bluuebunny/crossref_metadata_2025 huggingface dataset:
Continuous preparation of activated carbon supported zinc acetate catalyst and industrial synthesis of vinyl acetate from acetylene
Authors: Kawaguchi Toshio , Wakasugi Toshihisa
Published: July 2010

A continuous manufacturing method of an activated carbon supported zinc acetate catalyst has been established. Based on the dipping of a crushed activated palm carbon into a zinc acetate aqueous solution, the catalyst is prepared for the synthesis of vinyl acetate from acetylene in an industrial fluidized reaction vessel.

The relationship between the supported amount of zinc acetate and various factors has been studied. Based on these results, an empirical formula was developed. Using this formula, the continuous manufacturing apparatus was designed and constructed for the purpose of preparing the optimum supported fluidized catalyst. To minimize the activated carbon loss due to crushing and wearing, a vibrating conveyor system was employed.

This continuous manufacturing process produced a uniform catalyst with an activated carbon feed rate of 0.25 m3 h−1. Using this catalyst, a series of operational tests of the vinyl acetate synthesis was performed for investigating the optimum reaction conditions. These operational tests were carried out using an industrial fluidized reaction vessel of 3.28 m diameter and 50 tons day−1 vinyl acetate production capacity. Based on these test results, the reaction rate constant and the deterioration rate constant were newly introduced, and the optimum operation conditions were then determined.
Application of ultrafiltration to the preparation of defined hydrolysates of bovine haemoglobin
Authors: Piot Jean‐Marie , Guillochon Didier , Leconte Danielle , Thomas Daniel
Published: July 2010

Many uses of protein hydrolysates have been developed and applied to areas such as nutritional therapy, culture media, and the isolation of biologically active peptides. All these applications need carefully controlled and characterized hydrolysates. In order to produce such a type of hydrolysate, it is possible to use haemoglobin which is a very well defined and constant protein source. Enzymic hydrolysis of haemoglobin by pepsin was carried out at pilot‐plant scale in an ultrafiltration reactor with mineral membranes. The object was to obtain a reproducible, decolorized, salt‐free enzymic hydrolysate. Two types of membranes were tested having 10000 dalton (M5 type) and 20000 dalton (M4 type) cut‐offs. Little significant difference was observed in the final products when both types of membranes were used. Reproducibility of hydrolysates was verified by amino acid analysis and gel filtration chromatography. The haemoglobin hydrolysates produced contained more than 90% protein and are especially suitable for fine applications.
Adsorption of reaction species for hydrogenation of nitrobenzene on copper chromite at catalytic conditions
Authors: Choudhary V. R. , Sansare S. D. , Thite G. A.
Published: July 2010

Adsorption of nitrobenzene, aniline and water on copper chromite has been investigated at the temperatures (483–558 K) and partial pressures (0–40 kPa) involved in the catalytic process (viz. hydrogenation of nitrobenzene), using the gas chromatographic pulse technique. The adsorption of reaction species was found to follow the Freundlich adsorption isotherm. The data on isosteric heats of adsorption (at different surface coverages) were obtained from the adsorption isotherms. The results indicated that nitrobenzene and water are physically adsorbed, whereas aniline is chemisorbed on the catalyst. The variation in the heat of adsorption with surface coverage for the adsorption of aniline indicated the presence of surface heterogeneity on the copper chromite.
The stability conditions of the fed‐batch reactor. Part I: Monod type growth kinetics
Authors: Genon Guiseppe , Ruggeri Bernardo
Published: July 2010

The semicontinuous operation of a biological reactor consists of batch operation periods interspaced by withdrawal of part of the contents and its renewal in the form of fresh feed. This system has certain advantages with regard to productivity in some cases and also to the control. A study has been made of this mode of operation for Monod kinetics under both ideal conditions (perfectly mixed reactor, instantaneous withdrawal and renewal) and real conditions. An assessment is given of the operating limits (cycle time, reintegrated volume) within which stable condition can be obtained. A determination is also undertaken of reactor performance in terms of productivity, utilisation of the substrate and final concentrations by comparison with the corresponding parameter values for the chemostat.
Autoclaved gypsum plaster from selenite and by‐product phosphogypsum
Authors: Singh Manjit , Rai Mohan
Published: July 2010

Investigations were carried out to produce an autoclaved gypsum plaster (α‐hemihydrate) by heating the naturally occurring selenite and by‐product phosphogypsum under steam pressure in an autoclave. Various factors effecting the calcination of gypsum such as pressure, time of the autoclaving process and the particle size of gypsum lumps were investigated. The formation of hemihydrate was examined by periodic differential thermal analysis and weight loss determinations. The mineralogical studies of plaster were determined using microscopy and X‐ray diffraction. The data showed that complete inversion of gypsum into hemihydrate takes place by heating gypsum of particle size 15 to 20 mm3 at 1.75 kg cm−2 steam pressure for 7 h. The microscopy of plaster revealed formation of well‐defined euhedral prismatic and tabular shaped crystals showing a higher degree of crystallinity than the conventional β‐hemihydrate. The hydraulic properties of plaster were studied and it was found to possess considerable strength (230 kg cm−2). The α‐plaster has been found suitable for making masonry mortar and fibrous plaster boards according to the relevant Indian Standards for use in construction works.
The stability conditions of the fed‐batch reactor. Part II: Luedeking–piret type growth kinetics
Authors: Ruggeri Bernardo , Genon Giuseppe
Published: July 2010

