bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on the properties of iron–cobalt alumina supported catalyst for ammonia
Authors: Kaleńczuk Ryszard J.
Published: May 2005

The addition of Co to Fe/Al2O3 increases the catalytic activity in NH3 synthesis. The maximum effect is observed for 20% by weight of Co in the metallic phase. Bivalent cobalt atoms replace bivalent iron atoms (a similar ionic radius) in the crystal lattice. This process changes the reducibility of the samples. The Fe‐Co compound and its formation results in the fairly high temperature of reduction (873 K) which is needed to prepare the most active catalyst. Changing the reactor atmosphere from reducing to inert causes the disappearance of free iron (escape of Fe to the crystal lattice of support with formation of a new compound with a spinel character). This is the effect of the iron‐hydrogen interaction. The formation of an intermetallic iron‐cobalt compound is crucial to the catalyst activity. This might be due to the surface restructuring by exposing the most active iron surface, Fe(111). The potassium addition in the form of KOH causes an increase in the catalytic activity. The increase is not as high as for a ‘super basic’ Fe‐Co magnesium hydroxide carbonate supported catalyst studied earlier. A part of the potassium hydroxide is used to neutralize the acid sites on the surface of alumina.
Kinetics of the liquid phase synthesis and hydrolysis of butyl lactate catalysed by cation exchange resin
Authors: Dassy Stephane , Wiame Hughes , Thyrion Fernand C.
Published: May 2005

Esterification of lactic acid with butanol catalysed by cation‐exchange resin was carried out in a batch reactor in dioxane and toluene. The reaction rate was found to be first order with respect to catalyst and acid concentrations. The inhibiting effect of water and butanol has been evaluated. The rate data were correlated with a kinetic model based on inhibition by water and butanol.
Cementitious mixtures containing industrial process wastes suitable for the manufacture of preformed building elements
Authors: Beretka Julius , Cioffi Raffaele , Santoro Luciano , Valenti GianLorenzo
Published: May 2005

Mixtures made from materials containing reactive oxides of calcium, aluminium, sulphur and silicon which are able, upon hydration, to generate calcium trisulphoaluminate and silicate hydrates, have been studied with a view to possible applications in the field of preformed building elements. The materials employed were natural gypsum, phosphogypsum, fly ash, blast furnace slag, Portland cement and hydrated lime. The samples were cured at 55, 70 and 85°C and 100% RH for 24 h, followed by further curing at ordinary temperatures and humidities (21°C, 67% RH) for up to 28 days. The cured samples were tested for compressive strength and shrinkage. It has been found that the most important effect on the strength is due to the pre‐curing temperature, while the post‐curing time has much less effect. In general, the optimum pre‐curing temperature is 70°C. Satisfactory strength results were obtained even with systems containing up to 80% waste materials.
Asymmetric reduction of prochiral ketones by cell‐free systems from alcaligenes eutrophus
Authors: Madyastha Kattigere M. , Gururaja Tarikere L.
Published: May 2005

A strain of Alcaligenes eutrophus has been isolated from the soil by enrichment culture technique with nerolidol (1), a sesquiterpene alcohol, as the sole source of carbon and energy. Fermentation of nerolidol (1) by this bacterium in a mineral salts medium resulted in the formation of two major metabolites, viz. geranylacetone (2) and an optically active alcohol, (S)‐(+)‐geranylacetol (3). Nerolidol (1)‐induced cells readily transformed 1,2‐epoxynerolidol (4) and 1,2‐dihydroxynerolidol (5) into geranylacetone (2). These cells also exhibited their ability to carry out stereospecific reduction of 2 into (S)‐(+)‐geranylacetol (3). Oxygen uptake studies clearly indicated that nerolidol‐induced cells oxidized compounds 2, 3, 4, 5 and ethyleneglycol (7). Based on the nature of the metabolites isolated, the ability of nerolidol‐induced cells to convert compounds 4 and 5 into geranylacetone (2), and oxygen uptake studies, a pathway for the microbial degradation of nerolidol (1) has been proposed. The proposed pathway envisages the epoxidation of the terminal double bond, opening of the epoxide and cleavage between C‐2 and C‐3 in a manner similar to the periodate oxidation of cis‐diol. The cell‐free extract prepared from nerolidol‐induced cells readily carried out the asymmetric reduction of compound 2 to an optically active alcohol (3) in the presence of NAD(P)H. The cell‐free extract carried out both oxidation and reduction reactions at two different pH values and exhibited wide substrate specificity towards various steroids besides terpenes.
New strategies for the Hofmann reaction
Authors: Rane Dhananjay S. , Sharma Man M.
Published: May 2005

Some new strategies, such as the use of hydrotropes, surfactants, co‐solvent, etc., were applied to the Hofmann reaction of fatty amides to obtain isocyanates, amines and carbamates. Additionally, some industrially important aromatic amines were synthesised.
Adsorption of cadmium and zinc from aqueous solution on natural and activated bentonite
Authors: Pradas E. González , Sánchez M. Villafranca , Cruz F. Cantón , Viciana M. Socías , Pérez M. Fernández
Published: May 2005

The adsorption of cadmium and zinc ions on natural bentonite heat‐treated at 110°C or at 200°C and on bentonite acid‐treated with H2SO4 (concentrations: 0·5 mol dm−3 and 2·5 mol dm−3), from aqueous solution at 30°C has been studied. The adsorption isotherms corresponding to cadmium and zinc may be classified respectively as H and L types of the Giles classification which suggests the samples have respectively a high and a medium affinity for cadmium and zinc ions.

