bluuebunny/crossref_metadata_2025 huggingface dataset:
Esterification of phthalic anhydride with 2‐ethylhexanol
Authors: Bhutada S. R. , Pangarkar V. G.
Published: July 2010

The kinetics of esterification of phthalic anhydride with 2‐ethylhexanol has been studied using the following catalysts‐tetrabutyl titanate (TBT), tetrabutyl zirconate (TBZ) and paratoluene sulphonic acid (PTSA). In each case the kinetic parameters (rate constant, order with respect to various reactants and catalyst, activation energy, collision frequency) have been determined. The titanates and zirconates have been found to be better than the conventionally used acidic catalysts to produce di‐2‐ethylhexyl phthalate.
Flotation of metal hydroxide precipitates. I. Flotation of copper hydroxide
Authors: Basak Sergiusz , Charewicz Witold A.
Published: July 2010

Flotation of copper hydroxide precipitate has been investigated at total initial copper concentration 10−2M with sodium dodecylbenzenesulphonate (DBSNa) and dodecyldimethylbenzylammonium bromide (DDMBABr), both at initial concentration 10−4M. In particular, granulometric analysis of the precipitate and measurement of its electrokinetic potential were carried out over a wide range of the acidity of aqueous precipitate suspension in order to establish essential factors governing flotation of the precipitate. Moreover, adsorption of the flotation collectors by the precipitate as well as the rate of precipitate sedimentation were measured. The cationic collector (DDMBABr) neither influenced the electrokinetic potential of copper hydroxide precipitate nor adsorbed on its surface. Consequently, no flotation of copper hydroxide was observed with (DDMBABr). On the other hand, the anionic collector (DBSNa) influenced the electrokinetic potential of copper hydroxide within the same pH range where adsorption of DBSNa on the precipitate was observed and flotation was effective. The rate of flotation varied with the pH of the aqueous suspension. This dependence was irregular and presumably governed by the aggregation of precipitate grains since the rate of flotation increased with the size of the aggregates.
Extraction of copper from dilute solutions by LIX 64N. Effect of dekalin and tetralin as diluents on the equilibrium and rate of mass transfer
Authors: Pazos Carmen , Ma Díaz Ramona , Coca José
Published: July 2010

Liquid‐liquid equilibrium data and mass transfer rates for the extraction of copper from dilute aqueous sulphate solutions by LIX 64N with dekalin (decahydronaphthalene) and tetralin (1,2,3,4‐tetrahydronaphthalene) as diluents are reported. The stripping of copper from the organic phase was also studied. For an initial copper concentration of 1.5 g dm−3 extraction efficiency decreases as the concentration of tetralin increases in the diluent mixtures of dekalin‐tetralin. This behaviour is explained as a result of the formation of oxime aggregates and the interaction between the oxime and the diluent. Initial rates of extraction and stripping were determined by the single drop technique. The linear relation between initial rates of extraction and the difference of interfacial tension between the extractant in the diluent and the diluent itself holds for the system under investigation.
Effect of the degree of crosslinking on the selectivity of ion‐exchange resins
Authors: Jackson Mervyn B. , Pilkington Norman H.
Published: July 2010

Most of the literature states that increasing the degree of crosslinking of an ion‐exchange resin increases the selectivity of the resin for the preferred ion. Further examination of the data for ions where complex formation is insignificant suggests that such generalisations are frequently invalid. The effect of the degree of crosslinking on the selectivity for divalent over univalent ions is trivial over the range of crosslinking from 1 to 16% divinylbenzene in cation exchange resins based on sulphonated polystyrene. Similar behaviour holds for anion exchange systems.
Studies on oxidative dehydrogenation of n‐butane on bismuth molybdate‐aluminium phosphate catalysts. I. Catalyst characterisation
Authors: Shenoy Subhash C. , Rao Musti S.
Published: July 2010

The aim of the present investigation has been to develop a suitable catalyst for the oxidative dehydrogenation of n‐butane to butenes and 1,3‐butadiene. Preliminary experiments showed that molybdic oxide‐aluminium phosphate catalysts were effective for the dehydrogenation of n‐butane. In order to improve the activity of the molybdic oxide‐aluminium phosphate catalyst, bismuth was introduced in the catalyst, and the catalyst activity was investigated further. Three types of bismuth molybdates, Bi2O3.MoO3 (γ‐phase), Bi2O3.2MoO3 (β‐phase), and Bi2O3.3MoO3 (β‐phase), were chosen to vary the Bi/Mo ratio in the catalysts. The catalysts, in turn, were characterised using X‐ray diffraction, infrared, and differential thermal analyses. These studies revealed that both Bi2O3.MoO3 and Bi2O3.2MoO3, containing corner‐shared Mo‐O octahedra, are suitable catalysts for the oxidative dehydrogenation of n‐butane.
Interactions of CO and NO with the perovskite‐type oxide larho3
Authors: Tascón Juan M. C. , Olga Oliván A. M. , Tejuca Luis G.
Published: July 2010