The performance of a cyclic reactor was examined using a kinetic model allowing for inhibition by the metabolic product of the growth of microorganisms and production coupled with their growth and maintenance. The reactor's stability field was investigated through a search for cyclically stable solutions giving Sf ≠ O and Xf ≠ O. The productivity pattern and substrate utilisation as functions of the operating variables were studied within this field. Comparison of these results with those obtained with a Monod‐type kinetics leads to the conclusion that they are of general validity and do not depend on the kinetic model adopted.
Effect of interphase mixing on a water–organic solvent two‐liquid phase microbial system: ethanol fermentation
Authors: Bar Raphael
Published: July 2010

Ethanol fermentation by Saccharomyces cerevisiae was investigated in broth‐organic solvent two‐liquid phase systems with and without interphase mixing. The effect of interphase mixing with aliphatic alcohols as polar solvents and with alkanes as apolar solvents was determined from investigations in three distinct systems: a solvent‐saturated broth, a solvent‐broth dispersion system and a dispersion‐free solvent‐broth system.

Microbial activities, measured as a function of solvent volume and inoculum size, revealed that a dispersed polar solvent caused a longer growth lag time and a slower growth rate. Viability measurements showed that yeast cells were gradually killed in a dodecanol‐water dispersion system and not in a dispersion‐free one. This process was believed to be initiated and enhanced by cell adhesion to the solvent interface as observed under a microscope. Yeast activity was also measured as a function of an apolar solvent volume and inoculum size. A full fermentative activity was observed in an initially alkanesaturated broth unlike in an intermixed biphasic system. As a result of these investigations, it was concluded firstly that microbial activity in initially solvent‐saturated broths with and without contact with a stagnant solvent phase can be different and secondly that the process efficiency of a biphasic bioreactor, unlike that of a chemical reactor, can be hampered by interphase mixing.

The yeast activities in the presence of the various alcohols and alkanes were correlated with ‘log P’ values of the solvents. Full activity was observed at log P > 5 and almost none at log P < 4.
Effect of nitrous acid on antipyrine. II. Synthesis of fluoro‐organic derivatives
Authors: Abd‐Alla Mohamed A. , Atta Ferial M. , Abd‐Elmonem Maisa E. , Metwally Saoud A.
Published: July 2010

Interaction of antipyrine (I) with nitrous acid in the presence of excess sodium nitrite as buffer, followed by the addition of fluoroboric acid afforded the direct and short way to synthesis of antipyrine‐4′‐diazonium fluoroborate (II). Pyrolysis of (II) at 165°C gave 4′‐fluoroantipyrine (III). The structure of (III) was determined by IR and 13C NMR analyses.
Studies on bimetallic catalyst behavior during naphtha reforming
Authors: Das Shantanu , Srivastava Ramesh D. , Saraf Deoki N.
Published: July 2010

Reforming of naphtha over Pt–Sn/Al2O3 and Pt–Re/Al2O3 catalysts has been investigated. Addition of nitrogen accelerated the catalyst deactivation process, enabling the study of activity decline and subsequent regeneration. Effect of presulfiding on the activity, selectivity and regeneration capacity of the catalyst was also examined.

Presence of nitrogen promoted the dealkylation of C7 hydrocarbons, resulting in a higher initial benzene yield which declined with loss in catalyst activity. Sulfiding lowered the aromatics yield by blocking some of the active sites but deactivation rate declined, prolonging catalyst life between regenerations. Performance of Pt–Sn catalyst was similar to that of Pt–Re catalyst except that the aromatics yield was somewhat higher in the latter case.
A comparison between the performance of continuously stirred‐tank bioreactors and a TORUS bioreactor with respect to highly viscous culture broths
Authors: Krebser Urs , Meyer Hans‐Peter , Fiechter Armin
Published: July 2010

Two different designs of stirred‐tank bioreactor, the ‘conventional’ continuously stirred‐tank bioreactor (CSTR, 42 dm3 and 300 dm3) and a horizontal‐loop bioreactor (TORUS, 114 dm3) were used for the cultivation of Xanthomonas campestris, and their performances with respect to oxygen‐transfer rates and xanthan production were compared. The strictly aerobic yeast Trichosporon cutaneum was also cultivated in the TORUS bioreactor in a synthetic medium with up to 3% (w/v) xanthan added. Xanthan solutions are pseudoplastic and therefore an apparent viscosity at a shear rate (y) of 28.8 s−1 was used to compare the rheological behavior of the different test media. Maximal apparent viscosities of 1100mPa s were measured with xanthan concentrations between 20 and 25 g dm−3. With apparent viscosities of up to 800 mPa s, the performance of the TORUS bioreactor was found to be equivalent to the performance of the CSTR bioreactor in terms of oxygen transfer and xanthan production rates. However, the amount of glucose converted to xanthan was greater in the TORUS bioreactor. Since the power consumption for the TORUS is lower compared to that for the CSTR, this new design is an interesting alternative to the CSTR for the production of xanthan.
Adsorption of microorganisms on activated charcoal cloth: A material with potential applications in biotechnology
Authors: George Neil , Davies John T.
Published: July 2010

