bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetic study of an enzymatic liquid—liquid reaction: The hydrolysis of tributyrin by Candida cylindracea lipase
Authors: Martinez Oswaldo , Wilhelm Anne‐Marie , Riba Jean‐Pierre
Published: July 2010

The objective of the work was to derive a kinetic model for the enzymatic hydrolysis of oils. The model reaction examined was the lipolysis of tributyrin by Candida cylindracea lipase. The kinetic model of Verger et al14 was adapted to the particular case of a standard, mechanically‐stirred tank in order to derive the reaction rate as a function of the variables ø, volume fraction of dispersed phase and N, speed of agitation. The validity of a literature correlation relating the mean drop diameter to ø, N and the interfacial tension was verified experimentally. The kinetic relationship was validated by a Lineweaver—Burk representation of the initial reaction rates determined and the kinetic constants were identified. For the system examined, the influence of stirrer speed was weak and limited to low values of ø (ø < 10%).
Solid aromatic products in methanol conversion to hydrocarbons
Authors: Sedran Ulises A. , Fígoli Nora S.
Published: July 2010

The influence of operative parameters on the formation of solid products in methanol conversion to hydrocarbons over amorphous silica—alumina catalysts was studied. Temperature was changed in the 330–430°C range and W/F ratios covered up to 4.65 h. The solid compounds identified were methyl‐substituted aromatics: 1,2,4,5‐tetramethylbenzene, pentamethylbenzene and hexa‐methylbenzene, the last two being the most important ones. Solid products normally represented around 30–40% of the total amount of aromatics formed. Essentially the same behaviour was observed on a zeolitic FCC catalyst.
Flow injection analysis with immobilized enzymes for process control of pullulan production by fermentation
Authors: Englbrecht Ursula , Schmidt Hanns‐Ludwig
Published: July 2010

A flow injection system is described for the parallel determination of pullulan and glucose during a fermentation of the fungus Aureobasidium pullulans. The polysaccharide was hydrolyzed by pullulanase and amyloglucosidase, immobilized to controlled‐pore glass (CPG). The glucose produced was oxidized by glucose dehydrogenase and the NADH formed determined photometrically. The pullulan concentration was calculated from the difference to the response obtained for free glucose. The calibration curves for monomer and polymer were both linear between 2 mg dm−3 and 20 mg dm−3. Analysis of one sample for the determination of glucose and pullulan took about 10 min.
Reactive extraction of lactic acid with Alamine 336 in the presence of salts and lactose
Authors: San‐Martín Marta , Pazos Carmen , Coca Jose
Published: July 2010

The reactive liquid‐liquid extraction of lactic acid with Alamine 336 dissolved in toluene from aqueous solutions of 40.0 g dm−3 lactic acid was examined. Experiments were performed at 25 and 50°C for two amine concentrations of 20% and 40% v/v in toluene, and distribution coefficients were determined. Calculations based on the stoichiometry of the reactive extraction and the equilibria involved indicated that more lactic acid is transferred to the organic phase than would be expected from the stoichiometry of the reaction.

The influence of salts and lactose on the lactic acid extraction was also investigated. Experiments were carried out at 25°C using, as aqueous phases, solutions of lactic acid (40.0 g dm−3) which contained sodium chloride and/or lactose at different concentrations. Results indicated that the extraction of lactic acid with Alamine 336 dissolved in toluene is not affected by lactose. If sodium chloride is present, less lactic acid is extracted by the organic phase and hydrochloric acid co‐extraction is observed.
On the permeation rate of copper extraction through liquid membranes
Authors: Shiau Ching‐Yeh
Published: July 2010

The understanding of the permeation rate of metal ions through liquid membranes is important for the design of such systems. In this paper, the permeation rates of copper ions through liquid surfactant membranes, including interfacial reaction rates and the diffusion rate of the copper ion, were analyzed using a model based on a mobilized hollow spherical globule configuration. The analysis shows that the extracting reaction is dominant at the external interface of the membrane and the stripping reaction is dominant at the internal interface; this means the reactions at both interfaces are not in equilibrium during the course of extraction. It also shows that the extraction rate, the diffusion rate and the stripping rate are not of equal value, especially at the early stage of the run.
Anaerobic treatment of leachates in UASB reactors
Authors: Berrueta José , Castrillón Leonor
Published: July 2010