The experimental data points have been fitted to the Langmuir equation in order to calcualte the adsorption capacities (Xm) and the apparent equilibrium constants (Ka) of the samples; Xm and Ka values range respectively for 4·11 mg g−1 and 1·90 dm3 g−1 for the sample acid‐treated with 2·5 mol dm−3 H2SO4 [(B)‐A(2·5)] up to 16·50 mg g−1 and 30·67 dm3 g−1 for the natural sample heat‐treated at 200°C [B‐N‐200], for the adsorption process of cadmium, and from 2·39 mg g−1 and 0·07 dm3 g−1, also for B‐A(2·5), up to 4·54 mg g−1 and 0·45 dm3 g−1 [B‐N‐200], for the adsorption process of zinc. Xm and Ka values for the heat‐treated natural samples were higher than those corresponding to the acid‐treated ones. The removal efficiency (R) has also been calculated for every sample; R values ranging respectively from 65·9% and 8·2% [B‐A(2·5)] up to 100% and 19·9% [B‐N‐200], for adsorption of cadmium and zinc.
An on‐line respirographic biosensor for the characterization of load and toxicity of wastewaters
Authors: Vanrolleghem Peter A. , Kong Zaide , Rombouts Guido , Verstraete Willy
Published: May 2005

A respirographic biosensor is presented that is capable of monitoring the waste load and potential toxicity of wastewaters, both off‐line in a laboratory or on‐line at the wastewater treatment plant. The principles of the sensors' operation have been developed and implications of the design choices evaluated. Short term BOD values were obtained every 30 min. The linear dynamic range spanned concentrations differing by a factor of 5000. This range could be expanded by a factor of 10 by adjusting the aeration rate of the bioreactor in the sensor. The response time for toxicity detection was approximately 1 h. The use in the sensor of activated sludge from the plant concerned ensured relevant toxicity information was obtained. To check the condition of the sludge, an independent respiration measurement is proposed. When a siginificant activity change is observed, the sludge in the sensor must be replaced. The presence of oxidoreduction chemicals can cause interferences that may lead to measurement errors. Based on a difference in reaction kinetics, their presence can be assessed and the effect eliminated. Both on‐line and laboratory applications in the chemical industry are presented. Special emphasis is given to the usefulness of the sensor data for waste management of production divisions. On‐line assessment of load variations and hydrogen peroxide spills are given as illustrations of the implementation of the sensor on the treatment plant. Attention is drawn to the potential application of the data for process control and improved performance of the treatment plant.
Purification of nickel sulphate solutions containing iron, copper, cobalt, zinc and manganese
Authors: Senapati Debasis , Chaudhury G. Roy , Sarma P. V. R. Bhaskara
Published: May 2005

Acidic nickel‐bearing solution containing iron, cobalt, manganese, zinc and copper was processed through a solvent extraction and precipitation technique to obtain a pure nickel sulphate solution. Iron was extracted using 0.2M Cyanex‐272 (partially neutralised) as the extractant. Stripping of iron from the loaded organic has also been studied. After iron recovery through solvent extraction the raffinate still contained 0·25 g dm−3 of iron which was quantitatively separated by a lime precipitation technique. During this iron precipitation there was no loss of cobalt and nickel but copper, manganese and zinc were coprecipitated to some extent. From the iron‐free nickel sulphate solution the other impurities were extracted using the same extractant (Cyanex‐272) in a single stage. The metal ions from the loaded organic were stripped using a 0·5% (v/v) H2SO4 solution in a single stage. The entire operation needs only seven stages: two stages for iron extraction, three stages for iron stripping from the loaded organic, and one stage each for extraction and stripping of other impurities. In the entire operation the loss of nickel was less than 0·5%.
Pectinlyase immobilization on polyamides for application in the food processing industry
Authors: Spagna Giovanni , Pifferi Pier G. , Tramontini Maurilio , Albertini Alberto
Published: May 2005

The study concerns the immobilization of a pectinlyase (PL, EC 4.2.2.3) purified by means of a commercial enzyme for its possible applications in fruit juice and beverage processing. Results previously obtained were improved by employing polyamides, i.e. nylon 6 and nylon 11, activated by easy to perform and inexpensive methods such as direct activation with glutaraldehyde and alkylation with dimethylsulphate followed by treatment with amines and glutaraldehyde. The nylon 6 activated with glutaraldehyde gave an activity of the immobilized PL of about 200 U g−1 (at optimum pH) and a half‐life of about 190 h (at pH 3·3 and 25°C).
Kinetics of zinc adsorption on charcoal
Authors: Mishra S. Prabha , Chaudhury G. Roy
Published: May 2005

The kinetics of zinc adsorption on charcoal was carried out. In order to study the kinetics of adsorption various parameters were studied such as pH, particle size of charcoal, temperature, amount of charcoal as well as initial Zn2+ ion concentration. The adsorption kinetics followed a Freundlich adsorption isotherm. Good correlation of the theoretical and experimental equilibrium concentrations of Zn2+ ions was observed for the isotherm model. A mathematical model was developed to explain the kinetic data. The rate determining step for adsorption was found to be diffusion controlled.
Penicillin G extraction from model media using an emulsion liquid membrane: A theoretical model of product decomposition
Authors: Lee Kwi Ho , Lee Sang Cheol , Lee Won Kook
Published: May 2005

To confirm the applicability for the extraction of penicillin G by an emulsion liquid membrane (ELM), the degree of decomposition of penicillin G during extraction was theoretically calculated. Decomposition was less than 1% provided that the initial sodium carbonate concentration in the internal phase was correctly determined, which proved the applicability of the ELM process. The procedure to determine the initial carbonate concentration in the internal phase was also described in order that the pH in the internal phase should be within the relatively stable range for penicillin G at the end of the extraction.
Penicillin G extraction from model media using an emulsion liquid membrane: Determination of optimum extraction conditions
Authors: Lee Kwi Ho , Lee Sang Cheol , Lee Won Kook
Published: May 2005