Some aspects of the interactions of CO and NO with LaRhO3 have been studied. The reduction of this oxide with CO occurs where the contracting sphere model is of perovskite structure stable up to a concentration of anion vacancies of ca. 2e− per molecule. By reduction of LaRhO3 at 817 K, rhodium was obtained, highly dispersed on a matrix of La2O3. After a reduction‐oxidation cycle at 871 K the particle size of the perovskite decreased drastically. The activation energy of the reduction (67 kJ mol−1) was significantly lower than that of other LaMO3 oxides of group‐VIII metals. Coverages of CO(θCO) and NO(θNO) at room temperature were lower than 3%, θNO being substantially higher than θCO. The reversibly adsorbed fractions of CO and NO underwent a remarkable decrease after preadsorbing NO and CO, respectively. This competitive adsorption is assumed to be associated with the adsorption of CO and NO on metallic sites. NO preadsorption inhibited the total adsorption of CO more severely than the reverse, indicating that NO is bound more strongly than CO to the LaRhO3 surface.
Chemical aspects of nuclear fuel fabrication processes
Authors: Naylor Arthur , Ellis John F. , Watson Ronald H.
Published: July 2010

Processes used by British Nuclear Fuels plc for the conversion of uranium ore concentrates to uranium metal and uranium hexafluoride, are reviewed. Means of converting the latter compound, after enrichment, to sintered UO2 fuel bodies are also described. An overview is given of the associated chemical engineering technology.
Thermal treatment of phlogopite and muscovite with calcium and magnesium compounds
Authors: Aitta Eero , Leskelä Markku , Lajunen Lauri H. J. , Jyrkäs Kauko , Seppälä Erkki
Published: July 2010

The solid state reaction between mica (phlogopite, muscovite) and calcium or magnesium sulphates or chlorides has been studied at elevated temperatures. The aim of the work was to obtain potassium in a soluble form by exchanging it by alkaline earth metal in mica. The addition of CaO, CaCO3 or MgCO3 promoted the recovery of potassium. When phlogopite, gypsum and calcium oxide were fired at 1100°C for 30 min, almost 90% of the potassium could be obtained in solution. The recoveries obtained with muscovite were significantly lower than those with phlogopite. The greatest amounts of soluble potassium were obtained by exchanging K+ ions with Ca2+ ions using CaCl2. In separate experiments with different muscovites and experimental conditions, 34–69% of the potassium content reacted to give a soluble form. The effect of the experimental conditions (reaction time, temperature, particle sizes, amount of accelerator) on the exchange reaction have been investigated.
Adsorption of thiosemicarbazide on copper cathodes
Authors: Abdel‐Wahaab Saad M. , Gomma Gamal K.
Published: July 2010

The adsorption of thiosemicarbazide (TSC) on cathodically polarised copper is studied. The adsorption follows the Flory‐Huggins and the Bockris‐Swinkels isotherms with a standard free energy of adsorption of about 20kJmol−1. Four water molecules are displaced by each adsorbing TSC molecule. This is explained on the basis of molecular models.
A comparison of treatment methods for palm oil mill effluent (POME) wastes
Authors: Edewor J. O.
Published: July 2010

A study of the operational variables involved in the treatment of palm oil mill effluent (POME) was carried out. These included the acidic or alkaline nature of the POME discharged from the oil mills, the efficiency of the decay (or digestion) of the chemical oxygen demand (COD) contents of the POME, the economic benefits that could arise from the digested sludge and biogas and finally the net economic recovery abilities of the various treatment methods available. The chemical oxygen demand (COD) contents of the POME must be reduced to an acceptable level of 2000–3000 mg solids dm−3 of sludge before the latter can be used as a fertiliser material. In 10 days of operational periods various anaerobic digestion treatment methods gave COD reduction efficiencies of 76–96%, the batch pond anaerobic digestion mode gave an efficiency of 76.5%, the continuous pond modes 92.5–95.5% and the tank digester 93.8%. In all anaerobic operations the optimal pH values of the POME media were in the range 7.1–7.6 and a ratio of the volatile acids to the total alkalinity of the media (VA/TA) of 0.3 or less was found to enhance the performance of these digesters. Economic analyses carried out on all modes of treatment gave the following economic recovery abilities: the decanter/drier system gave a break‐even situation of 3 years, the tank digester system, 2 years, and the single stage anaerobic pond system, 6 years. The batch pond system appeared not to give a break‐even situation. Of the treatment methods examined the decanter/drier and tank digester systems were concluded to be optimal.
Synthesis of 2 and 6‐triazolylthiazolo[4,5‐b]quinoxaline derivatives and their application as fluorescent disperse dyes
Authors: Phadke Ravindra Chintaman , Rangnekar Dinesh Wamanrao
Published: July 2010

Synthesis of 2‐triazolylthiazolo[4,5‐b]quinoxaline derivatives was achieved by diazotisation of 2‐aminothiazolo[4,5‐b]quinoxaline and its 6‐nitro derivative using orthophosphoric acid and sodium nitrite with a trace of nitric acid, coupling with suitable aromatic amines and subsequent cyclisation of the resulting ortho amino azo compounds. Diazotisation of 2,6‐diaminothiazolo[4,5‐b]quinoxaline with concentrated hydrochloric acid and sodium nitrite and subsequent coupling and cyclisation resulted in the 6‐triazolylthiazolo[4,5‐b]quinoxaline derivatives. These compounds were applied on polyester as fluorescent disperse dyes.
Partial hydrogenation of benzene with ruthenium catalysts prepared by a chemical mixing procedure: Preparation and properties of the catalysts
Authors: Niwa Shu‐Ichi , Mizukami Fujio , Isoyama Shigemi , Tsuchiya Tohru , Shimizu Kazuo , Imai Sumi , Imamura Juichi
Published: July 2010

