bluuebunny/crossref_metadata_2025 huggingface dataset:
An affinity adsorbent derived from aminopropyl silica for serine protease chromatography
Authors: Chang Ru‐Mu , Lee Wen‐Chien
Published: May 2005

A silica‐based adsorbent for affinity chromatography of serine protease was prepared by bonding p‐aminobenzamidine (pABZ) to aminopropyl silica. Silanization of silica with both γ‐aminopropyltrimethoxysilane and γ‐amino‐propyltriethoxysilane under anhydrous conditions led to a monolayer density of primary amino groups. The aminopropyl silica was converted to primary hydroxylcontaining silica via diazotization, and consequently activated with p‐nitrophenyl chloroformate and immobilized with ligand pABZ. The resultant silica–pABZ has a ligand density of 13.8 μmol g−1. Pyridine was indicated by the data to increase the reactivity of the chloroformate toward the hydroxyl group more efficiently than 4‐dimethylaminopyridine. Two stages of adsorption were found in batch adsorption of trypsin with an equilibrium adsorption isotherm of the Langmuir type. When the chromatographic column packed with this silica–p ABZ was operated under a higher flow rate (2·33 cm3 min−1) and with 3 g dm−3 of crude urokinase as the influence, the yield was 55%. Both the flow rate and the concentration of the crude protein were shown, by measuring the dynamic binding capacity from chromatographic experiments, to be the factors which influenced the chromatographic efficiency.
Physicochemical factors affecting the formation of the biological response modifier scleroglucan
Authors: Taurhesia Shelly , McNeil Brian
Published: May 2005

The use of phosphate as the limiting nutrient for scleroglucan formation by Sclerotium glucanicum led to stimulation of glucan formation. Final exopolysaccharide concentrations achieved in phosphate‐limited (18·9 kg m−3) cultures were much higher than in the usual nitrogen‐limited fermentations (11·4 kg m−3). The mechanism by which phosphate limitation engendered glucan formation may be largely non‐specific, involving a generalised diversion of the carbon source away from biomass formation and towards glucan synthesis. The effect of stirrer speed was examined in a fermenter fitted with a 6‐bladed Rushton turbine impeller of 0·5 vessel diameter. It was noted that biomass and scleroglucan formation showed different optima. This may have been due to the markedly different oxygen requirements of the two processes.
1,4‐Dihydroxyanthraquinone‐2‐carboxamides and 2,3‐dicarboximides. Orange dyes for synthetic polymer fibres
Authors: Peters Arnold T.
Published: May 2005

Hydrolysis of 1,4‐dihydroxy‐2,3‐dicyanoanthraquinone gives 1,4‐dihydroxyanthraquinone‐2,3‐dicarboxylic anhydride, reaction of which with alkylamines and arylamines gives either the 2‐carboxamide or 2,3‐dicarboximide derivatives. These compounds colour polyester in brownish‐orange hues having good light fastness. The colour of the dyes is discussed in relation to other 2‐substituted derivatives of 1,4‐dihydroxyanthraquinone.
A comparative study of effects of soy and corn flours on the evolution of alcohol fermentation in successive batches
Authors: Maia Amazile B. R. A. , Nelson David L.
Published: May 2005

The evolution of alcohol fermentation in ten successive batches was analysed using three distinct media, all containing commercial sucrose as substrate. The first medium contained mineral salts and yeast extract, the second contained only soy flour as the nutrient source and the third only corn flour. The alcohol contents and yeast viabilities were determined during ten successive batches with each medium. There was no significant differentiation in ethanol yield during the total period of tests (60 h with each medium). However, the medium containing soy flour showed the best evolution of yeast viability. The best specific productivity of ethanol was obtained with the medium containing corn flour, which justifies the traditional and empirical use of the component in the fermentation step by the small producers of sugar cane spirits in Brazil.
Rational design of metal mesh particles for biological fluidized bed reactors
Authors: Kargi Fikret , Toprak Hikmet
Published: May 2005

Utilization of metal mesh particles as a support material in biological waste treatment and fermentation technology offers special advantages over other immobilization methods. A theoretical analysis of fluidized bed bioreactors utilizing metal mesh support particles is presented and optimization of important parameters for rational design of metal mesh particles is discussed.
Selectivity aspects in the multi‐phase hydrogenation of α,β‐unsaturated aldehydes over supported noble metal catalysts: Part I
Authors: Satagopan V. , Chandalia Sampatraj B.
Published: May 2005

The selective hydrogenation of cinnamaldehyde and other unsaturated aliphatic aldehydes under a two‐phase liquid system using toluene and aqueous alkaline solution over supported palladium catalysts has been investigated with a view to obtaining the corresponding saturated aldehydes with sufficiently high selectivities. In the case of cinnamaldehyde, the effects of various process parameters on the reaction rate and selectivity with respect to the aldehyde have been investigated. The results obtained are likely to be useful for the rational design of the process for the production of industrially relevant products, such as hydrocinnamaldehyde and citronellal using cinnamaldehyde and citral as the starting materials.
Activity of ruthenium hydrogenation catalysts in copper(II) formate decomposition
Authors: Kluson Petr , Cerveny Libor , Krivska Marie , Had Jiri , Laurentova Simona
Published: May 2005

Charcoal‐, silica‐, alumina‐ and titanium(IV) oxide‐supported ruthenium catalysts, prepared by conventional impregnation and incipient wetness methods from a ruthenium(III) oxide precursor were tested in copper(II) formate decomposition in aqueous solution. Such a reaction was found to be an efficient and simple activity test of charcoal‐supported catalysts. The application of this reaction for a bimetallic ruthenium–copper catalyst preparation was also suggested. Experimental results were compared with those obtained using commercial catalysts and ruthenium black.
Kinetic model for substrate utilization and methane production during the anaerobic digestion of olive mill wastewater and condensation water waste
Authors: Martín Antonio , Borja Rafael , Banks Charles J.
Published: May 2005