Penicillin G extraction by an emulsion liquid membrane (ELM) was investigated. The effects of surfactants, diluents, and carrier mixtures, together with their combined effects on the initial extraction rate and the emulsion stability were examined. Surfactants, diluents, and carriers used were Span80 (sorbitan monooleate)/ECA4360J (nonionic polyamine),n‐butyl acetate/kerosene, and DOA (dioctylamine)/Amberlite LA‐2 (secondary amine), respectively. The optimum extraction conditions were found to be 20% (v/v) of Span80 in ECA4360J as a surfactant, kerosene as a diluent and Amberlite LA‐2 as a carrier.
Production, purification and immobilisation of inulinase from Kluyveromyces fragilis
Authors: Gupta Anil K. , Singh Davinder Pal , Kaur Narinder , Singh Rangil
Published: May 2005

Kluyveromyces fragilis (NCIM 3217), Kluyveromyces marxianus (NCIM 3231), Hansenula polymorpha (NCIM 3377), Pichia fermentan (NCIM 3408), Pichia polymorpha (NCIM 3419) and Debaryomyces castellii (NCIM 3446) were grown on an inulin‐based growth medium. Only K. fragilis produced extracellular inulinase with a maximum after 36 h of growth at 25–27°C. Sucrose and fructose were weak inducers of inulinase as compared to inulin whereas with glucose the inulinase level was minimal. An aqueous extract of chicory roots containing 1% fructan was a better carbon source than inulin and peptone was the best nitrogen source for the production of inulinase. The maximum yield of inulinase was about 7 units cm−3 of medium. The invertase to inulinase ratio of 10 in the culture filtrate was reduced to 1·6 on purifying inulinase by ethanol precipitation followed by chromatography on Sephadex G‐200, DEAE‐cellulose and CM‐cellulose columns. Using this purification procedure, inulinase was purified 26‐fold. With inulin as substrate, the shape of the velocity curve was nearer to a sigmoidal pattern whereas with sucrose the curve was hyperbolic. The molecular weight of inulinase was determined as 250 ± 10 kDa. The crude and purified inulinase preparations did not release sucrose or oligosaccharides from inulin, indicating that the enzyme has primarily exo‐inulinase activity. Using the metal‐link chelation method, 40% of inulinase was immobilised on cellulose. Maximum activity of crude, purified and immobilised inulinase preparations was observed at 55°C. The half‐life of immobilised inulinase at 25°C was 5 days.
Enzymatic enantioselective hydrolysis of acyloxyferrocenophanes using lipases and esterases
Authors: Izumi Taeko , Aratani Satoshi
Published: May 2005

Enantioselective hydrolysis of racemic acetate or butyrates of 1‐hydroxy [3](1,1′) ferrocenophane and endo‐1‐hydroxy [4](1,2) ferrocenophane using lipases, pig liver esterase and horse liver esterase resulted in the formation of (R)‐alcohols and (S)‐esters.
Selectivity aspects in the multi‐phase hydrogenation of α,β‐unsaturated aldehydes over supported noble metal catalysts: Part II
Authors: Satagopan V. , Chandalia Sampatraj B.
Published: May 2005

The hydrogenation of cinnamaldehyde to cinnamyl alcohol over a platinum on carbon catalyst could be intensified and made more selective in a two‐phase system using toluene and aqueous alkaline solution. Enhancement in the selectivity with respect to citronellol was noticed in the two‐phase hydrogenation of citronellal, while the reaction rate was marginally affected. Potassium hydroxide and sodium hydroxide were found to be efficient promoters.
Adsorptive recovery of water soluble essential oil components
Authors: Bohra Poonam M. , Vaze Abhay S. , Pangarkar Vishwas G. , Taskar Ajay
Published: May 2005

Many essential oils are produced by the process of steam distillation. During this process valuable oxygenated components of the oil which have relatively higher solubility in water are preferentially lost in the distillate water. This loss is directly reflected in a lower yield and poor quality of the oil. Adsorption is extensively used for recovery of such valuable organics from dilute aqueous streams. This paper describes a preliminary study on the feasibility of adsorptive recovery. The following synthetic polymeric adsorbents were used in this work: Amberlite XAD‐2, XAD‐4 and XAD‐7. Equilibrium and column exahaustion studies were carried out for the adsorption of phenyl ethyl alcohol (PEA), linalool (LL) and eugenol (EG) and also of mixtures of PEA and LL, and EG and LL from dilute aqueous solutions. The results indicate that XAD‐4 is a relatively better adsorbent for all the three solutes studied.
A purification method for specific serine proteases using one‐step affinity chromatography
Authors: Grzywnowicz Krzysztof , Łobarzewski Jerzy
Published: May 2005

A simple affinity chromatography procedure for specific isolation of serine proteases is described. The procedure was tested using enzymes from five microbial and one plant source. Feather keratin, covalently bound to controlled‐pore glass, was the support and magnesium chloride was used in the elution buffers instead of zinc chloride. This enabled one‐step isolation of serine proteases present in the biological materials used. The small (15 cm × 1 cm) controlled‐pore keratin‐glass column allowed high flow rates and protected the proteases from autodigestion during the chromatography process. The serine proteases were eluted from the column with good recovery (40–84·6%) and a purification efficiency between 5 and 7. The purified proteases were homogeneous by polyacrylamide gel electrophoresis.
Removal of metal ions from aqueous solution by activated carbons obtained from different raw materials
Authors: Budinova T. K. , Petrov N. V. , Minkova V. N. , Gergova K. M.
Published: May 2005