Adsorption studies of Escherichia coli and Saccharomyces cerevisiae to a new, flexible and robust activated carbon in the form of a cloth, have revealed it to be capable of removing large numbers of microorganisms from suspension. Under the conditions used, Langmuir‐type adsorption of E. coli was obtained and the monolayer coverage predicted by this adsorption isotherm was backed up by both microscopic examination and estimations of available surface area. Applications in fermentation technology, medicine and downstream processing have been suggested.
Parameters affecting adsorption of microorganisms on activated charcoal cloth
Authors: George Neil , Davies John T.
Published: July 2010

An experimental apparatus and protocol has been developed in which adsorption of microorganisms to activated charcoal cloth and the influence of various physicochemical parameters, including the effects of externally applied electrical potential, was examined. Unlike Langmuir‐type isotherms which were obtained when Ecoli adsorption was studied in revolving universal tubes, in the stirred cell described here multilayer isotherms were produced. The differences in adsorption trends were possibly due to differences in the hydrodynamic environment. Although under certain conditions long‐range electrostatic and electrodynamic forces seemed to influence adsorption, under the standard experimental conditions used, strong, nonbiological, close‐range interactions were occurring and cation bridging was implicated. Electrical polarisation of the activated charcoal cloth surface did not influence adsorption within the limits examined. Electrochemically induced aggregation in conditions where pH varied was observed, which was enhanced in the presence of MgSO4 and was associated with a precipitated material which appeared to bridge between the bacteria and the activated charcoal surface.
Dissolution kinetics of an oxidized copper ore in water saturated by chlorine
Authors: Ekmekyapars Ahmet , Clolak Sabri , Alkan Mahir , Kayadeniz Ilker
Published: July 2010

Dissolution kinetics of an oxidized copper ore (mainly malachite) in water saturated by Cl2 has been studied. The effect of particle size, flow rate of the gas, temperature and solid‐liquid ratio has been determined. The dissolution rate increased with decrease in particle size and solid‐liquid ratio and with increase in the gas flow rate and temperature. It has been found that the dissolution proceeds in two stages and is controlled by diffusion through the ash layer in each stage. The activation energies for the first and second stage are 27.15 and 20.21 kJ mol−1, respectively.
Isolation of high‐purity zirconia from Australian zircon sands using an ion‐exchange process
Authors: Ooi Choon W. , Hobday Malcolm D. , Bentata Albert
Published: July 2010

Zirconia produced by acid‐leaching zircon sand can be significantly contaminated by other elements leached from the sand. A simple cationexchange procedure has been developed that allows separation of the impurity elements from the zirconium to give zirconia with up to 99.99% purity. The addition of formic acid to the acid‐leach solution prior to ion exchange provides the removal of about three‐quarters of the hafnium present in the product zirconia.
Changes in intracellular sodium and potassium in chemostat‐cultivated Escherichia coli
Authors: Ratwatt Hiran A. M. , Wase D. A. John
Published: July 2010

Escherichia coli was continuously cultivated at constant dilution rate for a range of agitation rates, and at constant agitation rate over a range of dilution rates. Mean cell volume increased linearly both with increase in agitation rate (as we have previously found) and with increase in dilution rate. In each case, measurement of intracellular sodium and potassium content after rapid separation of cells from the medium by centrifugation through silicone oil showed these to increase as the mean cell volume increased. In absolute terms, the increase in sodium or potassium per unit cell volume was significantly greater for changes in agitation rate than for changes in dilution rate.
New approaches to the development of viral vaccines: Scientific and regulatory aspects
Authors: Robertson James S.
Published: July 2010

The revolution in biotechnology in the 1980s raises the possibility of producing vaccines which were hitherto difficult or impossible to produce by classical techniques. This revolution must be met by parallel considerations of appropriate evaluation and control procedures to ensure the safety and efficacy of such new vaccines. A significant problem of these new approaches is the difficulty in identifying a suitable subunit component able to induce a satisfactory protective immune response in the host. In addition vaccines produced in unusual cell substrates may contain contaminants not previously encountered by man. These and other problems are being met by the application of many of the control measures found useful in the past, by evaluation of all manufacturing processes, by the formulation of guidelines by international groups of experts, and by free international exchange of information on new problems of control as they arise.
The assessment of real hazards and appropriate counter‐measures: The clinician's view
Authors: Freestone D. S.
Published: July 2010

Biologicals whether or not produced by biotechnological techniques comprise a heterogeneous collection of substances which are derived from natural organisms or cells, or equivalent substances produced by synthesis, which are assayed by biological methods. These substances are used for various purposes in medicine and may be divided into three principal groups; vaccines, sera (including immunoglobulins and monoclonal antibodies) and biologically active proteins.

General concerns specific to the safety of biological products relate to possible adverse immunological interactions and the presence of contaminants: particularly viruses and bacteria, nucleic acids, and ‘additives’. Additives include impurities derived from the manufacturing and purification processes and materials deliberately added as preservatives or adjuvants. Each biological product demands individual review but in making assessments special consideration is needed of the extent of batch to batch variability and whether studies to confirm the absence of any increased frequency of neoplasia as a consequence of nucleic acid contamination should be pursued.

In the future more biologically active proteins will be produced including some which differ from natural proteins in being more specific in activity, of greater potency or with a different pattern of distribution metabolism and excretion. These and new monoclonal antibodies may interact immunologically with host tissues in unexpected and undesirable ways and demand the application of new specific preclinical and clinical screens.

The need for post marketing surveillance studies of an appropriate scale is no less for biologicals than for defined chemical entities.
Public perception of biotechnology hazards
Authors: Tait Joyce
Published: July 2010

So far the public reaction to new biotechnology industries has been largely benign, at least in the UK, but it is questionable how deeply held and how stable this attitude is. Biotechnology has some features in common with classic risk related issues, like nuclear power and pesticides, and could provoke an equally adverse public response.