A kinetic model to describe the anaerobic digestion of olive mill wastewater (OMW) and condensation water from thermally‐concentrated OMW has been developed. Two complementary kinetic descriptions, for substrate utilization and methane production, were derived. The model equations accounted for extracellular hydrolysis of complex substrates (OMW) and considered the hydrolysed products as the limiting substrates for cell growth and product formation according to Monod kinetics. Predicted relationships agreed well with experimental data. When extracellular hydrolysis was required and rate limiting, as in the case of the OMW, the equations were reduced to a Contois‐type form. However, if no extracellular hydrolysis of the substrate was involved, as in the case of the condensation water from thermally‐concentrated OMW, the equations were in the form of a Monod‐type relationship. Thus, the equations represented a generalized kinetic expression for anaerobic fermentation relating the Monod and Contois equations, which held in the two extreme cases.
Enzymatic resolution of 1‐hydroxy‐2,3‐dihydroindene and 1‐hydroxy‐1,2,3,4‐tetrahydronaphthalene derivatives using lipases
Authors: Izumi Taeko , Murakami Satoshi
Published: May 2005

1‐Hydroxy‐3‐methyl‐2,3‐dihydroindene and 1‐hydroxy‐1,2,3,4‐tetrahydronaphthalene derivatives were kinetically resolved with lipases by transesterification using vinyl esters or butyric anhydride as acyl donors. These results are discussed in considering the influence of acyl donors and with reference to Prelog's proposal that certain enzymes exhibit ‘product stereospecificity’.
Use of INT to determine the respiratory activity of immobilised and free Penicillium chrysogenum
Authors: Mussenden Paul J. , Bucke Christopher , Saunders Gunter , Keshavarz Tajalli
Published: May 2005

The specific oxygen uptake rates (OUR) of k‐carrageenan‐immobilised and free cell cultures of Penicillium chrysogenum were determined using an oxygen electrode in a closed chamber. This was compared with the respiratory activity determined by the extent of staining with iodonitrophenyl tetrazolium chloride (INT). The degree of INT staining correlated with the OUR; an increase in INT deposition corresponding to an increase in the measured OUR. The INT staining technique could therefore be used to determine cell respiratory activity. In this way a profile of fungal cell activity throughout immobilised cell aggregates and free cell pellets was determined. In both types of cell culture, after the initial growth period only the peripheral biomass was observed to be active.
Characterization of extracellular thermostable xylanase from Chaetomium globosum
Authors: Gandhi Jagruti P. , Rao K. Koteswara , Dave Prafulla J.
Published: May 2005

This paper deals with the characterization of extracellular thermostable xylanase produced by Chaetomium globosum, an ascomycete fungus. The crude extracellular enzyme was found to have temperature and pH optima of 60°C and 5·0 respectively. The enzyme hydrolyses xylan to a mixture of xylo‐oligomers. Xylobiose and xylose are the major breakdown products.
Extraction equilibria of lead(II) from nitrate solutions with acidic organophosphorus compounds
Authors: Juang Ruey‐Shin , Lee Shwu‐Hwa
Published: May 2005

The distribution data were numerically analyzed for the extraction of trace lead(II) from 1·0 mol dm−3 (Li,H)NO3 media with toluene solutions of acidic organophosphorus compounds (HR), including di(2‐ethylhexyl)phosphoric acid (D2EHPA) and 2‐ethylhexylphosphonic acid mono‐2‐ethylhexyl ester (HEHEHP). The complex formulations were determined to be \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {{\rm PbR}_2 {\rm (HR)}},{\rm }\overline {{\rm PbR}_2 {\rm (HR)}_4 },{\rm and }\overline {{\rm Pb(NO}_3 {\rm )R}} $\end{document} for the D2EHPA system and to be \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {{\rm PbR}_2 {\rm (HR)}_{\rm 3} },{\rm }\overline {{\rm PbR}_2 {\rm (HR)}_4 },{\rm and }\overline {{\rm Pb(NO}_3 {\rm )R(HR)}} $\end{document} for the HEHEHP system. In this work, the equilibrium constants for the formation of these complexes were also given at 298 K.
Selective hydrogenation of citral over PtSn supported on activated carbon
Authors: Neri Giovanni , Donato Andrea , Milone Candida , Mercadante Lucina , Visco A. Maria
Published: May 2005

Hydrogenation of citral has been studied over Pt and PtSn catalysts supported on activated carbon. Under the conditions used the unsaturated alcohols, geraniol and nerol, were the main reaction products. Addition of a small amount of tin (20% at.) to Pt/C increases the overall catalytic activity whereas a decrease is observed at higher tin contents. Addition of tin leads also to an increase in the selectivity to unsaturated alcohols which reaches a value of about 90%. The higher selectivity and activity are attributed to an activation of the CO bond by tin ions.
Kinetic modelling of methanation reaction over a CoMo/SiO2 catalyst
Authors: Chen Hong , Adesina Adesoji A.
Published: May 2005