The adsorption of Pb2+, Cu2+, Zn2+ and Cd2+ from aqueous solution at 293 K by activated carbons obtained from different raw materials was studied. These carbons were prepared by water vapour pyrolysis of the raw materials—apricot stones, coconut shells and lignite coal. The influence of the solution pH on the adsorption processes has been studied. The presence of other metal ions in the solution decreases the adsorption of each of the ions. The selective adsorption of the metal ions is observed but the ones preferentially adsorbed do not completely prevent the adsorption of other ions. The chemical nature of the carbon surface and metal ions have great significance for the adsorption process.
Construction and performance characteristics of a metformin electrode based on the metformin phosphotungstate ion‐associate
Authors: Shoukry Adel F. , Rizk Mahmoud S. , Abdel‐Fattah Hussein M. , Issa Yousry M. , Atia Ehab M.
Published: May 2005

A new metformin (Mf) ion selective PVC membrane electrode based on the ion‐associate of Mf with phosphotungstic acid was prepared. The electrode exhibited a mean calibration graph slope of 58 mV Mf concentration decade−1, at 25°C, within the concentration range 2·0 × 10−5−1·0 × 10−2 M MfCl. The change of pH within the range 4·0–11·0 did not affect the electrode performance. The standard electrode potentials were determined at different temperatures and used to calculate the isothermal coefficient of the electrode (0.000352 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 applied to determine Mf in pure solutions and in metformin‐containing tablets.
Contaminated and polluted land: A general review of decontamination management and control
Authors: Tadesse Behailu , Donaldson John D. , Grimes Sue M.
Published: May 2005

Although land pollution is a major environmental concern it is probably the least understood source of pollution in terms of both transport of toxins and remediation. This paper deals with the current situation in legislation and land pollution remediation and highlights future requirements.
Commercial synthesis of α‐D‐cellobiosyl bromide heptaacetate
Authors: Goggin Katherine D. , Hammen Philip D. , Kuntson Kimberlee L. , Lambert Jack F. , Walinsky Stanley W. , Watson Harry A.
Published: May 2005

A detailed commercial process for the synthesis and purification of the activated disaccharide, α‐D‐cellobiosyl bromide heptaacetate (1) was developed. Reaction of α‐D‐cellobiose octaacetate (CBO) with HBr in glacial acetic acid or in glacial acetic acid/methylene chloride combination affords α‐D‐cellobiosyl bromide heptaacetate in high yield and excellent quality. Process variables such as reaction solvent, reaction time, reaction temperature, HBr stoichiometry, isolation methods and product purification options were optimized for large‐scale synthesis. α‐D‐Cellobiosyl bromide heptaacetate was successfully prepared in a commercial manufacturing plant.
Solvent extraction of the trivalent lanthanides and yttrium by mixtures of 3,5‐diisopropylsalicylic acid and neutral organophosphorus compounds
Authors: Preston John S. , Du Preez Anna C.
Published: May 2005

Neutral organophosphorus compounds containing a phosphoryl or thiophosphoryl group were found to cause appreciable synergistic shifts in the pH50 values for the extraction of the trivalent lanthanides and yttrium from chloride media by solutions of 3,5‐diisopropylsalicylic acid (DIPSA) in xylene. For the series of compounds with R = n‐butyl, the synergistic effect increases in the order (RO)3PS < (RO)3PO < (RO)2RPO < (RO)R2PO < R3PO. The synergistic effects are greater for lutetium(III) than for lanthanum(III) and, as a result, the separation across the lanthanide series (pH–pH) increases from only 0·17 pH unit for 0·25 M DIPSA alone to, for example, 0·85 pH unit for a mixture of 0·25 M DIPSA and 0·25 M triisobutylphosphine oxide (TIBPO). Mixtures of DIPSA and TIBPO give somewhat better separation factors between the light and middle lanthanide fractions (β = 3·0) than the commercial Versatic 10 acid (β = 2·6), and separation factors comparable to those of the latter extractant between the heaviest lanthanides (thulium to lutetium).
A dynamic model for rectangular capillary suction apparatus
Authors: Lee Duu‐Jong
Published: May 2005

A model for the dynamic behaviour of wet front distance and liquid saturation in rectangular capillary suction apparatus (RCSA) is developed. Governing equations based on the mass/momentum balance are derived and solved numerically. The calculation shows that the effects of the intial conditions on system dynamics vanish rapidly, and the system will then evolve along a slow manifold independent of the initial conditions. When time is large, the dimensionless wet front distance with time is a straight line on a log–log plot with slope 1/2, and the liquid saturation under the inner cell will approach to a constant which depends only on the product of solid concentration and the averaged specific resistance if the RCSA is fixed. Optimum experimental conditions are suggested. A rapid method based on the model for estimating the averaged specific resistance of cake is proposed and compared with experimental findings.
Liquid phase oxidation of 3,4‐dihydroxybenzoic acid and the effect of the products on trihydroxy aluminium precipitation yields
Authors: Whittington Barry I. , Tran Tam , Trimm David L. , Armstrong Lyndon G.
Published: May 2005