This paper examines what we currently know about perceptions of biotechnology with the conclusion that the ‘public’ has yet to make up its mind. Factors that could influence the future public response include: rural social disruption caused by further increases in the productivity of agricultural land; any failure to control the new technology effectively, leading to a loss of public trust in the regulatory system; and intrinsic moral and ethical issues surrounding genetic manipulation, particularly in higher animals.
Oxide films on iron and iron‐copper alloys: An imaging atom probe investigation
Authors: Cornell Rochelle M. , Smith George D. W. , Cranstoun G. K. L.
Published: July 2010

An imaging atom probe has been used to analyse the oxide films formed by room‐temperature oxidation and atmospheric rusting on iron and on an ironcopper alloy. Both rusted and oxidised specimens field evaporated as Fe2+ Fe+, O+, FeO+ and FeO2+. In addition, hydroxylated iron species field evaporated from rust. Exposure of the specimen to sulphate ions during rusting led to incorporation of sulphate in the rust. Oxide films grown on the iron‐copper alloy were enriched in copper. Cu+ and Cu2+ field vaporated from this oxide, but CuO species were not detected. All the oxide films examined consisted of a mixture of amorphous iron hydroxide and magnetite. It is suggested that the copper in the oxide film may have been present as a substitutent in the magnetite lattice.
Effects of temperature and moisture on the anaerobic digestion of refuse
Authors: Kasali George B. , Senior Eric
Published: July 2010

The influence of the first‐tier variable temperature on the anaerobic decomposition of refuse was investigated by use of laboratory models. Temperature was found to exert significant effects on the interrelated metabolic processes of acidogenesis, solventogenesis and methanogenesis. A temperature elevation from a mean ambient regime (18.7°C) to 30°C resulted in a 2.6‐fold increase in the methanogenic rate while a 7.8‐fold increase was observed when the temperature was raised from 18.7 to 40°C. The rate of methanogenesis at 40°C was approximately three‐fold higher than at 30°C. Further temperature elevation to 55°C, however, resulted in the cessation of methanogenesis although solventogenesis was promoted. An attempt was made to extrapolate the results obtained to actual landfill, with specific reference to the role of refuse density in thermogenesis.
Mixing time in bioreactors
Authors: Kawase Y. , Moo‐Young M.
Published: July 2010

The mixing time in bioreactors is discussed. Theoretical correlations for the mixing time in stirred tank and bubble column reactors respectively, are derived. They are based on Kolmogoroff's theory of isotropic turbulence and the relationships between the mixing time and the axial dispersion coefficient in the turbulent flow regime. The predictions of the proposed correlations are in reasonable agreement with several available data and correlations. A wide divergence among the data for the mixing time reported in the literature is also discussed.
Microbial sensors: Fundamentals and application for process control
Authors: Riedel Klaus , Renneberg Reinhard , Wollenberger Ulla , Kaiser Gabi , Scheller Frieder W.
Published: July 2010

Microbial sensors consist of microorganisms in intimate contact with transducer devices converting the biochemical reaction to a quantifiable electrical response signal. The aim of this combination is the sensitive determination of a large spectrum of substances in various fields, especially in fermentation processes and pollution control. Microbial sensors for more than 50 different parameters have been described in the literature.

In this paper, the following main aspects are discussed: microbial and physical basis of microbial sensors, immobilization of microbes, principle of measurement, approaches for enhancing the selectivity and sensitivity of microbial sensors, applications in bioreactor and environmental control of microbial sensors.
Inhibition of phosphine liberation from amorphous red phosphorus
Authors: McCallum John J. , Alder John F.
Published: July 2010

An extensive study of the liberation of phosphine from commercial red phosphorus was undertaken. The influence of water, trace metals, magnesium, calcium and aluminium oxides and a selection of carbamates, phenols and quinones was investigated. Accelerated ageing tests at 50°C were used to assess the value of 1% (w/w) additions of p‐benzoquinone and 1,4‐naphthoquinone in particular, as inhibitors to the generation of phosphine from commercial phosphorus and a pyrotechnic composition including spindle oil and poly(vinylbutyral). The two quinones suppress the liberation of phosphine to < 5% the rate of generation from commercial unoiled phosphorus. The mechanism of phosphine generation is obscure, but involves dissociation of water in the phosphorus surface region and the formation of phosphorus acids which may disproportionate yielding phosphine. Alternatively, or simultaneously, hydrogenation of phosphorus may take place liberating phosphine. The quinones presumably arrest these processes by preferentially combining with hydrogen or free‐radical intermediates. The use of silver‐nitrate‐impregnated charcoal cloth and granules to remove gaseous phosphine was also studied.
Estimation of crystalline phase in ZSM‐5 zeolites by infrared spectroscopy
Authors: Shukla Dipak B. , Pandya Vyomesh P.
Published: July 2010