Ruthenium catalysts were prepared in different alcohols by a chemical mixing technique, characterised by the preparation of a homogeneous solution containing catalyst components, and the uniform coagulation of the solution through hydrolysis. The technique has the potential for controlling the surface area of the catalysts and for making them porous. The ruthenium catalysts were much more effective for the partial hydrogenation of benzene to cyclohexene (maximum cyclohexene yield, 31.4%) in the absence of any poison such as alkali metal hydroxide or transitional metal sulphate in the reaction solution.
The recovery of uranium and the lanthanides from phosphate rock
Authors: Habashi Fathi , Awadalla Farouk T. , Zailaf Mohamed
Published: July 2010

A process is proposed for the treatment of phosphate rock for the recovery of uranium and lanthanides. The process assures the production of phosphatic fertilisers without polluting the environment with radioactive material.
Extraction of copper from aqueous solutions with carboxylic acids
Authors: María Díaz Ramona , Fernández Ana María , Xiberta Jorge
Published: July 2010

The distribution equilibrium data at 25°C for the extraction of copper from aqueous solutions, containing sodium nitrate or sodium sulphate, by carboxylic acids using toluene, benzene and carbon tetrachloride as diluents have been measured. The carboxylic acids used are n‐myristic, n‐lauric and n‐capric. The results obtained led to the conclusion that the composition of the extracted species corresponds to (CuR2.HR)2, being irrespective of both the nature of organic phase and the aqueous phase. The addition of sodium sulphate, instead of sodium nitrate, decreases the extraction efficiency due to the formation a CuSO4 ion‐pair into the aqueous phase. The diluent effect has been related to the activity of the dimerised carboxylic acid in the diluent.
Removal and recovery of uranium by polyvinyl polyacrylate
Authors: Nakajima Akira , Sakaguchi Takashi
Published: July 2010

Various polymer esters were screened to determine which adsorb uranium the best. Polyvinyl polyacrylate adsorbed uranium extremely well and its behaviour was investigated in detail. Polyvinyl polyacrylate can selectively accumulate uranium from a solution containing various heavy metals. The uptake of uranium is very rapid and is markedly affected by pH, but not by the co‐existence of the carbonate ion. As it can adsorb uranium in the pH region 4 to 7, it can be used to remove and recover uranium from uranium refining waste water. It can recover uranium almost completely from solution at pH 6 and almost all uranium adsorbed is desorbed easily with 0.1 M HCl. Thus, polyvinyl polyacrylate can be used repeatedly in adsorption‐desorption process.
Corrosion of tin in aqueous solutions of mono‐, Di‐ and trichloroacetic acids
Authors: Abdel‐Wahaab S. M. , Abo‐El Wafa O. , Kamel G. E. , Rashwan S. M.
Published: July 2010

The corrosion behaviour of tin in stagnant mono‐, di‐ and trichloroacetic acids solutions in the pH range 1–6 and at concentrations 4.0 to 5 × 10−4 M was investigated. The results indicate behaviour that is generally the same but there is some dependence on the acid concentration and the pH value. In 4.0 to 10−2 M solutions, the corrosion rate (W) increased with increasing acid concentration and decreasing pH value from 1 to 4 as follows: log W=a+b log C, where b=0.70, 0.42 and 0.35 for tri‐, di‐ and mono‐chloroacetic acids respectively. At high concentrations 4.0 to 10−2 M and in the pH range 1–6, the steady state corrosion potential shifted in the negative direction with increase of acid concentration accompanied by an increase in the corrosion rate, indicating that the corrosion process becomes anodically controlled by the complexing of Sn2+ ions with organic acid anions and that the order of aggressiveness is mono‐<di‐<trichloroacetic acids. In dilute solutions (10−2 to 5.10−4 M) in the pH range 1–6 the steady state potential shifted in the noble direction with increase of acid concentration (accompanied by a remarkable decrease in the corrosion rate). Corrosion inhibition in dilute solutions was attributed to film formation on the surface of tin which may result from the hydrolysis of tin species.
Hydrolysis of sugar cane bagasse with hydrochloric acid, promoted by metallic cations
Authors: Schuchardt Ulf , Duarte Humberto C.
Published: July 2010

Lithium chloride, in combination with commercial grade hydrochloric acid, is very effective in the hydrolysis of prehydrolysed sugar cane bagasse. After 10 min at 50°C the holocellulosic portion is completely dissolved and after 20 min most of the sugar oligomers are hydrolysed to monomers, making the time‐and energy‐consuming post‐hydrolysis unnecessary. With longer reaction times the sugars start to reoligomerise and decompose. Zinc chloride is a milder promoter, requiring post‐hydrolysis even after reaction for 30 min at 50°C. On the other hand, it does not decompose the sugars giving the highest sugar yields after prolonged reaction time and post‐hydrolysis. Ferric chloride is mostly ineffective in the hydrolysis of cellulose but is a good promoter of the hydrolysis of the sugar oligomers, under the reaction conditions.
A comparative study of a fluidised bed reactor and a gas lift loop reactor for the IBE process: Part I. Reactor design and scale down approach
Authors: Schoutens Gerda H. , Guit Ruud P. , Zieleman Gerard J. , Luyben Karel Ch. A. M. , Kossen Nico W. F.
Published: July 2010

For the continuous production of isopropanol‐butanol mixtures by immobilised Clostridium spp. (the IBE process) two reactor types were studied: a fluidised bed reactor with liquid recycling (FBR) and an external loop gas lift reactor (GLR). A large scale design (50–65 m3) was made for both reactors. A regime analysis, by evaluating the time constants for e.g. mixing and conversion, identified the ruling regime. Via the scale down approach two representative model reactors were developed: a 10 dm3 FBR reactor (H/D=25, D=0.08 m) and a 15 dm3 external loop GLR (H/D = 12.5, Dr=Dd=0.08 m). For both reactors the hydrodynamical behaviour and the total reactor performance were studied and are described in parts II and III of this study.
Automated affinity separation processes
Authors: Chase H. A.
Published: July 2010