Organic compounds are known to interfere with the precipitation of trihydroxy aluminium (gibbsite) in the Bayer process. Studies have been carried out of the effect of 3,4‐dihydroxybenzoic acid on precipitation and of the beneficial effect that can be achieved by oxidising the acid. Measurements of precipitate yields both in the presence of the acid and of products obtained by oxidising the acid were made. Oxidation in the presence of various metal ions was also examined. The yield of precipitate was found to decrease in the order Cu2+ (1·9 mM) > Fe3+ (2·2 mM) > blank (no added organics) > Mn4+ (44·3 and 2·3 mM) > Mn2+ (2·3 mM) > Mn2+ (44·3 mM) ≈ uncatalyset oxidation > Fe3+ (43·5 mM) > Cu2+ (38·2 mM) > untreated sample. This relative ordering was generally unaffected by reaction temperature or oxygen partial pressure. Soluble manganese salts were formed by partial dissolution of MnO2 in the alkaline solutions. These salts were required for oxidation of the 3,4‐dihydroxybenzoic acid to products which, collectively, did not poison the trihydroxy aluminium precipitation process.
Steam and carbon dioxide activation of Eucalyptus globulus charcoal
Authors: Arriagada Renán , García Rafael , Reyes Patricio
Published: May 2005

The partial gasification of Eucalyptus globulus charcoal, using carbon dioxide and steam as activating agents is studied. The influence of some preparation variables such as temperature and reaction time on textural, morphological and acid–base properties are given. The results obtained show that both activating agents produce microporous activated carbons and that a large increase in meso‐ and macroporosity is observed when steam and high burn‐off are used. It has been found that these activated carbons have weak acid sites and the effect of the burn‐off on the acid strength depends on the activating agent. Thus, the acid strength of these sites decreases with the burn‐off when steam is used, but no effect is observed when carbon dioxide is used.
The role of acetyl chloride in the chlorination of acetic acid
Authors: Mäki‐Arvela Päivi , Paatero Erkki , Salmi Tapio
Published: May 2005

The role of acetyl chloride as the active catalyst in the chlorination of acetic acid to mono‐ and dichloroacetic acids was examined by chlorinating acetic acid and monochloroacetic acid in the presence of acetyl chloride in semibatch and batch reactors. The reaction kinetics was autocatalytic when the acetyl chloride concentration was maintained constant by addition. If the acetyl chloride was added only at the beginning of the experiment the reaction rate decreased owing to the volatilization of acetyl chloride. The volatilization increased at high acetic acid conversions, since the solubility of acetyl chloride is lower in monochloroacetic acid than in acetic acid. The chlorination kinetics was described by a reaction mechanism consisting of acid‐catalysed acetyl chloride enolization followed by enol chlorination and chlorine exchange steps. According to the mechanism the enol chlorination proceeds in parallel to the formation of mono‐ and dichloroacetyl chlorides. This was verified in separate experiments, in which acetyl chloride was chlorinated in the presence and in the absence of an acidic enolizing agent, chlorosulphonic acid. The chlorine exchange reactions were verified by studying the acetyl chloride–monochloroacetic acid and the acetyl chloride–dichloroacetic acid equilibria. Chlorination of monochloroacetic acid in the presence of acetyl chloride revealed that dichloroacetic acid is formed mainly via the chlorination of acetyl chloride to dichloroacetyl chloride, which undergoes chlorine exchange with monochloroacetic acid.
New plastic membrane ion‐selective electrode for determination of trimethoprim
Authors: Aboudan Mahmoud , Issa Yousry M. , Shoukry Adel F.
Published: May 2005

Trimethoprimium‐phosphomolybdata, (TM)3PM, was used as an ion‐exchanger in the construction of a TM‐responsive plastic membrane electrode. The calibration graph slope of the electrode is 56·5 mV per TM concentration decade when preconditioned by soaking in water, over a concentration range of 2·3 × 10−6–10−2 M with instantaneous response. The electrode has a life span of 24 h when soaked in 10−3 M TM solution and 5 days when soaked in distilled water. The working pH and temperature ranges of the electrode are 1·6–6·2 and 30–65·C, respectively. The isothermal coefficient of the electrode is 0·00091 V·C−1. The electrode is highly selective for TM towards inorganic cations, sugars and amino acids. It can be employed as a potentiometric sensor for determination of TM in pure solution and in tables.
Liquid‐phase mixing in external‐loop airlift bioreactors
Authors: Kawase Yoshinori , Omori Naoki , Tsujimura Masanari
Published: May 2005

Mixing time, circulation time and downcomer linear liquid velocity were measured in two sizes of external‐loop airlift bioreactors with Newtonian and non‐Newtonian fluids.

The mixing time increased as a result of an increase of non‐Newtonian characteristics. However, the liquid circulation time was affected only slightly by non‐Newtonian flow behaviour. A semi‐empirical correlation for circulation time in external‐loop airlift bioreactors was proposed. The proposed correlation was compared with the present experimental results and those in the literature. Reasonable agreement was obtained between the predicted and experimental values of circulation times.

The downcomer liquid velocity was almost independent of the downcomer‐to‐rise cross‐sectional area ratio. The correlation based on the concept of an eddy diffusivity predicted downcomer liquid velocities in Newtonian and non‐Newtonian fluids.
Kinetics of the catalysed decomposition of N2H by the ceramic superconductor YBa2Cu3O7–δ
Authors: Khalil Laila B. , Mourad Wedad E. , Rophael Magdy W.
Published: May 2005