A fast and accurate method for identification and determination of purity of Zeolite Socony Mobil 5 (ZSM‐5) zeolite was developed using the IR optical density ratio of the bands at 550 and 450 cm−1 in the mid‐IR region of the structure spectra. The optical density values obtained from the proposed method, for ZSM‐5 zeolite synthesized, are compared with those of the Bayer ZSM‐5 zeolite used as reference material. For well‐crystallized calcined ZSM‐5 zeolite, this ratio is circa 0.8. This ratio is found to be less, if amorphous silicate is present in zeolite. The presence of a band at 550 cmSUP>−1 in addition to the one at 450 cm−1 shows that ZSM‐5 zeolite has been formed even if the material is X‐ray amorphous. The absence of the structure‐sensitive band at 550 cm−1 unambiguously indicates that such a zeolite has not been formed.
Effect of Carrier Matrix on Fermentative Production of Ethanol by Surface Immobilised Yeast Cells
Authors: Passarinho Paula C. L. V. , Vieira Ana M. S. , Cabral Joaquim M. S. , Novais JúLio M. , Kennedy John F.
Published: July 2010

The production of ethanol for potable preparations is well established and the traditional methods used therein are changing. More important, however, has been the advent of fuel alcohol, first in Brazil, but now with ever‐increasing possibilities of being adopted in North America and Europe. Production of alcohol by fermentation has therefore come to stay, and it is essential to discover ways of improving the productivities of such fermentations.

The effect of organic (cellulose and corn stover) and inorganic matrices (silica gel, porous silica, Celite and derivatised Celite) on the performance of ethanol fermentation by Saccharomyces bayanus was tested. The hydrophilicity degree of the support seems to play an important role in the ability of reaching high ethanol concentrations in the fermentation of 300 g dm−3 of glucose. Cells immobilised on carriers with low hydrophilicity degree, namely Celite, lead to better results (residual glucose: 56 g dm−3; ethanol: 111 g dm−3) than their free counterparts (residual glucose: 136 g dm−3; ethanol: 71 g dm−3).

Celite was selected for further cell immobilisation studies, including time of adsorption, whole cell concentration, initial glucose concentration and time of addition of the support to the fermentation medium. The latter has revealed to be a very important factor, improving the performance of ethanol fermentation by reducing the fermentation time. Previous immobilisation seems to have no effect when compared with the simple addition of Celite to the inoculated medium and the eficiency of Celite did not increase when the concentration of glucose was enhanced.
Aerobic treatment of branched alkylbenzene sulfonates
Authors: Hashim M. A. , Kulandai J.
Published: July 2010

Branched alkylbenzene sulphonates, recalcitrant xenobiotic compounds, were treated aerobically in a single‐tank activated‐sludge reactor and also by means of three continuous‐stirred‐tank reactors (CSTR) in series. For the single‐tank reactor it was observed that, the longer the hydraulic retention time, the greater were the reductions in biological oxygen demand (BOD), chemical oxygen demand (COD) and methylene blue active substances (MBAS). Reductions of 80%, 60% and 63% were achieved in the levels of BOD, COD and MBAS, respectively. In the case of the three‐CSTR system, acclimatization of the microorganisms was achieved 15 days after start‐up. For this system, the reductions in the levels of BOD, COD and MBAS were 80%, 68% and 69%, respectively.
Macrokinetics and mathematical modelling of quinone reduction by cyanobacteria
Authors: Kreysa G. , Krämer P.
Published: July 2010

The kinetics of the reduction of externally added 2‐hydroxy‐1,4‐naphthoquinone by blue‐green algae of the strains Anabaena PCC 7120 and Anacystis nidulans PCC 6301 were studied in aqueous cell suspensions by electrochemical monitoring of the concentration of the formed hydroquinone. This reaction is of potential interest for bioelectrochemical fuel cells. The experimental curves obtained could be interpreted by a model that takes into account that both substrate and product have to be transported through the microbial cell walls and that the conversion reaction takes place with firstorder kinetics within the microbial cells. No clear evidence was found for the involvement of photosynthesis. It is suggested that the reduction of the quinone probably occurs via the enzyme‐catalyzed oxidation of endogenous storage product(s), presumably glycogen.
Diffusion rates in a dense matrix of methane‐producing microorganisms
Authors: Nilsson Britt K. , Karlsson Hans T.
Published: July 2010

The diffusion rate of a species, in a dense matrix of methane‐producing microorganisms, was determined experimentally. To this end, a specially designed diaphragm diffusion cell was utilized. The experimental results revealed that the effective diffusion coefficient in a microorganism matrix was 22–33% of the diffusion coefficient in pure water.
Heterocyclic hansa yellow analogues: Synthesis of novel azodisperse dyes from 3‐oxo‐N‐(pyrazol‐4‐yl) butanamide as possible dyes for polyester fibres
Authors: Girges M. M. , Hanna M. A. , Elagamey A. A.
Published: July 2010

Different heterocyclic Hansa Yellow analogues were synthesized from 3‐oxo‐N‐(pyrazol‐4‐yl)butanamide for possible use as azodisperse dyes for dyeing polyester fibres. The free energy relationship between the position of absorption of these dyes‐λ‐and substituent Hammett sigma constants was investigated.
Nickel extraction from a nickel‐tungsten spent catalyst using column leaching
Authors: Kelebek S. , Distin P. A.
Published: July 2010

