Published: July 2010

Specific rate of enzyme synthesis in microbial cells was correlated to specific growth rate in chemostat culture using three strains of microorganism. α‐Amylase production by Bacillus subtilis was linearly associated with growth rate in a glucose‐limited chemostat culture. β‐Galactosidase production by Saccharomyces fragilis was rather invariable with growth rate in a galactose medium. β‐Fructosidase production by Saccharomyces carlsbergensis in a phosphate‐poor glucose medium was independent on growth rate, except at low dilution rates where it increased with growth rate. Production of acid phosphatase by the same microbe showed a maximum at a particular intermediate dilution rate. These relationships were summarised with an equation of induction—repression model. Comparison of the chemostat results with those of batch fermentation provided some enhancement factors of a continuous fermentation: 1.23–9.82 regarding enzyme productivity and 0.53–2.88 regarding enzyme concentration. The production of β‐fructosidase was much improved among the enzymes tested when continuous culture methods were used.
The electroforming of iron foil
Authors: Lai Stephen H. F. , McGeough Joseph A.
Published: July 2010

A process for the high‐speed electroforming of iron foil is described. The electrolyte can be operated over a current density range of 10–100 A dm−2. The quality of the electroformed iron foil is dependent upon process variables, and in terms of its main mechanical, electrical and magnetic properties, is comparable with that of many conventionally‐produced metal foils.