Evidence of the catalysed decomposition of N2H4 and its salts by a Y–Ba–Cu–O superconductor is presented. A thermostated aqueous suspension of the superconductor, treated with a solution of N2HCl−, produced nitrogen and hydrogen gases, whose volumes were measured at intervals in a gas burette. Two simultaneous reactions are suggested for the reaction between the N2H solution and Y–Ba–Cu–O. One is the reduction of Cu3+ ions in Y–Ba–Cu–O to Cu2+, producing nitrogen, and the other is the catalysed decomposition of N2H by Cu2+ ions in Y–Ba–Cu–O, producing nitrogen and hydrogen. The rates of hydrogen evolution at different initial concentrations of N2H are given. First‐order kinetics at the initial stages of the N2H/Y–Ba–Cu–O reaction were obtained. A comparison between the total nitrogen and hydrogen gases liberated from the reaction shows that the reduction reaction goes faster than the catalysed one. The rate of the catalysed reaction is increased as the initial concentration of the N2H solution increases.
Synergistic effects in the solvent extraction of some divalent metals by mixtures of versatic 10 acid and pyridinecarboxylate esters
Authors: Preston John S. , du Preez Anna C.
Published: May 2005

Pyridinecarboxylate esters were found to cause appreciable synergistic shifts in the pH50 values for the extraction of some divalent base metals by solutions of Versatic 10 acid in xylene. For n‐octyl 3‐pyridinecarboxylate, the synergistic shifts decreased in the order Ni > Co > Cd > Cu ≈ Fe > Mn > Zn, and for the commercial extractant Acorga DS5443A in the order Ni > Cu > Co > Fe > Cd > Mn > Zn. No synergistic effects were observed for divalent lead, calcium and magnesium. On the basis of the pH50 values obtained, several possible practical metal separations are suggested. No loss of metal‐loading capacity was found when the organic phases were contacted with 1 M sulphuric acid for prolonged periods at 30°C.

The effect of changes in the structure of a series of isomeric octyl pyridinecarboxylates is reported for one of the smaller cations studied (copper), as well as for one of the larger cations (cadmium).
The synthesis of sucrose esters from telomer monocarboxylic acids
Authors: Donnelly Michael J. , Bu'Lock John D.
Published: May 2005

Glycolipid biosurfactants possess excellent surfactant properties and can be useful model compounds for the synthesis of surfactants from materials available in large quantities. The incorporation of a long, branched alkyl group, which is a feature of glycolipids, into a synthetic surfactant was achieved by the transesterification of sucrose with the methyl ester of a selected telomer monocarboxylic acid mixture, in a solution reaction. Characterisation showed the product to be a mixture of mono‐ and diesters each comprising a different ratio of linear to branched alkyl chains in the substituted group. Surfactant properties of the mixture, and the chromatographically‐separated components, when evaluated in both distilled water and a salt solution, were found to be superior to a range of sucrose stearates. In addition the biosurfactant analogues were found to be more effective than surfactants derived from β‐keto alkyl esters of various sugars (including sucrose) but were not as efficient as these latter compounds.
Holdup measurements in a Scheibel column by means of an ultrasonic technique
Authors: Bonnet Julio C. , Sorrentino José A.
Published: May 2005

An ultrasonic technique developed by Bonnet and Tavlarides for dispersed phase holdup determination in liquid–liquid contactors has been applied in a 0·10 m diameter Scheibel extraction column. The column consists of three alternate mixing and packing sections of 0·03 and 0·055 m in height, respectively. The packings were built with polypropylene mesh with 96% voidage. The liquid–liquid systems were toluene (dispersed)/water (continuous) and MIBK (dispersed)/water (continuous); the Rushton‐type impellers were operated at 400, 500 and 600 rpm, and with four dispersed and continuous phase flow rates. In one of the mixing chambers two different holdup measuring devices were installed: two ultrasonic transducers and one controlled dispersion sampler. The values of dispersed phase holdup obtained by both methods were compared using statistical methods. It was found that at low agitation and for high interfacial tension, conditions for which the dispersion is not completely uniform, the difference was significant, whereas at high agitation and low interfacial tension the values obtained through both methods were statistically equal. This work demonstrates the applicability of the ultrasonic technique for holdup measurements to Scheibel columns, in which the only technique used so far was sampling. This ultrasonic technique allows us to solve the axial monitoring and control problems of these columns.
Liquid–liquid extraction of a recombinant protein with reverse micelles
Authors: Pires Mario J. , Cabral Joaquim M. S.
Published: May 2005

Recombinant cytochrome b5 was extracted into the reversed micelle phase of an anionic surfactant (AOT) in octane and back‐extracted to a final aqueous phase. The extraction of the protein was controlled by an electrostatic mechanism, since it was dependent on the global charge of the protein. This was directly demonstrated by experiments with native and mutant cytochromes obtained by site directed mutagenesis. The back‐extraction of cytochrome b5 to a fresh aqueous phase was decreased by factors that reduced the size of the water pool of the organic phase, such as high salt concentrations (1–2 mol dm−3 NaCl) and low temperatures (4°C), probably because of an increase in a favourable interaction of this protein with the surfactant at closer distances.
Rate evolution of benzonitrile nitration under heterogeneous conditions
Authors: Andreozzi Roberto , Aquila Tullia , Caprio Vincenzo , Insola Amedeo
Published: May 2005

The development of the nitration process in heterogeneous mixtures of benzonitrile and mixed acids of different compositions is followed in a batch stirred isothermal reactor. Preliminary evaluation of the distribution of the chemical species between the organic and acid phases allows mathematical modelling of benzonitrile nitration under heterogeneous conditions to be achieved on the basis of the previously assessed homogeneous nitration kinetics.
Microbiological treatment of fertilizer solid waste material containing phenoxyalkanoic herbicides 2,4‐D and MCPP
Authors: Oh Kye‐Heon , Tuovinen Olli H.
Published: May 2005