Leachates from the solid urban wastes landfill of Asturias were characterized and treated in upflow anaerobic sludge blanket laboratory reactors. The highest percentage of COD removal was 88% for a hydraulic retention time of 2–4 days. Gas production was close to the theoretical values, with CH4 content up to 88%. HCl was needed to keep pH neutral, and phosphate was added as nutrient. There was a refractory fraction to the biodegradation of 7%.
Spectrophotometric studies and analytical application of gold(III), yttrium(III) and palladium(II) chelates with 7‐(2‐pyridylazo)‐5‐chloro‐8‐hydroxyquinoline
Authors: Zuhri Ali Z. Abu , Rady Adel H.
Published: July 2010

A spectrophotometric study of Au(III), Y(III) and Pd(II) complexes of a reagent 7‐(2‐pyridylazo)‐5‐chloro‐8‐hydroxyquinoline (PACHQ) is presented. Gold(III) forms a 2:1 (L:M) violet complex at pH 9.5 (50% ethanol), while Y(III) and Pd(II) form 2:1 (L:M) red complexes at pH 6.5 and 7.5 respectively. The stability of these complexes has been determined. Beer's law is valid over the concentration range 0‐7.87, 0‐8.89 and 0‐10.64μg ml−1 for Au(III), Y(III) and Pd(II) respectively. A number of foreign ions were tested for their interference. Synthetic solutions identical in composition to some Au(III) and Y(III) alloys are used to ascertain the suitability of the reagent.
Simultaneous saccharification and isomerization by immobilized glucoamylase and glucose isomerase
Authors: Hui Zhou , Wei Kong , Xiao Cha , Wei Li , Jiacong Shen
Published: July 2010

Glucoamylase (GA) and glucose isomerase (GI), which are often used in industry to produce high‐fructose corn syrup, were immobilized on porous anilinosulphonic polystyrene beads and porous triethanolamine methyl polystyrene beads, respectively. The effects of the amounts of charged groups, the porosity of the carrier and the buffer concentration on the pH profile of immobilized glucose isomerase (IGI) were studied. The apparent pH optimum of the IGI shifted from pH 8.5 to pH 7.3, hence it is possible to carry out simultaneous saccharification and isomerization in a tubular reactor using immobilized glucoamylase (IGA) and IGI. This process is very difficult to accomplish using soluble GA and GI because of the large difference in the pH optima of the two enzymes.
Continuous aqueous phase extraction of proteins: Automated processing and recycling of process chemicals
Authors: Papamichael N. , Börner B. , Hustedt H.
Published: July 2010

A two‐stage aqueous phase extraction of the enzyme fumarase from baker's yeast is described with respect to the recycling of the upper effluent phase from the secondary extraction. It was found that the binodal curve position was only slightly altered by the presence of protein at different load levels and that enzyme specific activity in the product was improved at higher total protein concentrations, which simplified the recycling strategy. On‐line enzyme and protein assays showed that disturbances during start‐up and desludging operations were reflected in variations in the protein concentrations in the various streams, but that the enzyme activities remained relatively stable. Recycling reduced the polyethylene requirements by 50% and that for potassium phosphate by 12%. A maximum saving of PEG (polyethylene glycol) of approximately 70% was achieved at optimum conditions of extraction, compared to a value of 90% predicted by a theoretical description of the system. An economic analysis of the recycled process showed significant advantages compared with a non‐recycled system, even though the capital outlay requirements for an automated, continuous system are much higher than for a manually run process.
Effects of substrate concentration on growth and lactic acid production by mixed cultures of Lactobacillus bulgaricus and Streptococcus thermophilus
Authors: Özen Sevgi , Özilgen Mustafa
Published: July 2010