The methanation kinetics of CO over a bimetallic catalyst containing 6Co:1 Mo:4K:100SiO2 has been studied and compared with that over a 6Co:4K:100SiO2 monometallic catalyst. Nine models arising from carbide, enolic and Eley–Rideal mechanisms were considered and assessed with respect to the rate data obtained for each catalyst. Interestingly, all three models which were considered statically adequate involved the dissociative adsorption of H2 as the rate‐determining‐step (RDS). The modelling results also suggest that the introduction of Mo to Co altered the methanation behaviour of CO over cobalt kinetically but not mechanistically.
Immobilization of chitinase on a reversibly soluble–insoluble polymer for chitin hydrolysis
Authors: Chen Jyh‐Ping , Chang Ko‐Chang
Published: May 2005

Serratia marcescens chitinase was immobilized by covalent binding to a polymer (hydroxypropyl methylcellulose acetate succinate, AS‐L) showing reversibly soluble–insoluble characteristics with pH change. The immobilized enzyme (CHAS) was soluble above pH 5·2 and insoluble below 4·5, which offers advantages in that it can carry out hydrolysis of chitin particles in a soluble form yet be recovered after precipitation at low pH. CHAS has much higher activity than chitinase immobilized to a water‐insoluble carrier. The effects of pH and temperature on the activity and stability of CHAS, and the adsorption of CHAS to chitin were studied and compared with those of free chitinase. Following repeated pH cycles between 6·6 and 4·5, CHAS lost 30% of its enzyme activity during the first cycle due to protein release and enzyme denaturation, but substantially less activity was lost in the following cycles, with minimum enzyme denaturation. Chitin hydrolysis with CHAS could be carried out in a semi‐batch mode with intermittent enzyme precipitation and product removal, this can enhance product yield up to 1·4‐fold when compared with batch reaction.
Structural changes and surface properties of Cox Fe3—x O4 spinels
Authors: Said Abd El‐Aziz A. , Hassan Ehsan A. , El‐Awad Ahmed M. , Abd El‐Salaam Khalf‐Alla M. , Abd El‐Wahab Mohamed M. M.
Published: May 2005

The cobalt ferrite spinel oxide series, CoxFe3–xO4 (0 ≤ x ≤ 3), has been prepared by coprecipitation. The adsorption–desorption isotherms of all the compositions calcined between 200 and 600°C have been measured using nitrogen gas at −196°C. The structural and the phase changes were characterized by TGA and XRD techniques. The results obtained revealed that the transformation of γ‐ to α‐Fe2O3 was accompanied by a sharp decrease in the SBET values. The addition of Co2+ ions into Fe2O3 up to × = 0.6 led to an observable increase in the SBET value. This behaviour was attributed to the incorporation of Co2+ ions into the Fe2O3 lattice and the retardation of the phase transition of γ‐ to α‐Fe2O3. The minimum SBET values obtained at a lattice composition of × = 1·0 corresponded to the formation of a cobalt ferrite normal spinel which is associated with the existence of narrow pores. The increase in SBET values in the cobalt‐rich region, with a maximum at x = 2·6 is explained on the basis of the cationic replacement of Fe3+ ions in the Co3O4 lattice. Finally, calculation of pore volume distribution was carried out, in addition to Va–t plots, in order to study the nature of the surface porosity, which was found to be mesoporous.
Effects of the seed sludge on the performance of UASB reactors for treatment of toxic wastewater
Authors: Dangcong Peng , Xingwen Zhang , Qiting Jin , De Zhang , Liangkui Xiang
Published: May 2005

A comparative study of different sludges (anaerobic sewage sludge and anaerobic sewage sludge cultivated for 30 days) as the seed of UASB reactors for treatment of synthetic resin production wastewater was carried out on a laboratory scale. Significant differences in reactor performance were observed. With anaerobic sewage sludge seed, the reactor obtained a 71% COD removal efficiency and produced 2·94 dm3biogas per dm3wastewater under an organic loading rate of 4·5 kg COD m−3day−1. The sludge in the reactor was diffuse and possessed poor settling ability, which led to effluent SS as high as 1200 mg dm−3. However, with anaerobic sewage sludge cultivated with synthetic substrate for 30 days as a seed, the same reactor gave 78% COD removal efficiency and produced 3·5 dm−3biogas per dm3wastewater at the same loading rate. Moreover, the sludge in the reactor was completely granulated and possessed good settling ability, which resulted in effluent SS as low as 200 mg dm−3. The granular sludge produced less biomass per gram COD removed than the diffused sludge. Anaerobic sewage sludge cultivated for a short time could form the nuclei of granules for the reactor, allowing granulation to proceed smoothly. Therefore, sludge nuclei are a prerequisite of sludge granulation in UASB reactors for treatment of toxic wastewater.
Effect of carrier ionic properties on cellulase productivity by immobilized filamentous Trichoderma reesei
Authors: Zhaoxin Lu , Kumakura Minoru
Published: May 2005

Filamentous cells of Trichoderma reesei were immobilized by an adhesion method using carriers prepared by radition polymerization and the effects of the ionic properties of the carriers on cellulase productivity have been investigated. The cationic polymers were better than anionic polymers in the adhesion of the cells. Enzyme productivity was affected by the ionic property of the polymer, the concentration of the coating monomer and the hydrophobicity of the pre‐coating polymer.
Estimation of interfacial concentration of extractants from interfacial tension measurements
Authors: Prochaska Krystyna , Alejski K. , Szymanowski Jan
Published: May 2005

The use of the spline function, logarithmic polynomial, Szyszkowski and Temkin equations to estimate the extractant interfacial concentration are discussed. The distribution of the experimental data and its nonlinearity upon the approximation errors and the surface concentration are presented.