The purpose of the work was to evaluate the feasibility of a biological treatment process for herbicide‐containing solid waste material from a fertilizer‐manufacturing plant. The waste contained approximately 1·5% (w/w) 2,4‐dichlorophenoxyacetate (2,4‐D) and 1·4% (w/w) 2‐(2‐methyl‐4‐chlorophenoxy)propionate (MCPP, mecoprop). Both herbicides could be dissolved from the bulk matrix (vermiculite) within 3 days of chemical leaching in aqueous solution. Upon subsequent inoculation of herbicide‐degrading bacterial consortia derived from soil samples adjacent to the plant, 2,4‐D was completely degraded in the presence of up to 5% (w/v) pulp densities. The biodegradation of MCPP was concurrent but incomplete. The degradation process was acid‐producing, and pH control enhanced the rates of herbicide degradation.
Electrochemical reduction of carbon dioxide and the effect of the enzyme carbonic anhydrase 11 on iron corrosion
Authors: Zvauya Remigio , Dawson John L.
Published: May 2005

The corrosion of pure iron in carbon dioxide saturated solutions at low temperatures has been investigated in this study. Both dc polarisation and ac impedance techniques were used in conjunction with a rotating disc electrode to investigate the reaction sequence leading to hydrogen evolution at 30°C. The results indicate that protons from the low pH solution, the bicarbonate ion and the undissociated carbonic acid molecule contribute to the reaction sequence leading to eventual hydrogen evolution. The corrosion mechanism involves both activation and diffusion processes. A rotating disc electrode in combination with ac techniques and the enzyme carbonic anhydrate II, EC 4.2.1.1, were used to characterise the diffusion effects. A chemical–electrochemical cathodic reaction mechanism is proposed.
Liquid phase oxidation of α‐pinene. Influence of sodium hydroxide as additive
Authors: Encinar José M. , Beltrán Fernando J. , Frades Jesús M.
Published: May 2005

The liquid phase oxidation of α‐pinene in the presence of sodium hydroxide has been studied. Sodium hydroxide exerts an inhibitor effect on the oxidation rate of α‐pinene but selectivity of the main reaction products, verbenol and verbenone, is increased. A temperature between 90 and 100°C results in the highest selectivity values. The kinetics of α‐pinene oxidation and formation of verbenol and verbenone have also been studied and a free radical mechanism proposed.
Kinetics and mechanism of homogeneous catalytic hydroxylation of maleic acid by hydrogen peroxide. Part III: Hydrolysis of cis‐epoxysuccinic acid with sodium tungstate
Authors: Bukowski Wiktor , Litvintsev Igor Yu. , Sapunov Valentin N.
Published: May 2005

The kinetics of catalytic and non‐catalytic hydrolysis of cis‐epoxysuccinic acid (H2E) to tartaric acid (H2T) have been studied. The hydrolysis proceeded much faster in the presence of sodium tungstate catalyst than with an acid or without any catalyst. The results indicated the formation of complexes {cat · H2E} between sodium tungstate (cat) and cis‐epoxysuccinic acid, presumably in the form of tunstenglycolate of tartaric acid. The reaction has been found to be retarded by tartaric acid or, rather, by its complex with catalyst in the form {cat · 2H2T}. A mathematical model of the overall process has been developed and the mechanism of reaction discussed.
Kinetics and mechanism of homogeneous catalytic hydroxylation of maleic acid by hydrogen peroxide. Part IV: Hydrolysis of cis‐epoxysuccinic acid in the presence of ferric ions
Authors: Bukowski Wiktor , Litvintsev Igor Yu. , Sapunov Valentin N.
Published: May 2005

The kinetics of catalytic and non‐catalytic hydrolysis of cis‐epoxysuccinic acid have been studied. The hydrolysis leading to tartaric acid has been found to proceed much faster in the presence of iron (III) catalyst than the reaction without a catalyst or with tungstate catalyst. A complex of the form {cat · H2E} between iron(III) salts (catalyst) and epoxysuccinic acid seems to be responsible for the main catalytic effect. On the other hand, the reaction has been found to be retarded by the product of hydrolysis, tartaric acid (H2T). The inhibiting effect was caused by the formation of a catalyst deactivating complex in the forms {cat · H2T} and {cat · 2H2T}. A mathematical model for the overall process has been developed and the mechanism of reaction discussed.
Synthesis of heterocyclic metal complexes and their evaluation as marine antifoulants
Authors: Osman Maher M. , El‐Malek Mounir M. Abd , Tadros Aida B. , Michael Atef M.
Published: May 2005

4‐Amino‐3‐thio‐1,24‐triazolidine (L1) and 4‐amino‐5‐thio‐1,3,4‐thiadiazole (LII) as well as their metal complexes of the general formulae MLI·2H2O and MLIICl (M; Pb(II), Cd(II) and Zn(II)) were prepared. With Sn(II), we obtained Sn(LI)2·2H2O and SnLIICl, respectively. The structures of the compounds were identified through elemental analysis, and IR and UV spectra measurements, in addition to thermal analysis in case of the metal complexes. The antifouling properties of the compounds were tested by their incorporation into paint formulations which were applied to PVC substrates and tested in water from Alexandria western harbour. When the compounds were added at 17·5% by volume, the coated panels were fouled after 3 months of immersion. The addition of 6·7% by volume of tributyltin oxide to 15·8% of the prepared compounds in one formulation elevated the paint efficiency and prevented fouling for 11 months. Paint containing solely tributyltin oxide at the same concentration was inactive against algae.
Enhancement of biomass and pigment production during growth of Spirulina platensis in mixotrophic culture
Authors: Marquez Facundo J. , Nishio Naomichi , Nagai Shiro , Sasaki Ken
Published: May 2005