This paper describes the automation of fixed‐bed affinity separation techniques for the purification of proteins. The basic requirements of an automated system suitable for carrying out such a separation are detailed together with an introduction to the concept of process optimisation by interactive control. Such systems can continue to optimise separations when operating conditions are variable but require that methods for the on‐line analysis of separation performance are available. Such methods require that the levels of particular proteins in the presence of other proteins can be determined and include continuous measurement of enzyme activity and the use of the new technique of rapid chromatographic analysis. The latter technique, which can also be used more generally in the process control of protein purification, is described and its use illustrated.
The use of near infrared reflectance spectroscopy in the control of flour protein content
Authors: Osborne B. G.
Published: July 2010

Near infrared reflectance spectroscopy (NIR) is a rapid (50s) and non‐destructive method of analysis of a wide variety of solid, semi‐solid and liquid samples. Since no sample preparation is required for many sample types, particularly powders, NIR is an ideal technique for process control. The use of NIR to monitor the protein content of flour in order to optimise the milling conditions and the composition of the grist is described. Control of the blending of flours or supplementation with wheat gluten to achieve a composite flour of a given protein content is proposed.
Quality control of proteins produced by recombinant DNA technology
Authors: Brewer Stepen J.
Published: July 2010

Proteins produced by recombinant DNA technology will be contaminated with residues from the organism used to express the protein, from its culture medium and from the downstream processing steps. In addition, heterogeneous proteins with incorrect sequence and/or folding may also arise. Urogastrone, a human protein, has been produced by rDNA technology in Escherichia coli and is used to illustrate methods for controlling production and downstream processing steps. Protein chemical, chemical, and biochemical methods for the characterization of the purified drug substance are then described.
Applications of recombinant DNA technology to diagnostics
Authors: Goldfarb P.
Published: July 2010

The use of recombinant DNA as a routine diagnostic tool is now a reality. Although gene probes have been available to academic researchers for a number of years, only recently has progress in recombinant DNA technology made it possible to extend their use to the screening of large numbers of samples, and make such analytical procedures part of the normal workload of hospital, analytical and commercial laboratories. It is now possible to detect genetic diseases in patients or at risk populations, and to diagnose infectious disease or identify infectious agents present as environmental contaminants. The technology can also be extended to the unambiguous identification of individuals for forensic, paternity or immigration purposes. The application of recombinant DNA technology is therefore of interest to scientists from a wide variety of disciplines.
Dimerised ethyl cyanoacetate in heterocyclic dye synthesis: New pyridine azodyes and tetrazole dyes
Authors: Fahmy Sherif M. , Mohareb Rafat M. , Abd‐All Fatma A.
Published: July 2010

A variety of polyfunctional pyridine azodyes and tetrazole dyes were prepared starting from ethyl cyanoacetate dimer. These derivatives were found to dye cellulose acetate, Nylon 6, Nylon 66, silk and wool with colours ranging from canary yellow to light violet.
A comparative study of a fluidised bed reactor and a gas lift loop reactor for the IBE process. Part II: Hydrodynamics and reactor modelling
Authors: Schoutens Gerda H. , Guit Ruud P. , Zieleman Gerard J. , Luyben Karel Ch. A. M. , Kossen Nico W. F.
Published: July 2010

A fluidised bed reactor with liquid recycle (FBR) and an external loop gas lift reactor (GLR) were designed for the production of isopropanol—butanol mixtures by immobilised Clostridium spp. and scaled down to laboratory scale (part I). Hydrodynamic models were set up for the two laboratory scale reactors. Liquid mixing in the 10 dm3 FBR was described by 10 tanks in series. Fluidisation velocities, bed expansions and axial dispersion coefficients agreed well with literature data. Liquid mixing in the 15 dm3 GLR was described by 100 tanks in series. The gas hold‐up and circulation velocity were found to decrease with increasing hold‐up of solids, in accordance with literature indications. No influence of the hold‐up of solids on the axial dispersion coefficient was determined. An integrated reactor model was set up for both reactors, using the hydrodynamic and kinetic model. Actual fermentation data are presented and compared with model predictions in part III of this study; this part will also include a comparison of reactor performances and scale up aspects.
Synthesis by enzymatic catalysis. III. Copolymerisation of amino acids and dipeptides using papain
Authors: Selvi Christine , Baboulene Michel , Speziale Vincent , Lattes Armand
Published: July 2010

After studying the oligomerisation reaction of L‐tyrosine, we investigated polymerisation of a mixture of methionine and tyrosine, which also led to the formation of a polypeptide. Various substrate concentrations and substrate/enzyme ratios were investigated. A hexapeptide was isolated containing three tyrosine and three methionine residues. Extension of the method to enzymatic polymerisation of dipeptide esters was also examined. After optimisation of the reaction, we obtained a peptide made up of four monomers using methyl L‐leucyl‐L‐tyrosinate as substrate. The results are discussed in the light of a possible reaction mechanism.
Galvanostatic and temperature kinetic studies of acid corrosion of low carbon steel in sulphuric acid in presence of malonate hydrazide
Authors: Abd el Wahaab Saad M. , Gomma Gamal K. , El‐Barradie Hussny Y.
Published: July 2010