The kinetics of growth and lactic acid production by mixed cultures of Lactobacillus bulgaricus and Streptococcus thermophilus were modeled with a set of modified logistic and Luedeking‐Piret equations. The specific growth rates and the inhibitory effect of each individual species on the mixed culture growth were found to be determined by the media composition. The kinetic analysis clearly showed that the contribution of each microbial species to the mixed culture growth process changed drastically when the substrate concentration was about 15%. This optimum initial substrate concentration was in agreement with the results of the previous studies and the optimum found by trial and error procedure in commercial yogurt production.
Modelling of the extraction equilibrium of zinc from chloride solutions with tri‐n‐octylphosphine oxide
Authors: Juang Ruey‐Shin
Published: July 2010

The extraction of zinc from chloride solutions with tri‐n‐octylphosphine oxide (TOPO) dissolved in benzene has been thermodynamically studied based on the law of mass action. A model employing the simplified Pitzer equations for stoichiometric activity coefficient estimations is found to be effective for the explanation and prediction of the distribution data, and the thermodynamic extraction constant is determined as log Ket = 5.16 ± 0.11 at 20°C.
Water‐soluble acrylamide copolymers: V. Dispersion properties of poly(acrylamide‐co‐p‐maleimidobenzoic acid) and poly(acrylamide‐co‐sodium N,N‐diallylsulfanilate)
Authors: Hocking Martin B. , Syme David T. , Axelson David E.
Published: July 2010

Eight new poly(acrylamide‐co‐p‐maleimidobenzoic acid) (PAMMBA) water‐soluble copolymers, 3, have been prepared in a synthetic study with the objective to determine the influence of ring incorporation on the surface activity of these materials.1 Sufficient sample was obtained from three of these experiments to enable measurement of the dispersion properties of these polymers using aqueous kaolinite suspensions.

PAMMBA‐1, ‐2, and ‐3 copolymers containing 7, 13, and 23 mole percent p‐maleimidobenzoic acid (MBA) were tested. Their effectiveness as dispersants increased with increasing MBA content. But the copolymer containing 23% MBA required a dose rate four to eight times that of DISPEX N‐40, a commercial dispersant, to obtain equivalent dispersion properties from a standard kaolinite suspension.

In similar copolymer synthesis experiments, ten new poly(acrylamide‐co‐sodium N,N‐diallylsulfanilate) (PAMDAS) copolymers were also prepared and fully characterized.2 Sufficient material was isolated from three of these preparations to enable testing of the dispersant activity.

PAMDAS‐1, ‐2, ‐3 copolymers contained 3·0, 8·4, and 19·2 mole percent sodium N,N‐diallysulfanilate (DAS) and were tested as dispersants in experiments conducted so as to produce results comparable to those of both the PAMMBA copolymers and a commercial dispersant. Dispersant effectiveness increased with increasing DAS content. PAMDAS‐1 (3·0% DAS) was about the same effectiveness as PAMMBA‐1 (7% MBA), PAMDAS‐2 (8·4% DAS) was more effective than PAMMBA‐2 (13% MBA), and PAMDAS‐3 (19·2% DAS) was about equivalent in effectiveness to PAMBA‐3 (23% MBA). Relative to DISPEX N‐40, however, PAMDAS‐2, at a dose rate of 2000 ppm by weight was about half as effective as DISPEX N‐40 at a 250 ppm dose rate.
Stabilization of NAD+‐dependent dehydrogenases and diaphorase by bilayer encagement
Authors: Lehn Christine , Freeman Amihay , Schuhmann Wolfgang , Schmidt Hanns‐Ludwig
Published: July 2010