Nickel extraction from an uncrushed spent nickel‐tungsten catalyst was studied using sulphuric acid leaching in a column. The effects of flowrate, temperature and acid concentration on the cumulative nickel recovery was investigated using a three‐variable, two‐level factorial design. Statistical analysis indicated that among these variables only acid concentration was significant (at the 95% confidence level) in the ranges investigated. The catalyst can be leached either by a two‐step process or in a single step following catalyst preoxidation. In either case extractions exceeding 95% can be obtained. With oxidized samples, single‐step acid leaching at 82°C yielded significantly better nickel extraction than at 95°C. This was attributed mainly to tungstic acid precipitation in the catalyst pellets, an effect which occurs rapidly at 95°C and retards the leaching of nickel. Nickel extraction was also suppressed following preoxidation at over 300°C. This was thought to be due to formation of slow‐leaching nickel oxide‐tungstate. Following preoxidation at the optimum of 300°C, 97% of the nickel could be leached in 4 h at 82°C using (by volume) 3% sulphuric acid and 0.6% nitric acid flowing at 1.5 litres/h. About 70% of the nickel could be extracted from preoxidized catalyst using only water for 40 h at room temperature. These findings are incorporated in a simple proposed flowsheet.
Anaerobic sludge digestion using mesophilic‐thermophilic phase separation
Authors: Chang Tan C. , Wu Yeun C. , Ouyang Chua F. , Hao Oliver J.
Published: July 2010

Phase separation of sludge digestion was investigated using a suspended growth system for the acid phase and a fixed‐film system for the methane phase. A thermophilic temperature of 50°C was used in the methane reactor, while a mesophilic temperature of 37°C was maintained in the acid reactor. During the acid‐phase stage, the volatile acid concentration and the reduction of volatile solids averaged approximately 2200 mg dm−3 as acetic acid and 13% (w/v), respectively, under a hydraulic retention time of 2 days. These parameters were not significantly affected by the applied solids concentration. Reduction of the retention time in the acid reactor from 2 days to 1 day decreased the methane content (18% versus 28%) and the volatile solids destruction (8% versus 13%), but produced the same amount of volatile acids. The total gas production for 10 days overall retention time was slightly higher than that for conventional single‐phase sludge digestion. The significant cost saving in reactor volume and enhanced methane production may offset the increased energy consumption required for maintaining a thermophilic temperature during the methane phase.
Hydrodynamics of the flow transition from a bubble column to an airlift‐loop reactor
Authors: Verlaan Paul , Vos Jan‐Chris , Van T Riet Klaas
Published: July 2010

The hydrodynamics of an airlift‐loop reactor (ALR) and a bubble column (BC) were studied in the same reactor unit. When the liquid circulation in the ALR was impeded gradually in order to obtain a BC mode of operation, there was a transition flow regime inbetween that of the ALR‐type flow and the BC‐type flow. In the BC the heterogeneous flow was represented by an instationary circulatory flow pattern and characterized by a liquid circulation velocity. The liquid flow in the ALR was represented by a drift‐flux model. In the transition flow regime, hydrodynamic calculations based on the plug‐flow behavior of an ALR appeared to be valid up to a certain defined value of the total gas‐liquid flow rate. To distinguish between BC and ALR flow characteristics, a simple criterion is proposed, qualifying that the distinction between both flow patterns is determined by the superficial liquid velocity and the liquid circulation velocity. If the latter velocity exceeds the superficial liquid velocity a hydrodynamic transition will occur from a uniform ALR type of flow to a heterogeneous BC type of flow. The criterion coincides with an empirical power law function in which the liquid velocity is given as a function of the gas velocity. The values of the power‐law coefficients depended on the characteristics of the two‐phase flow. The change in value cohered with the onset of a change in the flow pattern.
Use of dimensionless parameters in design of cascade‐connected reactors
Authors: Muslu Yilmaz
Published: July 2010

General relationships applicable to a wide variety of bacterial mediated wastewater treatment processes have been developed using continuous‐flow stirred‐tank reactors (CSTR) arranged in series. Monod kinetics and mathematical models of reactors‐in‐series were used to represent the actual conditions resulting from varying degrees of axial dispersion and wastewater qualities. A numerical method was developed and effluent concentrations from an equivalent reactor series expressed based upon a plug‐flow reactor with the same inlet and outlet conditions. Using the numerical results obtained, a nomogram has been derived that enables the required hydraulic and solids residence times for a reactor with a given dispersion number to be determined, when inlet and outlet conditions and the coefficients of Monod kinetics are known.
Spectrophotometric determination of zinc in some aluminum base alloys
Authors: Zaki M. Tarek M. , Ragheb Abdel‐Ghani , Mohamed Adel S.
Published: July 2010

The complexation of zinc with hematoxylin was studied in the presence and absence of cetyltrimethylammonium bromide (CTAB). The sensitivity of the color reaction between zinc and hematoxylin was significantly increased by the sensitizing action of CTAB. The optimum range of pH for complex formation was 7.3±8.0. The molar absorptivity of the complex was 6.3 × 104 liter mol−1 cm−1 at 610 nm and Sandell's sensitivity was 0.001 μg cm−2. Beer's law was obeyed up to 0.92 μg of zinc per ml. To determine zinc in aluminum base alloys, a preliminary solvent extraction separation of zinc from 2M hydrochloric acid solution with tri(iso‐octyl)amine in isobutyl methyl ketone was carried out.
Anaerobic digestion kinetics of wine‐distilleries wastewaters
Authors: Sales D. , Valcarcel M. J. , Romero L. I. , De La Ossa E. Martinez
Published: July 2010

Experimental results of anaerobic digestion of wine‐distilleries wastewaters are compared with those obtained from two theoretical kinetic models: the substrate utilization model and the methane fermentation model. Both models predict accurately the performance of this depurative process, except at retention times less than 3 days, because the systems works under non‐steady state conditions.