The inhibitive effect of malonate hydrazide on the corrosion of low carbon steel (0.05% C) in 1 M sulphuric acid at different temperatures was investigated. The corrosion potential, corrosion current, and corrosion rate, as well as heat of adsorption and effective energies were calculated from the Evan's curves at different temperatures.
A process control system for the fractional precipitation of human plasma proteins
Authors: Foster Peter R. , Dickson Alan J. , Stenhouse Alexander , Walker Ewan P.
Published: July 2010

Precipitation is the principal technique used by the blood plasma fractionation industry for the separation and concentration of human proteins for clinical use. Although precipitation has many attractions it is particularly difficult to control and the resultant overshoot of key parameters is responsible for loss of product yield and sometimes quality. Much of this problem is due to the inefficiency of mixing and heat transfer in large bulk volumes of protein solution; hence control is limited by the process design. Therefore we have applied the concept of continuous‐flow processing to scale‐down process volumes, to improve the efficiency of mixing and heat transfer and to allow the opportunity for in‐line monitoring and control of important parameters. Ten years experience with a routine manufacturing process of this type has illustrated the benefits of this approach and has led to the modernisation of the process with replacement of centralised computer control by a microprocessor‐based system.
Intrinsic kinetic constants of an immobilised glucose‐isomerase
Authors: Benaiges M. D. , Solà C. , De Mas C.
Published: July 2010

The isomerization of glucose into fructose using a commercial immobilised glucose‐isomerase has been studied and an initial transitory state of the enzyme, probably due to an establishment of stationary concentration profiles, was observed. Operational conditions to minimise the effects of external and internal mass transfer were determined using immobilised enzyme particles with diameters less than 0.064 mm. Thermal enzyme deactivation of the enzyme was insignificant if it was pre‐treated with cobalt. The intrinsic kinetic constants of the reversible reaction Michaelis—Menten equation were calculated, in operational conditions free of mass transfer effects.
Biomass for energy—a review
Authors: Boyles D. T.
Published: July 2010

The enthusiasm, in recent years, for biologically derived fuels has not been repaid by the emergence of major new industries. Where they have been adopted, biofuels have needed extensive subsidies or other community support. This review examines the inherent problems of the bioenergy concept, which may ensure that biofuels will never enjoy more than a purely local exploitation. These problems derive from the relatively small usable biomass resource, its high cost and the cost of upgrading biomass to usable fuels, the unfavourable energy balance in converting high entropy feedstocks to low entropy fuels, and the anticipated effects of such processes on the environment.
Hydration of calcium sulphate hemihydrate in the presence of phosphoric acid and calcium oxide: III. Phosphogypsum
Authors: Beretka Julius , Brown Trevor
Published: July 2010

The kinetics of hydration and physical properties of plaster slurries and cast gypsums of three calcined industrial phosphogypsums containing 0.09, 0.38 and 0.73% ‘soluble’ P2O5, respectively, were investigated. The materials were neutralised with lime as in industry, and the lime addition was expressed in terms of CaO/P2O5 wt ratio from 0 to 5. It was found that the presence of 0.09% P2O5 had relatively little effect on the kinetics of hydration and physical properties of calcined phosphogypsum. However, with the material containing 0.38% P2O5 the rate of hydration of the slurry was severely retarded within the CaO/P2O5 wt ratio range of 1 to 2; the setting time increased, the strength was reduced, and all the other physical properties of the slurries and cast gypsums were greatly affected. Similar findings were observed with the material containing 0.73% P2O5, except that these changes took place within the higher and broader weight ratio range of 1.5 to 3.5 CaO/P2O5. The practical implications of these findings on the industrial conversion of phosphogypsums to good quality plaster of Paris and cast gypsum are discussed.
Mixing and mass transfer in concentric‐tube airlift fermenters: Newtonian and non‐newtonian media
Authors: Kawase Yoshinori , Moo‐Young Murray
Published: July 2010

The mixing and mass transfer characteristics in concentric‐tube airlift gas‐liquid contactors intended for possible use as fermenters are discussed. Liquid velocities, circulation times, gas hold‐ups, and volumetric mass transfer coefficients were measured in water and aqueous carboxy methyl cellulose solutions. Measurements were made in an inverted conical‐bottom device with draft tubes of three different diameters. An increase of liquid velocities at the column axis and a corresponding decrease of volumetric mass transfer coefficients due to the introduction of draft tubes were found for water as the liquid medium. For the non‐Newtonian fluids, a complicating influence of the draft tubes on liquid velocity and mass transfer, which is attributed to a combination of factors related to improvement of liquid circulation and reduction of apparent viscosity, was observed.
Effects of nutrients on α‐amyiase production and plasmid stability in fed‐batch culture of recombinant bacteria
Authors: Iijima Shinji , Kai Kenichi , Mizutani Satoru , Kobayashi Takeshi
Published: July 2010

Escherichia coli harbouring a recombinant plasmid containing the α‐amylase gene (HB101/pHI301) and its derivative which can stably maintain the plasmid (HB101/pHI301A) were cultivated in a mini‐jar fermenter. By controlling dissolved oxygen (DO) at a concentration of 2–3 μg/l and supplementing with suitable amounts of nutrients, the organisms could grow to a concentration (up to 40 g dry cell l−1) in a semi‐synthetic casamino acid medium. During culture the plasmid was maintained stably in both strains. In a synthetic medium, both micro‐organisms grew less well and plasmid‐free segregants were observed with HB101/pHI301 during the fed‐batch culture. On the other hand, plasmid pHI301A was stably maintained throughout the fed‐batch culture of HB101/pHI301A. Growth inhibitors, which may be metabolic products, accumulated in the medium and reduced bacterial growth.
Laboratory simulation of municipal solid waste fermentation with leachate recycle
Authors: Mata‐Alvarez Joan , Martinez‐Viturtia Angel
Published: July 2010