Spirulina platensis grew mixotrophically on glucose in the light, ehancing biomass and pigment production. Under light‐limited conditions, biomass production was enhanced by supplemental microbial synthesis from heterotrophic metabolism of glucose. Biomass and photosynthetic pigment production were increased 1·5–2·0‐fold compared with those in autotrophic growth.
Azo disperse dyes for synthetic fibres. 3: 2‐Styrylquinazolone derivatives
Authors: Fadda A. A. , Etman H. A. , Amer F. A. , Barghout M. , Samir Kh. M.
Published: May 2005

Fifteen variously substituted derivatives (IVa–o) of 2‐styrylquinazolone have been prepared for use as dye‐stuffs. The effects of the nature and orientation of substituents on the colour and dyeing properties of these dyes on polyester and acrylic fibres were assessed.
Formulation and optimization of two culture media for the production of tumour necrosis factor‐β in Escherichia coli
Authors: Mak Kenneth W. Y. , Yap Miranda G. S. , Teo Wah Koon
Published: May 2005

Two culture media were designed and optimized by statistical techniques for the growth of Escherichia coli K12 HB101 (pCG402) which expressed human tumour necrosis factor‐β (TNF‐β). Common compounds, such as MgSO4 and KH2PO4, were used to provide the bacteria with the necessary elements for biomass synthesis. For compounds not required for biomass synthesis, such as thiamine, or compounds used for both biomass synthesis and as an energy source, such as glucose, yield coefficients were used. In formulating the composition of the nutrients, carbon was chosen as the limiting substrate in both media. In the complex medium (CM), casein hydrolysate was selected to supply the two auxotrophic amino acids, proline and leucine. The optimal ratio of glucose to casein hydrolysate was determined to be 1:0·6 by using a centre composite design experiment. In the defined medium (DM), the concentrations of the three carbon sources, glucose, proline and leucine were based on their respective yield coefficients (Ybiomass/glucose: 0·5, Ybiomass/proline: 7, Ybiomass/leucine: 13·5). Shake flask experiments based on a fractional design were used to confirm that the two media were glucose limiting. Bacterial growth was improved in CM whereas DM gave higher TNF‐β expression. A 2‐dm3 fed‐batch fermentation using CM was performed and a dry biomass concentration of 20 g dm−3 was obtained with the expression of soluble TNF‐β being 20 mg g−1 dry biomass. With this fed‐batch system, a high biomass concentration and high expression of TNF‐β were achieved concomitantly.
Characterization of extracted complexes in liquid–liquid extraction of rhodium with Kelex 100 in the presence of SnCl2
Authors: Benguerel Elyse , Demopoulos George , Cote Gérard , Bauer Denise , Lautié Alain
Published: May 2005

Mixed RhSn complexes found in aqueous and organic solutions involved in the liquid–liquid extraction of Rh(III) from chloride solutions, also containing SnCl2, with 7‐(4‐ethyl‐1‐methyloctyl)‐8‐hydroxyquinoline (Kelex 100) were characterized through 119Sn NMR and Raman spectroscopy. At Sn: Rh molar ratios of 3:1 and 12:1, it was found that [RhIIICl3(SnCl3)3]3− and [RhI(SnCl3)5]4−, respectively, are the dominant complexes in both the aqueous and organic solutions. These complexes can be quantitatively extracted from the aqueous solutions in less than 1 min contact time via ion‐pair formation with the protonated 7‐substituted 8‐hydroxyquinoline reagent such that for both Sn:Rh ratios, the same RhSn complex is found in the aqueous feed and in the fully loaded organic. In addition, it was found that [RhI(SnCl3)5]4− is preferentially extracted over excess free Sn(II). Preliminary characterization of the complex stripped from the 12:1 loaded organic using 1·7 M H2SO4 shows an RhSn complex having a ratio of 5:1 Sn:Rh.
Color removal from dye wastewaters by adsorption using powdered activated carbon: Mass transfer studies
Authors: Yeh Ruth Yu‐Li , Thomas Adrian
Published: May 2005

Color removal from synthetic dye wastewater which typically emanates from the Taiwan textile industry has been studied using powdered activated carbon (PAC) as an adsorbent. The CIE colorimetric system has been used in the measurement of color for the treatment of disperse‐red‐60 dye wastewater. The effect of contact time, dye concentrations and PAC dosage on color and color removal has been investigated. A film‐pore double resistance diffusion model for mass transfer has also been used in this study to determine the effective diffusivity, Deff, for the adsorption of disperse‐red‐60 dye wastewater to PAC.
A comparative study of the internal architecture of anaerobic granular sludges
Authors: Quarmby Joanne , Forster Christopher F.
Published: May 2005

A range of granular sludges was taken from industrial anaerobic sludge blanket reactors treating a wide variety of wastewaters and a comparison was made between their surface and internal structures. Scanning electron microscopy showed a similar surface structure of heterogeneous bacteria, regardless of the type of wastewater being treated. However, a study of the internal structure, using sequential staining of ultra‐thin sections, showed the complexity of granular sludges. The majority of the internally‐located bacteria had a morphology similar to Methanothrix. Much of the area was occupied by Gram‐negative organisms and the area which stained positive for protein was found to increase nearer the centre of the granules. This was accompanied by a decrease in the carbohydrate‐positive areas. Positive areas for lipid were widespread throughout the granules. Changes in the internal structure were observed when the type of wastewater treated by the granules was changed and a comparison between sludges treating the same type of wastewater showed that other factors, such as organic loading rate, pH and chemical oxygen demand may also affect the structure of the granules.