For depuration levels greater than 95%, optimum retention time is 6 days, and methane volumes (at STP) produced per gram of substrate added to the digester are 0.24 dm3 g−1 chemical oxygen demand.
Study on the acid hydrolysis of peat: Composition of the extracts from Sphagnum peat
Authors: Martin Antonio M. , Manu‐Tawiah Wireko
Published: July 2010

Peat and its derived products, such as peat extracts or hydrolysates, offer a variety of possibilities as raw materials for the development of chemical and biochemical processes. Utilised as a fermentation substrate, peat extracts could provide a variety of nutrients to culture media, besides carbohydrates. In this work, Sphagnum peat moss and its extract produced by H2SO4 hydrolysis were analysed for total carbohydrates, reducing sugars, nitrogen, lipids, ash, amino acids and minerals. The results are discussed and compared with previous data.
Continuous enzymatic synthesis of Z‐kyotorphin amide in an enzyme‐immobilized fixed‐bed reactor
Authors: Clapés Pere , Mata‐Alvarez Joan , Valencia Gregorio , Reig Francesca , Torres Josep L. , García‐Antón José‐María
Published: July 2010

α‐Chymotrypsin immobilized on natural and inexpensive supports such as diatomaceous earth was used as catalyst for Z‐Tyr‐Arg‐NH2 (Z‐kyotorphin amide) synthesis. In order to obtain the optimal reaction conditions, a 22 factorial experimental design was used. The factors considered were cosolvent (dimethylformamide) concentration and temperature; optimal product yield was achieved at 40% (v/v) dimethylformamide and 25°C. A sequential kinetic model was considered which generally gave good agreement between experimental and theoretical data for continuous synthesis of Z‐kyotorphin amide in a packed‐bed immobilized reactor system. The activation energy for the synthesis was determined to be 48.0 ± 2.3 kJ mol−1.
Marine coatings based on metal complexes of 4‐amino‐3‐hydrazino‐5‐thio‐1,2,4‐triazole
Authors: Tadros A. B.
Published: July 2010

Copper, cobalt, nickel and tin metal complexes of 4‐amino‐3‐hydrazino‐5‐thio‐1,2,4‐triazole (I) have been prepared and their structure identified through IR and electronic spectra measurements.

The cobalt and nickel have been found to be octahedral; on the other hand, a mixed structure is proposed for the copper complex. The complexes are incorporated in marine paint formulations in the presenceo of 4‐(p‐chlorobenzylideneamino)‐3‐(p‐chlorobenzylidenehydrazino)‐5‐thio‐1,2,4‐triazole, 4‐(3,4‐dichlorobenzylideneamino)‐3‐(3,4‐dichlorobenzyl idenehydrazino)‐5‐thio‐1,2,4‐triazole and 4‐(p‐nitrobenzylideneamino)‐3‐(p‐nitrobenzylidenehydrazino)‐5‐thio‐1,2,4‐triazole. Each paint was applied to PVC and mild steel substrate and the panels were tested in Alexandria eastern harbour water. Paints containing copper, cobalt and nickel complexes of (I) in the presence of its chlorinated or nitro derivatives showed antifouling properties till about 4 months, while they protect steel substrate from marine corrosion for 1 month.
Effect of temperature and ph on the adsorption of an anionic detergent on activated carbon
Authors: Leyva‐Ramos Roberto
Published: July 2010

Adsorption of an anionic detergent (sodium dodecyl benzene sulfonate) from aqueous solutions onto activated carbon is investigated as an alternative for eliminating detergents from wastewaters. The adsorption isotherm was measured experimentally at 25°C, 30°C and 35°C and the experimental data were correlated reasonably well by the adsorption isotherm of Prausnitz‐Radke. The adsorption capacity is considerably affected by pH and there exists an optimal pH, near pH = 7, where the maximum adsorption takes place. The adsorption capacity increases with rising temperature, the adsorption is irreversible and the heat of adsorption is lessened with the amount of detergent adsorbed and its order of magnitude corresponds to a chemical reaction. It is concluded that the detergent is chemically adsorbed onto the activated carbon.
Barium aluminate hydrates—VI. 2BaO.Al2O3.5H2O and 2BaO.Al2O3.H2O
Authors: Ahmed A. H. Moinuddin , Glasser Lesley S. Dent
Published: July 2010

The compound 2BaO.Al2O3.5H2O has been synthesised and studied by infra‐red, X‐ray and thermal analytical techniques. The compound of approximate formula 2BaO.Al2O3.H2O forms as a dehydration product. The results are interpreted in terms of the known structure.
Factors influencing the reduction of barium sulphate
Authors: Hargreaves Keith , Murray David M.
Published: July 2010

The reduction of pure barium sulphate and of barytes to barium sulphide and soluble barium compounds has been carried out in an indirectly heated tube furnace using carbon as the reducing agent. Increasing the reduction temperature increases the yield of barium compounds. The best yield is obtained with a reduction period of 1–2 h at 850–1100°C, while excluding air during the reduction and subsequent cooling process.