A feasibility study aimed at stabilization of L‐lactate‐dehydrogenase, L‐malate‐dehydrogenase, alcohol‐dehydrogenase and diaphorase by the recently described method of enzyme ‘encagement’ was conducted. This method involves derivatizing the enzymes with polyglutaraldehyde, followed by secondary crosslinking with amino derivatives of polyacrylamide. Encagement conditions were optimized for each of the four enzymes, so as to achieve the highest thermal stability combined with highest catalytic activity. Depending on the encagement conditions, residual activities were in the range of 18% to 96% with higher values in the presence of cofactors. Increases in thermal stabilization of up to 26‐fold were obtained. For high retention of enzymic activity and stability, the most significant factor was the concentration of polyglutaraldehyde; the crosslinking polymers had only a negligible effect. Furthermore, the significant enhancement in thermal stability could be attained without perturbing the kinetic parameters: Km values for NADH and pH optima remained unaltered for the stabilized enzymes.
Solubilisation of water in alkanes using nonionic surfactants
Authors: Aveyard Robert , Binks Bernard P. , Fletcher Paul D. I. , Ye Xilin
Published: July 2010

Nonionic surfactants are frequently used as emulsifiers in nonpolar oil + water systems and as solubilisation agents for oil in water, or vice versa. In the latter application the amount of, say, water that can be solubilised in nonpolar oil (to give microemulsion droplets) depends on: (a) the capacity of the micelles to incorporate water; and (b) the fraction of surfactant originally present as micelles. This paper is concerned with the single‐phase water‐in‐oil (W/O) microemulsion regions enclosed by the haze and solubilisation boundaries at the oil‐rich end of Shinoda‐type phase diagrams. The systems studied contain the nonionic surfactant C12H25(OCH2CH2)5OH (C12E5), normal alkane (heptane, decane or tetradecane) and water. Critical microemulsion concentrations (cμc) and droplet compositions for w/o microemulsions formed from C12E5 in alkane have been determined at phase boundaries over a range of temperatures. The results show how the maximum extent of water solubilisation is determined jointly by the cμc and the maximum droplet size for a given temperature. It appears that for larger (microemulsion) droplets, the cμc is determined by temperature rather than by droplet size. However, along part of the haze curves, aggregates form with only small amounts of water (less than four molecules per ethyleneoxy group on the surfactant head groups). For a given temperature, in the small range where either micelles or microemulsion droplets can exist, reverse hydrated micelles have much higher critical micelle concentrations (cmc) than the cμc of the larger microemulsion droplets.
Mathematical modelling and simulation of a recycle dialysis membrane reactor in a reversed micellar system
Authors: Chiang Chen‐Li , Tsai Shau‐Wei
Published: July 2010

A mathematical framework was developed for the evaluation of a recycle dialysis membrane reactor (RDMR). The lipase‐catalyzed hydrolysis of olive oil in an AOT‐iso‐octane reversed micellar system was employed as a model. Three specific operational strategies have been considered, namely batch, fed‐batch, and fed‐batch‐bleed. Simulation shows the conversion of substrate to be strongly dependent on efficient use of the substrate, since the permeability coefficients of both substrate and product are quite similar. Sensitivity analyses were performed to assess the influences of various parameters (membrane area, substrate feed rate, solvent bleed rate and permeability) on the performance of the reactor in different modes of operation. The analyses presented are useful to assist the optimization of the operational strategy used for the RDMR system.
Reactor modelling for electrochemical processes
Authors: Scott K.
Published: July 2010

This paper presents a relatively straightforward approach to the modelling of electrochemical reactors operated in batch or continuous modes. The models are based on ideal flow assumptions of either well‐mixed or plug flow and incorporate reaction rate models based on electrochemical kinetics and mass transport at one electrode. General characteristics of the reactor models are described, particularly with regard to the need for good mass transport in metal recovery applications.