The error of the interfacial tension isotherm estimation depends upon the equation considered. The Temkin isotherm deviates significantly from the experimental data. The distribution of experimental data affects both the matching of the interfacial tension isotherm with the logarithmic polynomial and the surface excess isotherm. The best approximations (low approximation errors and lack of sensitivity upon experimental data distribution) are obtained with the use of the Szyszkowski equation and the spline function.
Kinetics of horseradish peroxidase‐catalysed polymerization and precipitation of aqueous 4‐chlorophenol
Authors: Nicell James A.
Published: May 2005

Hydrogen‐peroxide oxidoreductase (EC 1.11.1.7) from horseradishes catalyzes the polymerization and precipitation of aromatic compounds from aqueous solutions in the presence of hydrogen peroxide. This process has demonstrated good potential as a technique for the removal of toxic contaminants from wastewaters. Steady‐state, fully transient and pseudo‐steady‐state models of the horseradish peroxidase system have been developed to assist in the under‐standing of the dominant mechanisms of inactivation and to aid in the selection and design of an appropriate reactor system. Model validation was performed by comparing model predictions with experimental observations of the polymerization and precipitation of 4‐chlorophenol. Good agreement was found between experimental data and predictions of the fully transient and pseudo‐steady‐state models. The pseudo‐steady‐state model has the advantage of reduced complexity with a corresponding reduction in computation time required to solve model equations while maintaining the predictive ability of the fully transient model.
Multifunctional viscosity index improvers
Authors: Mohamed Mohamed M. , Abou El Naga Hamdi H. , El Meneir Mohamed F.
Published: May 2005

Styrene alkylmethacrylate succinimide phosphoric acid additives are synthesised and evaluated for use in multigrade crankcase lubricating oils as multifunctional viscosity index improvers having both antioxidant and dispersant properties. The synthesis is based on reacting styrene alkylmethacrylate (prepared by the reaction of styrene and 2‐ethylhexylmethacrylate at different styrene/methacrylate mole ratios under various reaction conditions) with maleic anhydride and tetraethylenepentamine in the presence of phosphoric acid. Comparative evaluation of the properties of the synthesised products (e.g., viscosity properties, shear stability, oxidation stability and dispersive power) with commercial additives showed they were suitable for use as viscosity index improvers.
Stability and proteolytic activity of papain in reverse micellar and aqueous media: A kinetic and spectroscopic study
Authors: Vicente Laura C. , Aires‐Barros Raquel , Empis José M. A.
Published: May 2005

The stability and proteolytic activity of papain were studied in reverse micellar systems, and in aqueous media. In reverse micelles the maximum activity obtained was 80% of the enzyme activity in aqueous solution. Higher papain stability was found in reverse micellar systems compared with that in aqueous solution with half‐lives of 24 and 10 days respectively. Electron spin resonance (ESR) spectroscopy studies of aqueous and reverse micellar systems were performed in an attempt to explain the observed enzyme stability and activity profiles. For this purpose a spin label—TEMPOacetamide—was covalently linked to the Cys‐25 residue of the papain active center. ESR spectra of labeled papain indicated that catalytic activity of papain could be related to the conformational rigidity near the reaction center. The lower activities obtained in reverse micelles could be a result of the greater degree of mobility and polarity observed in these systems, which can be attributed to papain unfolding. The greater stability found for papain in reverse micelles could be the result of the limited extent of this denaturing process owing to the organized surfactant molecules around the enzyme.
Catalysis by intermetallic compounds III. The hydrogenation of buta‐1,3‐diene catalysed by cePd3–xAux alloys
Authors: Bahia Amrik , Harris I. Rex , Winterbottom John M.
Published: May 2005

The intermetallic alloy series CePd3–x Aux (0 ≤ x ≤ 1) has been prepared from its constituent elements by carbon arc melting and employed as catalysts for the hydrogenation of buta‐1,3‐diene at 1 bar (101·5 kPa) total pressure in the temperature range 50–120°C. Selectivities for butene formation and initial butene distributions were very similar to those measured for CePd3 and Pd‐rich CePd3–x Pdx alloys. Activity measurements showed that CePd2Au, was about three times more active than CePd3 despite having a surface which was shown by Auger electron spectroscopy (AES) to be deficient in Pd compared with the bulk and also compared with CePd3. Although a relationship appears to exist between catalyst activity and bulk electronic properties it can be only fortuitous and the surface electronic structure must be the important factor especially in view of the palladium‐deficient surface.
Heavy metals in the environment Part III. Anion exchange properties of poly‐4‐vinyl pyridine from acid chloride solutions
Authors: Chaudhary Abdul J. , Donaldson John D. , Grimes Susan M. , Boddington Stephen C.
Published: May 2005

The metal extractive properties of poly‐4‐vinyl pyridine, prepared in the free base form, were studied for Cu2+, Ni2+, Co2+, Zn2+ and Cd2+ in chloride solutions. The efficiency of metal extraction depended on the pH and composition of the solutions. For maximum metal extraction, the optimum initial pH of the solution was found to be within the range of 0·8 to 1·2 for WR/V ratios of 45 000–50 000 mg dm−3. The metal extractive power of the resin was found to increase as the metal chloride concentration of the solution was increased. A similar effect was found with all resin‐active metals when experiments were carried out in solutions containing high concentrations of KCl.
Biotreatment of coals and coal‐related compounds by hydrogen‐utilizing microorganisms
Authors: Murty Mangena V. S. , Aleem Muhammad I. H. , Kermode Richard I. , Bhattacharyya Dibakar
Published: May 2005

Desulfovibrio desulfuricans and Acidianus brierleyi were used to study hydrogenation of coal, pretreated coal, asphaltenes, and model compounds [diphenyl methane (DPM) and fumarate] under anaerobic conditions. This study involved three primary aspects: (1) determination of net hydrogen‐uptake, (2) identification of the biohydrogenated product of fumarate, and (3) testing the influence of hydrogen uptake/biohydrogenation of coal in terms of direct liquefaction yield. The net hydrogen uptake values (from Warburg and GC assays) by the coals or the model compounds (controls) were less than that of the biotreated samples. The greated hydrogen uptake (net, 1878 μmol g−1; coal control, 245; cell control, 127) occurred in untreated coal KCER No. 4677 in the presence of D. desulfuricans. The net hydrogen uptake by coals varied depending upon the coal type and the microorganism. Model compound DPM showed its highest hydrogen uptake rate when catalysed by D. desulfuricans (150 μmol g−1 h−1). D. desulfuricans also hydrogenated 36% of the fumarate to succinate in the presence of hydrogen.