The influence of ferric oxide and silica impurities on the yield of soluble barium products has been studied at a reduction temperature of 1000°C. Both reduce the yield of soluble barium products, ferric oxide having a much greater effect. The effect of these two impurities is not additive, silica minimizing the effect of ferric oxide.
Synthesis of 7‐amino‐4‐methylcoumarin (AMC) derivatives and their hydrolysis by plant cysteine proteinases
Authors: Gray C. J. , Sullivan J. M.
Published: July 2010

A number of derivatives of citrullyl‐7‐amino‐4‐methylcoumarin (Cit‐AMC) have been synthesised and characterised. Their hydrolysis, releasing the fluorescent 7‐amino‐4‐methylcoumarin, by the plant cysteine proteinases papain, ficin and bromelain was examined. Two derivatives in particular, Z‐Phe‐Cit‐AMC and Z‐Gly‐Phe‐Cit‐AMC, were shown to be good substrates for these enzymes. The possible use of the fluorogenic peptides in assays for these enzymes is discussed.
High density culture of Coptis japonica cells increases berberine production
Authors: Matsubara Koichi , Kitani Shigekazu , Yoshioka Toshihiro , Morimoto Teijiro , Fujita Yasuhiro , Yamada Yasuyuki
Published: July 2010

A high density culture method was devised to improve the yield of berberine from highly productive cells of Coptis japonica. By adjusting aeration and stirring, Coptis cells were cultured at densities of up to 75 g dm−3 (dry weight) in a culture tank fitted with a hollow‐paddle type stirrer.

Whereas a maximum density of 30 g dm−3 of C. japonica cells could be used in ordinary batch culture, 48 g dm−3 could be used in a fed‐batch culture in which the amounts of the nutrients in the medium were made proportional to the density of the inoculum. Moreover, in fed‐batch culture done with modified medium, the composition of which had been determined from the amounts of components incorporated in cells grown at the usual density for ordinary batch culture, the cell yield was improved to 55 g dm−3 and the berberine yield to 3.5 g dm−3.
Fractionation techniques in process biotechnology
Authors: Scawen Michael D. , Hammond Peter M.
Published: July 2010

The application of fractionation techniques to protein purification at a process or industrial scale is reviewed. The principles of various chromatographic separations are described and the choice and selection of available matrices discussed. Gel filtration, ion‐exchange hydrophobic interaction and affinity chromatographic techniques can all operate at process scale. HPLC is particularly suitable for process development and scale up without loss of efficiency. Magnetic separation, solvent partitioning and electrophoresis also offer potential for process scale operation. Recent developments also include improved matrices and the application of genetic engineering techniques to design proteins for efficient separation.
Partial oxidation of propylene MoO3/iron tellurite catalysts
Authors: Arriagada R. , Reyes P.
Published: July 2010

The catalytic behaviour of the series Fe2(TeO3)3 + × % MoO3 (X = 0–30 mol. %) in the oxidation of propylene in the gaseous phase has been studied. It has been found that the addition of Mo03 to the iron tellurite activates the reaction towards the partial oxidation to acrolein. From the characterisation of solids it is possible to conclude that the addition of MoO3 promotes the crystallinity of the iron tellurite. On the other hand, surface studies of the catalysts show that depending on the MoO3 loading, this component is present in various states which contribute in different ways to the catalytic action. Some explanations for the observed behaviour are proposed.
Review of the hydrolysis of iron(III) and the crystallization of amorphous iron(III) hydroxide hydrate
Authors: Cornell Rochelle M. , Giovanoli Rudolf , Schneider Walter
Published: July 2010

Hydrolysis of ferric solutions leads initially to mono‐ and dinuclear species which interact to produce further species of higher nuclearity. These polynuclear species age eventually to either crystalline compounds or to an amorphous precipitate (amorphous iron(III) hydroxide hydrate).

Amorphous iron(III) hydroxide hydrate is thermodynamically unstable and gradually transforms to α‐FeO(OH) and α‐Fe2O3. These crystalline products form by competing mechanisms and the proportion of each in the final product depends on the relative rates of formation. The master variable governing the rates at which these compounds form is pH. Other important factors are temperature and the presence of additives.

Most additives retard the transformation and by suppressing formation of α‐FeO(OH) lead to an increase in the amount of α‐Fe2O3 in the product; some additives also directly promote formation of the latter compound. Metal ions can oftxen replace a proportion of Fe in the α‐FeO(OH) and α‐Fe2O3 lattices. At high enough concentrations they can induce formation of additional phases. Additives may also modify the morphology of the crystalline products.
Facilitated transport of benzylpenicillin through immobilized liquid membrane
Authors: Marchese José , López Jorge L. , Quinn John A.
Published: July 2010

The rate of benzylpenicillin transport, as an ionic pair with a tetrabutyl ammonium cation, from aqueous media through a liquid membrane consisting of n‐decanol supported in a porous Teflon membrane has been investigated as a function of the chemical composition of the system and the hydrodynamic conditions at 25°C. The measured transfer rates have been explained in terms of the diffusion of the ionic pair species through the liquid membrane. The results are in agreement with theoretical predictions and it is demonstrated that the transport of benzylpenicillin takes place against a concentration gradient.
Mathematical modelling of landfill degradation
Authors: Young Alan
Published: July 2010

This paper presents a mathematical model for the primary and secondary stages of biodegradation within domestic landfills. Quantitative relations are proposed to describe the rates of mass conversion between the major landfill chemicals and the effects of gas evolution. Particular attention is given to the methanogenic stage with the associated bacterial population being modelled explicitly. The processes are phrased in terms of a system of coupled differential equations, and examples of their numerical solution are given for cases in which spatial dependency is neglected. The main inadequacies of this model and the need for more appropriate data are indicated.