Municipal solid waste fermentation, simulating landfill conditions, was studied using five test cells operated at different temperatures. The digestion was carried out under enhanced conditions. Leachate recycle was set up in all the test cells. Depending on temperature, the digestion was complete (more than 90% biodegradable matter converted) in a period of 25 to 57 days. Optimum operating temperatures were in the range of 34 to 38°C. Two kinetic models were fitted to experimental data. Their kinetic constants were related to temperature using an Arrhenius expression. Landfill life operated under the studied conditions could be reduced to less than 2 years.
Flotation of metal hydroxide precipitates. II. Flotation of zinc and cobalt hydroxides
Authors: Basak Sergiusz , Charewicz Witold A.
Published: July 2010

Flotation of zinc and cobalt hydroxide precipitates was investigated at total initial metal concentrations of 1 × 10−2 M with sodium dodecylbenzenesulphonate (DBSNa) and dodecyldimethylbenzylammonium bromide (DDMBABr), both at initial concentrations of 1 × 10−4 M. In particular, the granulometric analysis of precipitates and measurements of their electrokinetic potential were carried out over a wide range of acidity of aqueous precipitate suspensions. Moreover, adsorption of the flotation collectors by the precipitates as well as the rate of their sedimentation were measured. It was found that the extent of collector sorption, changes in the electrokinetic potential of precipitate grains and their aggregation affected the flotability and course of flotation of the examined precipitates. These dependencies were irregular and could be discussed in terms of chemisorption of collectors on the surface of the precipitate grains.
A new route to 4‐, 5‐, and 6‐indolecarboxylic acids
Authors: Kasahara Akira , Izumi Taeko , Yanai Hiroshi , Murakami Satoshi , Takatori Masayuki
Published: July 2010

There are many indole derivatives bearing carboxyl or methoxycarbonyl groups on the benzene ring and these often have patent physiological activities. Synthesis of these compounds usually starts from indoles having a halogen group at the desired position on an indole ring. We now report a facile synthesis of 4‐, 5‐, and 6‐indolecarboxylic acids from 2‐bromoaniline derivatives (1). The synthetic route is shown in Figure 1.
A comparative study of a fluidised bed reactor and a gas lift loop reactor for the ibe process: Part III. Reactor performances and scale Up
Authors: Schoutens Gerda H. , Guit Ruud P. , Zieleman Gerard J. , Luyben Karel Ch. A. M. , Kossen Nico W. F.
Published: July 2010

Continuous fermentations using Clostridium spp. DSM 2152 immobilised in calcium alginate beads to produce butanol and isopropanol from glucose were carried out in a fluidised bed reactor with liquid recycle (FBR, 10.9 dm3 working volume, 41 % solids) and in a gas lift loop reactor (GLR, 11.4 dm3 working volume, 32% solids). In the FBR in‐situ produced non‐coalescing gas bubbles had a negligible influence on the fluidisation pattern and the steady state results of the fermentation were in accordance with those predicted by a reactor model. The FBR was operated reliably for 5 weeks without decrease of activity. The GLR behaved as a three phase reactor because of the recycled fermentation gas. The steady state fermentation results were as predicted by the GLR model. Scale up to a 50 m3 FBR and a 65 m3 GLR led to development of a plug flow with recycle model for the FBR and a stirred tank model for the GLR. On the basis of overall reactor performance and ease of integration with a simultaneous product recovery the FBR is preferred to the GLR for application in a large scale butanol/isopropanol process using immobilised Clostridia spp.
Thermal properties of tetraalkoxysilanes
Authors: Alagar M. , Krishnasamy V.
Published: July 2010

Tetraalkoxysilanes were prepared by reacting SiCl4with alcohols in the liquid phase in the presence of pyridine. Based on the experimental evidence and theoretical calculations, tentative structures have been proposed. Thermal conductivity measurements for these samples were done over a temperature range 303–463 K and the data are compared with the theoretical values derived from empirical equations. In addition, other properties such as specific heat (Cp), thermal expansion (α) and oxidation stability were determined and the values are compared with the reported values for polymethy Isiloxanes.
Some styrene alkyl‐methacrylate copolymers as viscosity index improvers
Authors: Abou el Nage H. H. , Abd el Azeim W. M. , Zanib Fathy , Ibrahim Saad H.
Published: July 2010

Styrene alkyl‐methacrylate copolymers were synthesised at different monomer percentage ratios and under varied reaction conditions. Evaluation of obtained copolymers as viscosity index improvers in multigrade motor oils has been carried out in relation to different reaction variables and a comparative evaluation with commercially available viscosity index improvers in their performance properties (e.g. thermal oxidation and shear stabilities) was investigated.
Stabilisation in bacillus stearothermophilus of a recombinant plasmid carrying the homologous α‐amylase gene
Authors: Aiba Shuichi , Monden Yoshiaki , Ohnishi Masatoshi , Koizumi Jun‐Ichi , Ming Zhang
Published: July 2010