Biotrated coal KCER No. 4677 (with 1878 μmol H2 g−1) was subsequently subjected to direct liquefaction. It showed a net increase in liquefaction yield of 5·4% as a result of the biotreament.
Characterization of activated carbon produced from almond shell and hazelnut shell
Authors: Balci Suna , Doǧu Timur , Yücel Hayrettin
Published: May 2005

Ammonium chloride‐impregnated and untreated almond shell and hazelnut shell samples were carbonized in a flow of nitrogen at relatively low temperatures. Pore structure characterization and sorption capacities of activated carbons prepared from shells of almond and hazelnut indicated that treatment with NH4Cl increased the total surface area and improved sorption characteristics. Chemical activation carried out at 350°C gave products with surface area values above 500 m2 g−1. On the other hand, the surface area values observed for the products obtained from untreated raw materials were about half of this value. The surface area of products obtained from NH4Cl‐impregnated samples reached values of over 700 m2 g−1 when the carbonization temperature was increased 700°C.
Kinetics of lactose isomerisation to lactulose in an alkaline medium
Authors: Dendene Kamel , Guihard Laurence , Nicolas Stéphane , Bariou Bernard
Published: May 2005

The aim of this work was to determine easily and quickly the operating conditions for the industrial production of lactulose (rate of isomerisation, rate of lactose degradation, reaction time, temperature, pH). The kinetic equations of lactulose formation and lactose degradation in an alkaline medium (NaOH) were determined. Experiments were carried out at different OH− concentrations (0·5 × 10−2–19 × 10−2 mol dm−3) and at different temperatures (328–353 K). A kinetic model is presented which can be used to describe the experimental results and hence a procedure for industrial production.
Metformin‐selective PVC membrane electrode based on metforminium phosphomolybdate ion pair
Authors: Rizk Mahmoud S.
Published: May 2005

The (1:1) (phosphomolybdate:metformin) ion pair is used as the ion exchanger in preparing conventional plastic membrane electrodes for metformin (Mf) and its performance characteristics were studied. The electrode exhibited a linear response with a good Nernstian slope over a relatively wide concentration range. The calibration graph slope was constant at 57 mV per concentration decade at 25°C for up to 5 days with continuous soaking. Then the slope decreased as the time of soaking increased, reaching 42 mV decade−1 after 20 days. The changes in pH did not affect the electrode performance within the range 3.0–10.5. The standard electrode potentials were determined at different temperatures and were used to calculate the isothermal coefficient of the electrode (0.000695 V °C−1). The electrode showed a very good selectivity for Mf with respect to a large number of inorganic and organic cations. The standard addition method and potentiometric titration were used to determine Mf in pure solutions and in pharmaceutical preparations.
A flow injection system for simultaneous determination of starch and glucose concentrations
Authors: Umoh Enobong F. , Schügerl Karl
Published: May 2005

A flow injection analysis (FIA) system capable of simultaneously determining the concentrations of starch and glucose in samples was set up. The system consisted of glucoamylase (GA), glucose oxidase (GOD), (EC 1.1.3.4) and mutarotase (MUT, EC 5.1.3.3) immobilized on macroporous polymer packed in reaction cartridges was operated at 30°C. Glucose resulting from the action of glycoamylase or originally present in the samples was determined amperometrically. The starch was analysed with the system without needing prehydrolysis with α‐amylase, and inclusion of mutarotase was found necessary only when the sample originally contained α‐glucose. A linear detection range up to 1.5 g dm−3 and 4.0 g dm−3 was obtained for the streams from which glucose and total sugar concentrations were measured, respectively. The system was able to analyse up to 10 samples per hour.
Comparison of the catalysed decomposition of hydrogen peroxide over superconducting and insulating barium cuprates—kinetics of decomposition over Y2BaCuO5
Authors: Khalil Laila B. , Mourad Wedad E. , Rophael Magdy W.
Published: May 2005

Catalytic activities of two non‐conducting cuprates (Ba2Cu3O5, Y2BaCuO5) and a superconducting cuprate YBa2Cu3O7–δ, prepared by two different methods, were compared using H2O2 solution. The two non‐conducting barium cuprates were found to be about two orders of magnitude more active than the superconducting perovskite‐like YBa2Cu3O7–δ. The near coincidence of the kinetic curves for the catalysed decomposition of H2O2 over YBa2Cu3O7–δ, prepared either from the perovskite‐like Ba2Cu3O5 and Y2O3 or from its components, proves that Ba2Cu3O5 is essential in the formation of YBa2Cu3O7–δ. First‐order kinetics were observed for the catalysed decomposition of H2O2 solution over the non‐perovskite Y2BaCuO5 at the initial stages of the reaction, similar to that of the superconducting perovskite catalyst. A tentative scheme of the possible catalytic reactions for the decomposition of H2O2 solution over the insulator Y2BaCuO5 is given.
Adsorption of chlorophyll‐a from acetone solution on natural and activated bentonite
Authors: Pradas E. González , Sánchez M. Villafranca , Viciana M. Socías , Campo A. Gallego
Published: May 2005