An example is given on the use of the model in the recovery of a heavy metal (Cd2+) from an acidified solution containing Cd(II) and Fe(III) ions. The reaction rate model is based on experimental data.
An evaluation of single resistance transfer models in the sorption of metal ions by peat
Authors: Allen Stephen , Brown Pauline , McKay Gordon , Flynn Orla
Published: July 2010

The adsorption of Pb2+, Cd2+, Cu2+, Zn2+ and Al3+ onto peat has been studied using a system of standardised batch adsorbers under equilibrium and transient rate conditions. Models based on the assumption of a single external mass transfer resistance to adsorption have been developed to attempt to predict the concentration decay curves obtained experimentally, for several variable system parameters, under transient batch conditions. In this instance the single resistance is taken as that of film diffusion of the sorbate through the liquid film surrounding the sorbent particle. Two methods of determining the external mass transfer coefficient have been used, one based on the Weber model and the other on the Furusawa‐Smith model.

Equilibrium data have been analysed and shown to conform to a linear Langmuir plot. The decay curves predicted by the models represented the experimental data very well, particularly at high sorbent masses. Under these conditions film diffusion appears to be the rate controlling step in the adsorption of metal ions by the peat. At low sorbent loadings, however, the influence of internal mass transfer is evident.
Effects of experimental variables on phosphate adsorption on bentonite
Authors: González‐Pradas E. , Villafranca‐Sánchez M. , Gallego‐Campo A.
Published: July 2010

The adsorption process of phosphate ions on a bentonite from Almería (East‐Andalucía, Spain) was studied at 30°C over a range of experimental conditions such as saline (0.1 M KCl) or non‐saline medium, natural or calcium homoionic bentonite and different pH values.

In order to calculate the adsorption capacities (Xm) of the samples, the experimental data points were fitted to the Langmuir equation. Xm values ranged from 0.42 μg P g−1 for the natural sample in non‐saline medium to 0.74 μg P g−1 for the same sample in saline medium, the Xm value corresponding to the calcium homoionic bentonite sample being intermediate. At different pH conditions, Xm increased from 0.28 μg P g−1 at a pH of 1.3 to 1.53 μg P g−1 at a pH of 4.4, and then decreased to 0.42 μg P g−1 at a pH of 8.7.
The thermal ignition of lignocellulosics in infinite slab and cubic geometries
Authors: Jones J. C. , Rahmati H. , Do T. D. H.
Published: July 2010

Wood shaving samples were heated in both cubic baskets and in a previously described system realising the conditions of the ‘infinite slab’ in thermal ignition. Results from the two sets of experiment were found to be totally consistent with each other.
Uptake of cerium, cobalt and cesium by Potamogeton crispus
Authors: Hafez Mohamed B. , Hafez Nabil , Ramadan Yasser S.
Published: July 2010

Cerium, cobalt and cesium and their isotopes were taken up inside Potamogeton crispus. The rate of uptake was subjected to environmental parameters such as pH, temperature, and interference by certain ions. Accumulation of cerium and cobalt inside 1 g of Potamogeton reached a quantity of 12 mg of Ce (III) and 3‐6 mg of Co (II). Also I g of Potamogeton can accumulate 12 KBq, 17 KBq and 20 KBq of Ce144, Co60 and Cs137 respectively. Rates of ion uptake by Potamogeton were increased by increasing pH and temperature and decreased in the presence of chemical additives. Potamogeton could be used to treat low level liquid radioactive waste.
Synthesis and application of some new heterocyclo‐5‐sulphonyl‐8‐hydroxyquinolines as antimicrobial agents
Authors: Hafez Ali A. Abdel , Awad Ibrahim M. A. , El‐Zohry Maher F.
Published: July 2010

A new series of 5‐sulphonyl‐(‐nicotinonitriles, pyridones and cyclohexenones)‐8‐hydroxyquinolines 2, 3 and 4 have been synthesised by Michael condensation of 5‐sulphonyl‐(4′‐arylidino‐3‐methyl‐2‐pyrazoline‐5‐one)‐8‐hydroxyquinoline 1 with malononitrile, ethylcyanoacetate and ethylacetoacetate respectively. The metal chelates for compounds 2 and 3 with Cu2+ Hg2+ and Fe3+ have been synthesised. All the prepared compounds were screened in vitro with some selected Gram‐positive and Gram‐negative bacteria.
Studies of L‐phenylalanine production by immobilised aminoacylase in stabilized calcium alginate beads
Authors: Lee Kong H. , Lee Pat M. , Siaw Yew S.
Published: July 2010