The phenotypic stability of the recombinant plasmid pAT9 (11.5 MD), which contained the cloned α‐amylase gene from B. stearothermophilus, was studied in batch and continuous culture. Irrespective of the type of culture (batch or continuous; or using glucose or maltose as carbon source), deletion plasmids of the phenotype KmrAmy− the same size (7.3 MD) emerged with time. DNA sequencing analysis and Southern hybridization of a region adjacent to both ends of the pAT9 HindIII fragment containing the α‐amylase gene showed that almost the entire part of the HindIII fragment was lost. Homology between fragments contiguous to the pAT9 HindIII terminals allowed exclusion of a fragment that did not encode the α‐amylase gene and a new recombinant plasmid, pATHP9 (KmrAmy+; 7.5 MD), was constructed which had enhanced phenotypic stability in B. stearothermophilus.
Kinetics of esterification of benzyl alcohol with acetic acid catalysed by cation‐exchange resin (Amberlyst‐15)
Authors: Roy Ratul , Bhatia Subhash
Published: July 2010

Esterification of benzyl alcohol with acetic acid catalysed by Amberlyst‐15 (cation‐exchange resin) was carried out in a batch reactor in the liquid phase in the temperature range 328–359 K and at 1 atm. The reaction rate increased with increase in catalyst concentration and reaction temperature. Resin particle size and stirrer speed had virtually no effect on the rate under the experimental conditions. The rate data were correlated with a kinetic model based on homogeneous reaction. The apparent activation energy was found to be 73.3 kJ mol−1 for the formation of benzyl acetate.
The growth of FeOOH microcrystals and chemisorption rate of NO
Authors: Kaneko Katsumi , Inouye Katsuya
Published: July 2010

The adsorption of NO over a period of 1 ms–1 min on α‐ and γ‐FeOOH with different degrees of crystallization has been examined in order to clarify the fast chemisorption phenomenon. The FeOOH crystals were prepared under the conditions of various reaction temperatures and ageing times. The changes in X‐ray diffraction patterns, particle size, specific surface area and electrical conductivity were examined. The fast chemisorption rate constant, kf, for NO was obtained at 30°C from the conductivity change in the initial stage of NO adsorption. The α‐FeOOH aged for 2 days and 6 days, the crystallite size of which approximately 100 Å gave the highest kf and the greatest amount of chemisorption; the high activity is assumed to be caused by a special surface structure accepting NO molecules. The maximum kf for α‐FeOOH was also for a crystallite size of approximately 100 Å. As the change of kf with crystal growth for γ‐FeOOH is similar to that of electrical conductivity, an electronic factor seems to be most important in the fast chemisorption process of NO on γ‐FeOOH.
Facilitated mass transfer in a packed‐bed immobilized‐cell reactor by using an organic solvent as substrate reservoir
Authors: Brink Lowie E. S. , Tramper Johannes
Published: July 2010

The production of propene oxide from propene and oxygen by non‐growing cells entrapped in calcium alginate was used to study the behaviour of a packed‐bed immobilized‐cell reactor operated with an organic solvent as the substrate reservoir. As a result of the high solubility of propene in the solvent used, n‐hexadecane, oxygen was considered to be the limiting substrate. Dilution of the biocatalyst bed with small glass particles appeared necessary to attain a high liquid/solid contacting efficiency between the hydrophilic gel particles and the hydrophobic solvent. The bed dilution had the advantage of avoiding bed compaction and reducing pressure drops. The use of an organic solvent as the transport medium prevented oxygen depletion along the length of the packed‐bed reactor. This eliminated the need for a separate gas phase in the bioreactor. A mathematical reactor model was developed to describe the combined effects of contacting pattern and external and internal diffusion limitations on the instrinsic kinetics of the immobilized cells. Experiments with the packed‐bed immobilized‐cell reactor were performed using an aqueous solution or n‐hexadecane as the reaction medium. Predicted oxygen conversions compared favourably to the observed values without the need for fitting factors.
Adsorption of petroleum sulfonate TRS 10‐80 on a mineral sand
Authors: Singh Vimal Sheel , Pandey Birendra Prasad
Published: July 2010

Adsorption of petroleum sulfonate TRS 10‐80 on a mineral sand, characterized by chemical analysis and infrared spectra to be silica, has been studied under conditions relevant to the practical field. The adsorption is significantly affected by the age of the sulfonate solutions. A new mechanism of adsorption involving sulfonate monomers and multimers has been proposed. The adsorption behavior is best characterized by Langmuir and Freundlich models. At higher temperatures, the mineral surface seems to be capable of forming chemical bonds with the sulfonate anions. Micelles are not considered to be the species favored for adsorption. The adsorption, depending upon the concentration of added electrolyte, either reaches a saturation value or decreases abruptly after a fixed surfactant concentration has been reached. The apparent surfactant loss at higher salt concentrations seems to be due to salting‐out of the sulfonate rather than its adsorption.
The application of ceramic membranes to the biological industries
Authors: Shackleton Ronald
Published: July 2010

The construction, design and configurations of ceramic membranes are described together with their properties, advantages and disadvantages. Some applications in the beverage and biotechnology industries are described together with plant layouts and results obtained.
Adsorption of pollutants on to activated carbon in fixed beds
Authors: McKay Gordon , Bino Murad J.
Published: July 2010

The adsorption of certain pollutants, namely phenol, p‐chlorophenol, sodium dodecyl sulphate and mercuric ions, on to activated carbon has been studied using fixed bed systems.