The adsorption of chlorophyll‐a on bentonite desiccated at 110°C, untreated and acid‐treated with H2SO4 solutions over a concentration range between 0·25 and 2·50 mol dm−3, from acetone solution at 25°C has been studied. The adsorption isotherms may be classified as using Giles' classification, as type S (untreated sample and 0·25 mol dm−3 H2SO4‐treated sample), type H (0·50 mol dm−3 H2SO4‐treated sample) and type L (1·00 and 2·50 mol dm−3 H2SO4‐treated samples). This fact suggests that the bentonite surfaces (low, high and medium affinity, respectively) behave in differently relation to the adsorption of the chlorophyll‐a molecules. The experimental data points have been fitted to the Freundlich equation in order to calculate the adsorption capacities (Kf) of the samples; Kf values range from 0·43 mg kg−1 for the untreated bentonite up to 108·89 mg kg−1 for the 0·50 M H2SO4‐treated bentonite. The removal efficiencies (R) have also been calculated and range from 5·71% for the untreated bentonite up to 85·18% for the 0·50 M H2SO4‐treated bentonite.
Efficient fuzzy control strategies for the application of pH‐stat to fed‐batch cultivation of genetically engineered Escherichia coli
Authors: Jin Sha , Ye Kaiming , Shimizu Kazuyuki
Published: May 2005

In the cultivation of genetically engineered Escherichia coli it is very important to control the substrate concentration at an appropriate level in order to avoid the accumulation of acetate, thereby elevating the expression level of plasmid‐encoded protein. In this paper, a pH‐stat mode of fuzzy control was considered for the overexpression of β‐galactosidase in the fed‐batch cultivation of recombinant E. coli. In the simple pH‐stat fuzzy control, the response of pH change in the culture broth to the feeding rate of glucose was used to estimate the glucose consumption rate. In the modified pH‐stat fuzzy control, the glucose consumption rate was accurately estimated by using pH change and the change in the carbon dioxide content of the exhaust gas. With this control strategy, the cell density could be increased to 72 g DCW dm−3, which was twofold higher than that attained in the cultivation with the simple pH‐stat fuzzy control. The bulk β‐galactosidase concentration was increased to 4150 U cm−3, which was threefold higher than when the simple pH‐stat control was used.
Comparative sorption equilibrium studies of toxic phenols on flyash and impregnated flyash
Authors: Singh Binay Kr. , Rawat Narendra S.
Published: May 2005

In the present study, the sorption of toxic phenols, which include phenol, o‐cresol, m‐cresol, p‐cresol, o‐nitrophenol, m‐nitrophenol and p‐nitrophenol, has been investigated. The influences of various factors, such as particle size, impregnation of flyash (IFA), pH and temperature on the sorption capacity have been studied. Equilibrium modelling has been carried out using Langmuir and Freundlich isotherm equations and constants have been calculated under different conditions. Thermodynamic studies have also been carried out and values of standard free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) calculated.
Removal of phenol from coupling of talc and peroxidase. Application for depollution of waste water containing phenolic compounds
Authors: Arseguel Didier , Baboulène Michel
Published: May 2005

The degradation of phenol by a combination of horseradish peroxidase/hydrogen peroxide in the presence of talc, a natural abundant and low cost mineral, was investigated. Adsorption of the reaction products on the talc effectively protected the biocatalyst against contamination by oxidative products, thereby prolonging its catalytic action and leading to almost complete elimination of phenols in aqueous media. Suitable conditions for depollution of waste water containing phenolic substances were developed after optimization of various parameters (type and amount of talc, reaction duration).
Transport and hydrolysis of urea in a reactor–separator combining an anion‐exchange membrane and immobilized urease
Authors: Chen Dong‐Hwang , Leu Jen‐Chih , Huang Ting‐Chia
Published: May 2005

A membrane reactor–separator, in which an anion‐exchange membrane and a urease‐immobilized poly(vinyl alcohol) (PVA) membrane were clamped together to separate the feed solution and the stripping solution of a dialysis cell, was constructed. The urea in the feed solution passed through the anion‐exchange membrane, water film, and then was hydrolyzed to ammonium carbamate in the urease‐immobilized PVA membrane. The experimental results showed that no ammonium ion was found in the feed solution under either phosphate or citrate buffer systems at 0·05–0·2 mol dm−3 and pH 6–9, and various initial concentrations of urea in the feed solution (20–200 mmol dm−3). This indicates that the water film between two membranes allows the carbamate ions to decompose into ammonium and carbonate ions completely before entering the anion‐exchange membrane. The device therefore can be used for the removal of urea from feed solution, while preventing the backflow of ammonium ions from the stripping solution or water film into feed solution. It has significant potential in the development of a wearable or portable artificial kidney. The properties of the urease‐immobilized PVA membrane were examined. A kinetic model describing the transport‐reaction behavior of urea in the membrane reactor–separator was developed, and the optimum values of the reactor parameters were obtained.
Fluorine analysis of nuclear waste glasses
Authors: Matlack Keith S. , Labuda Tomasz
Published: May 2005

A method for analyzing the fluorine content of glass using a microwave oven to digest the glass is presented. Analysis time and secondary waste generation are reduced using this method, without sacrificing accuracy.
Metal sorption with extractant‐impregnated macroporous resins. 2. Chemical reaction and particle diffusion kinetics
Authors: Juang Ruey‐Shin , Lin Horng‐Chyuan
Published: May 2005