Aminoacylase I (EC 3.5. 1.14) was immobilised by entrapment in uncoated calcium alginate beads and calcium alginate beads coated with chitosan, polyethyleneimine and polyethyleneimine‐glutaraldehyde for the production of L‐phenylalanine by the hydrolysis of a racemic mixture of N‐acetyl‐DL‐phenylalanine. The operational stability, thermal stability, effects of pH and temperature and kinetic constants, Km and Vmax values of free and immobilised enzymes were studied. Scanning electron micrographs revealed differences in the structures of the surfaces of coated and uncoated beads. Chitosan‐coated calcium alginate beads was found to be the best among the immobilised systems studied. The activity and the optimum temperature of immobilised aminoacylase were higher than those of the free enzyme. In addition, the beads showed stable activity under operational conditions. The immobilised aminoacylase lost about 20% of its initial activity after ten cycles of reuse. Polyethyleneimine and polyethyleneimine‐glutaraldehyde treatments were also found to enhance the operational stability of the enzyme but its activity was greatly reduced.
Studies on the dechlorination and detoxification of organochlorine compounds (III). Polychlorinated dibenzo [1,4] dioxins and polychlorinated dibenzofurans
Authors: Stojkovski Stojan , James Bruce D. , Markovec Ladislav M. , Magee Robert J.
Published: July 2010

The Ni2B in‐situ catalytic dechlorination technique has been applied to the dechlorination and detoxification of polychlorinated dibenzo [1,4] dioxins and polychlorinated dibenzofurans. Dechlorination can be achieved in 3 h. Detection of the various chlorinated intermediates was obtained by GC/MS and these were identified by their characteristic mass fragments.
New dyestuffs for polyester fibres—synthesis and comparative tinctorial behaviour of 3‐alkyl‐4‐arylhydrazono‐N1‐picolinoyl‐2‐pyrazolin‐5‐ones and their isomeric pyrid‐3‐ and ‐4‐yl analogues
Authors: Hanna M. A. , Girges M. M. , Fadda A. A.
Published: July 2010

The condensation reaction of pyridine‐carboxylic acid hydrazides IIa‐d with ethyl butanoylacetate was selectively used to synthesize new azo‐disperse dyes embodying a pyrazolone moiety with a view to evaluating and comparing their dyeing performance on synthetic polymer fibres. Fastness properties of these dyes were of a generally good order, particularly for those of nicotinoyl derivatives VIIIa‐h. Comparison of the promising tinctorial properties (%R, K/S function and Tristimulus values) of the latter products with that of the corresponding oxygenated analogues Xa‐h revealed the advantages of using the former colourants as azo‐disperse dyes for the used polyester fibre.
A kinetic model for the decrease in lipase activity of rhizopus arrhizus and penicillium cyclopium mycelia in organic media
Authors: Tuccio Béatrice , Ferre Elisée , Comeau Louis , Lauricella Robert
Published: July 2010

The decrease in Lipase activity of Rhizopus arrhizus and Penicillium cyclopium mycelia (RAM and PCM) were studied in alkanes, ethers and chloroalkanes. The two biocatalysts showed similar behaviour in organic media, although RAM was slightly more stable. The kinetic model obtained indicated that the decrease in activity followed a succession of two first‐order reactions. Both RAM and PCM were more stable in hydrophobic solvents. These two mycelia were used to synthesize N‐octyl‐myristylamide; yield of the amide was linked in a linear relationship to the average activity of biocatalyst in the solvent employed.
Effect of pressure on the extractive biocatalysis of ethanol
Authors: Marques P. A. S. S. , Palavra A. M. F. , Cabral J. M. S.
Published: July 2010

The effect of pressure on the esterification reaction of ethanol with water‐immiscible organic acids, catalysed by a lipase from Mucor miehei (pH 4.5; 30°C), was studied through analysis of the kinetics and equilibrium parameters.