There are three main methods of contacting in solid/liquid adsorption systems, namely batch, fixed bed and fluidized bed systems. In fixed bed adsorption the adsorption rate is determined on the basis of adsorption equilibrium (unfavourable, linear, favourable or completely irreversible) and the controlling mechanism (external film mass transport, internal pore diffusion, internal solid phase diffusion or longitudinal diffusion). One or more of the previous transport mechanisms may be rate controlling depending on the solute‐adsorbent system. For an adsorbent like activated carbon which is highly porous both external transport and pore diffusion will be very important. An adsorption model, based on external mass transport and internal pore diffusion, has been applied to the systems to predict theoretical breakthrough curves. These curves have then been compared with experimental data and using a ‘best fit’ technique, an effective pore diffusion coefficient can be determined for each sorbate–carbon system.
Reaction of amines with conjugated olefins using lithium naphthalenide in non‐ethereal solvents
Authors: Sugahara Kotoji , Fujita Tsutomu , Watanabe Shoji , Hashimoto Hiroyuki
Published: July 2010

It was found that lithium naphthalenide can be prepared from metallic lithium cuttings and naphthalene in non‐ethereal solvents, such as benzene–N,N,N′,N′‐tetramethylethylenediamine (TMEDA) or benzene‐N,N,N′,N′‐tetramethyldiaminopropane (TMDAP), under ultrasonic irradiation. Secondary amines reacted with conjugated olefins, such as isoprene or myrcene, using lithium naphthalenide in such non‐ethereal solvents to give allylic amines. The yields of products were higher than in the reaction using lithium naphthalenide in tetrahydrofuran. From diethylamine (I) and isoprene (II), a mixture of N,N‐diethyl‐3‐methyl‐2‐butenylamine (IV) and N,N‐diethyl‐2‐methyl‐2‐butenylamine (V) (IV:V = 79:21) was obtained in 77% yield, and from diethylamine (I) and myrcene (III), N,N‐diethylgeranylamine (VI) and N,N‐diethylnerylamine (VII) (VI:VII = 88:12) were produced in 72% yield. These terpenic amines, VI and VII, are used as starting compounds for the preparation of perfumery materials.
Selective toluene disproportionation over ZSM‐5 zeolites
Authors: Meshram Namdeo R.
Published: July 2010

Selective toluene disproportionation to benzene and xylenes is investigated over HZSM‐5 and modified HZSM‐5 zeolites. The zeolites are modified with nickel, magnesium, phosphorus and boron, characterised by sorption, acidity measurement and X‐ray photoelectron spectroscopy, and their activity towards toluene disproportionation is discussed in the light of their physico‐chemical properties. The two types of active sites have been identified; one promoting disproportionation and the other cracking and dealkylation of toluene. It is found that the latter sites are suppressed due to incorporation of the modifiers. The modified zeolites are found to be para‐selective which appears to be consistent with the commonly accepted view that modifiers like magnesium, phosphorus and boron reside in the channels and react with Brønsted acid sites, leading to partial blockages and thus favouring the formation of p‐xylene. The effect of poisoning the zeolite with 1‐methylisoquinoline is also investigated. In the case of poisoned catalyst, p‐xylene is produced at levels up to 99%. The total elimination of other isomers from the products is suggested due to the selective poisoning of the non‐selective sites (on the external crystal surface) and to partial blocking of the pore openings.
Influence of roasting temperature on reactions between ferruginous blende and copper(II) oxide
Authors: Ghodsi Mehdi , Detournay Jacquy , Schrobiltgen Jean‐Marie , Naessens Georges
Published: July 2010

Thermal treatment in an oxidizing atmosphere of a mixture of raw blende (ZnS) and copper(II) oxide enhanced the formation of a mixed ferrite phase at temperature about 600°C. The composition established at 900°C was approximately (0.8 ZnO · 0.2 CuO)Fe2O3.

For the mixture ZnS–CuO, with 5 to 15% CuO by weight, less than 15% copper was involved in the formation of the spinel phase.

The increasing copper content in the mixture, roasted above 1000°C, favoured solubilization of iron, even in a weakly acid medium.
The effects of whey cations on the kinetic parameters of a model for the enzymic hydrolysis of lactose
Authors: Agbebavi J. Tonyi , Rouleau Denis , Mayer Raymond C.
Published: July 2010

The effects of whey cations (Ca2+, Mg2+) on the enzymic hydrolysis of lactose have been studied, at temperatures in the range 30–50°C, in a continuous stirred tank reactor (CSTR), using an immobilized β‐galactosidase (Novozym 231). A model for the variation of Vmax (the maximum rate in the Michaelis—Menten expression) in the presence of the ionic environment has been developed based on the Gouy electrical double layer concept and the liquid phase bimolecular process. In the presence of one cation (Mg2+), the mean value of the model parameter av, an approach distance including the hydration radius of the protein, was 27 × 10−10 m, almost identical to the value obtained by the crystal density method. When two cations (Mg2+ and Ca2+) were present simultaneously the value of Vmax as a function of the ionic strength showed a maximum which may be explained by the Stern adsorption modification of the Gouy theory.
The manufacture of microporous membranes and their structure and properties
Authors: Meares Patrick
Published: July 2010

Microporous membranes suitable for use in ultra‐ and microfiltration can now be made from a wide range of inorganic and organic materials. Inorganic membranes are made by methods derived from practices that are standard in the ceramics industry. Organic membranes are made from synthetic and modified natural polymers either in the dry state by exploiting anisotropic mechanical properties or from solutions of the polymer by one of the several versions of the phase inversion process. Thanks to the good understanding of the thermodynamic and kinetic properties of polymer‐liquid systems resulting from 50 years of careful research, the morphology of asymmetric membranes made by phase inversion can be controlled in fair detail. This short article surveys the methods of manufacturing membranes in relation to their structures.