The rates of the sorption of zinc ions from aqueous sulfate solutions with di(2‐ethylhexyl)phosphoric acid‐impregnated Amberlite XAD macroporous resins were measured in finite bath by a batch‐contact time method. The sorption process was initially found to be controlled by a combined chemical reaction and particle diffusion process using a provable modified shrinking‐core model. A more rigorous model based on Fick's law was then developed to elucidate the sorption mechanism, and a procedure was suggested to simultaneously determine the reaction rate constant and effective particle diffusivity.
The influence of temperature on the growth and fatty‐acid composition of Skeletonema costatum in a batch photobioreactor
Authors: Sánchez Sebastián , de la Casa José A. , Martínez Ma Eugenia , Molina Emilio
Published: May 2005

The influence of temperature on the growth and fatty‐acid composition of the microalga Skeletonema costatum (CCAP 1077/b) has been studied. The maximum specific rates of growth (μm) and productivity (PB) were reached between 293 and 298 K. The experimental values of μm–T were adjusted to the function: μ = μ′o · T · exp(‐Ea/RT) − μd · exp(‐Ed/RT). The total content of the saturated acids reached a minimum at 293 K, wheras the maximum amounts of polyunsaturated acids and Σn − 3 HUFA (highly unsaturated n − 3 fatty acids) occurred at 293 and 295·5 K, respectively.
Removal and recovery of mercury from chloride solutions by contact deposition on iron felt
Authors: Grau Javier M. , Bisang José M.
Published: May 2005

This paper deals with the use of iron felt as a reducing agent for the removal of mercury from aqueous dilute solutions containing chloride ions. The kinetic behavior of the mercuric ion reduction was analyzed and its diffusion coefficient was determined with the use of a rotating disk electrode. Experimental results of the removal of mercury from aqueous sodium chloride solutions containing 100 ppm mercury by contact with iron felt are reported. The mercury concentration was decreased to values lower than 0·1 ppm. The recovery of metallic mercury by chemical attack of the residual iron felt was also analyzed.
Sequential anaerobic–aerobic treatment of sulphur rich phenolic leachates
Authors: Kettunen Riitta H. , Rintala Jukka A.
Published: May 2005

Sequential biological anaerobic–aerobic treatment of oil shale ash dump leachate was studied using laboratory‐scale reactors and bioassays. The COD of the leachate was 2·0–3·0 g dm−3. The leachate was known to contain several phenolic compounds and to have a high sulphur concentration. The proportion of the leachate in the feed of the biological process was gradually increased during a 309 day test period. With 100% leachate in the feed, COD removal was 35% in the anaerobic stage while in the combined process the COD and BOD7 removals were up to 75% and 99%, respectively. The removal of total phenols was insignificant in the anaerobic stage, while up to 85% removal was obtained by the combined anaerobic–aerobic process. In the anaerobic stage, degradation of organic compounds was mainly a result of sulphide production. The results demonstrated that the leachates were amenable to biological treatment.
Targeting the development of membranes for gas separation
Authors: Hinchliffe Anthony B.
Published: May 2005

This paper presents the new concept of ‘Targeting’ the properties of new membrane materials. Cost parameters are defined in terms of effective selectivity and cost permeability. These new parameters, obtained from the analysis of membrane plant suppliers' bids, are used in a procedure which determines the optimal degree of separation and recovery. The use of the targeting methods is illustrated here in the development of new membranes for the separation of CO from an H2/CO syngas for the large‐scale manufacture of acetic acid. The targeting approach can be extended to include other gas separation technologies and will aid the development of a generic methodology for the design of gas separation processes.
Denitrifying kinetics involving the distributed ratio of reductases
Authors: Her Jiunn‐Jye , Huang Ju‐Sheng
Published: May 2005

A suspended‐growth batch reactor was used to denitrify synthetic wastewater containing various proportions of nitrate and nitrite. A competitive phenomenon between nitrate‐ and nitrite‐reductase was studied utilizing various proportions of nitrate and nitrite in an anaerobic environment with a temperature of 30°C and methanol as carbon source.

By using a non‐linear regression technique, biokinetic constants of the maximum specific reduction rates of nitrate and nitrite (k1, k2) and the Monod half‐saturation coefficients of nitrate and nitrite (Ks1, Ks2) for the proposed two‐step denitrifying kinetics were 1·29 day−1, 0·89 day−1 and 14·3 mg NO‐N dm−3, 10.9 mg NO‐N dm−3, respectively. The result obtained from a series of chemostat studies indicated the Monod‐type kinetic model was more accurate when the distributed ratio of nitrate‐ and nitrite‐reductase in the proposed two‐step denitrifying kinetics was taken into account.
Biosorption of heavy metals (Cd, Cu, Ni, Pb, Zn) by chemically‐reinforced biomass of marine algae
Authors: Leusch Andreas , Holan Zdenek R. , Volesky Bohumil
Published: May 2005

Particles of two different sizes (0·105–0·295 mm and 0·84–1.00 mm diameter) of two marine algae, Sargassum fluitans and Ascophyllum nodosum, were crosslinked with formaldehyde (FA), glutaraldehyde (GA) or embedded in polyethylene imine (PEI), followed by glutaraldehyde crosslinking. They were used for equilibrium sorption uptake studies with cadmium, copper, nickel, lead and zinc. The metal uptake by larger particles (0·84–1·00 mm) was higher than that by smaller particles (0·105–0·295 mm). The order of adsorption for S. fluitans biomass particles was Pb > Cd > Cu > Ni > Zn, for A. nodosum copper and cadmium change places. Uptakes of metals range from qmax = 378 mg Pb g−1 for S. fluitans (FA, big particles), to qmax = 89 mg Zn g−1 for S. fluitans (FA, small particles) as the best sorption performance for each metal. Generally, S. fluitans is a better sorbent material for a given metal, size and modification, although there were several exceptions in which metal sorption by A. nodosum was higher. The metal uptake for different chemical modifications showed the order GA > FA > PEI. A comparison of different sorption models revealed that the Langmuir sorption model fitted the experimental data best.
Biodegradation of phenol‐polluted air using an external loop airlift bioreactor
Authors: Ritchie Brian J. , Hill Gordon A.
Published: May 2005

Biological air treatment methods are an alternative to conventional treatment methods such as activated carbon adsorption and chemical scrubbing. An external loop airlift bioreactor has been utilized to treat phenol‐contaminated air using Pseudomonas putida. Saturated air was found to be cleansed of phenol below the detectable limit because of the high mass transfer rate of the pollutant from the air and the high growth rate of Pseudomonas putida. The bioreactor was found to degrade over 99% of the inlet phenol at rates from 21·5 to 194 mg h−1 at concentrations between 650 and 850 mg m−3 of air. A model of the system is developed based on an initial transient period followed by a pseudo‐steady state period. The simulations compared well with the experimental data.
Effect of fluid rheological properties on mass transfer in a bioreactor
Authors: Li Guo‐Qing , Qiu Hong‐Wei , Zheng Zhi‐Ming , Cai Zhao‐Ling , Yang Shou‐Zhi
Published: May 2005

Rheological properties and oxygen mass transfer coefficient (kL a) were investigated in a stirred reactor (10 dm3) in the course of fermentations producing microbial polysaccharides—pullulan and xanthan. The fermentation broths behaved as pseudoplastic non‐Newtonian fluids in both cases. Studies on the relationship between fluid rheological properties and kL a were also carried out. The oxygen mass transfer coefficient decreases during the fermentation and exponential equations have been obtained to describe the relationship between the oxygen mass transfer coefficient, the agitation speed and the apparent viscosity of the broths. Furthermore, comparison of results between pullulan and xanthan fermentations was investigated. For the xanthan fermentation process, mixing and mass transfer in the reactor were more difficult than those for the pullulan fermentation.
Extracellular polymers in activated sludge and stable foams
Authors: Kerley Sarah , Forster Christopher F.
Published: May 2005

The hydrophobicity and surface polymer extracellular polymer characteristics of a range of foams and mixed liquor samples were examined and the species involved studied. The results show that, for samples dominated by Microthrix parvicella, the hydrophobicity of the solids was linearly related to the uronic acid content of the extracellular polymer polysaccharide. The stability of foams was increased significantly with the addition of polyvalent metal ions to the mixed liquors producing the foams.
Enzymatically‐mediated uranium accumulation and uranium recovery using a Citrobacter sp. Immobilised as a biofilm within a plug‐flow reactor
Authors: Macaskie Lynne E. , Empson Ruth M. , Lin Fan , Tolley Mark R.
Published: May 2005

Biofilm‐immobilised Citrobacter sp. removed uranyl ion from flows supplemented with glycerol 2‐phosphate. The metal uptake mechanism was mediated by the activity of a cell‐surface bound phosphatase that precipitated liberated inorganic phosphate with uranyl ion as HUO2PO4·4H2O at the bacterial surface. A modified integrated form of the Michaelis–Menten equation is proposed to describe the removal of metal ion by a columnar bioreactor, where the efficiency of metal removal is semi‐quantitatively related to the input flow rate, the total enzyme loading (E0) and the bioreactor activity. With biofilm‐immobilised bacteria, E0 was further divisible (split) into subparameters of phosphatase titre per bacterium and total biomass surface area. Varying the split E0 and the reaction temperature modified the bioreactor performance. The immobilised bacteria retained high metal loads without loss in steady‐state activity. Accumulated metal was recovered as a concentrated solution.
Preparation and characterisation of the perovskite oxide superconductor YBa2Cu3O7 − x
Authors: Dursun G , Winterbottom J M
Published: May 2005

A perovskite oxide, YBa2Cu3O7 − x (YBCO), has been prepared by the method of carbonate precipitation from a mixed nitrate solution and oxidised at 950°C in an air atmosphere to obtain a perovskite oxide to be used as a catalyst for H2/CO reactions. The characterisation of the perovskite oxide was performed by using X‐ray diffraction before and after the treatment with different gases, A.C. susceptibility measurements, particle size measurements and temperature programmed reduction (TPR) in which hydrogen was used in order to monitor the changes of the perovskite with temperature in a hydrogen atmosphere. A.C. susceptibility measurements showed that the YBCO perovskite exhibited the typical good superconducting sharp transition temperature at 93 K, indicating that the wet chemical preparation route is suited to the production of this material.
Saccharification of modified starch to maltose in a semi‐continuous counter‐current chromatographic reactor–separator (SCCR–S)
Authors: Shieh M. T. , Barker P. E.
Published: May 2005

Combined bioreaction and separation has been successfully carried out in a Simulated Counter‐Current Chromatographic Reactor–Separator (SCCR–S) system for the saccharification of modified starch to maltose and dextrin. The effects of the operating parameters (switch time, eluent flowrate, feed concentration and enzyme activity) on the performance of the SCCR–S system were investigated. By using an eluent of dilute enzyme solution, starch conversions of up to 60% were achieved using lower amounts of enzyme than the theoretical amount required by a conventional bioreactor to produce the same amount of maltose over the same time period. Comparing the SCCR–S system with a continuous rotating annular chromatograph (CRAC) for the saccharification of modified starch showed that the SCCR–S system required only 34·6–47·3% of the amount of enzyme required by the CRAC, system.