An increase of the ethanol distribution between the aqueous and organic phases was observed by the addition of lipase and the increase of the pressure in the system. Furthermore, the enzyme showed high specificity for the acid substrate, esterifying preferentially long chain fatty acids (C8‐C18). In the studies described oleic acid was used as substrate for the esterification reaction.

A kinetic study with the free enzyme, showed that pressure affected the extraction system, increasing the maximum reaction rate (> Vmax), the affinity (< Km) and the specificity (> Vmax/Km = ksp) of the enzyme to the substrate, probably due to the effect of pressure on the electrostatic interactions in biological systems.

The enzyme operational stability, at 30°C, improved significantly with the increase of pressure, having lower values for the deactivation constant (k) (8.3 × 10−3 h−1) and higher values for the half‐life times (t1/2) (77 h) in comparison with those obtained under atmospheric pressure conditions (k = 2.3 × 10−2h−1; t1/2 = 30 h).
Removal of thorium from simulated acid process streams by fungal biomass: Potential for thorium desorption and reuse of biomass and desorbent
Authors: Gadd G. M. , White C.
Published: July 2010

When thorium was biosorbed by biomass of Rhizopus arrhizus or Aspergillus niger it could be removed by treatment using carbonate solutions, but not by phosphates or distilled water. Desorption was rapid, reaching completion in 15 and 30 min respectively. Desorption efficiency was independent of the desorbent concentration above 0.05 mol dm−3 but was strongly dependent on the biomass concentration, decreasing as the biomass concentration increased for both species. Biomass from both species could be regenerated by desorption using sodium carbonate solutions and reused for biosorption. In both species, the efficiency of biosorption and desorption fell as the number of exposures increased although there was an initial rise in desorption efficiency for R. arrhizus. Biosorption and desorption efficiencies of A. niger biomass showed the steeper decline but both were severely reduced in R. arrhizus after five treatments. There was also a significant loss of biomass during repeated treatment but this was not apparently related to the loss of biosorption and desorption efficiencies. The same batch of sodium carbonate solution could be used to repeatedly desorb batches of biomass. The total amount of thorium removed was greater with increasing sodium carbonate concentration up to 0.1 mol dm−3. It was considered that reuse of both biomass and desorbent did not yield significant improvements in process economics.
Variations of ammonium ion concentration and solution pH during the hydrolysis of urea by urease
Authors: Huang Ting‐Chia , Chen Dong‐Hwang
Published: July 2010

Variations of product concentration and solution pH with reaction time during urea hydrolysis by urease, in both phosphate and citrate buffers, were studied. From the experimental results and the theoretical estimations based on the Michaelis‐Menten equation and the ionic equilibria of the species in solution, the inhibition behavior of urease by product and substrate was shown to be complex at high urea concentration. Furthermore, the ionic equilibria of the species in solution were significantly affected by the high concentrations of urea in the presence of buffer salts. Solution pH therefore changed to a lower value than that obtained with a lower concentration of ammonium ions. This phenomenon has not been reported and was contrary to the classic ionic equilibria. The observed results might be attributed to the character of urea and/or the more complex ionic equilibria of the species in solution.
A comparative study of the sonication of anaerobic and activated sludges
Authors: Morgan J. W. , Forster C. F.
Published: July 2010

Sonication was used to study the strength and structure of two activated sludges and a range of anaerobic sludge samples. Particle size analyses and turbidity measurements enabled the sludges to be ranked according to their aggregate strengths. This ranking was based on the floc strength constants of the samples and the critical energy values, above which no further disintegration occurred. Surface charge measurements confirmed previous structural models for activated and granular anaerobic sludges.
Thermal inactivation kinetics of penicillin g acylase obtained from a mutant derivative of escherichia coli atcc 11105
Authors: Erarslan Altan , Koçer Halil
Published: July 2010

Thermal inactivation kinetics of native and glutaraldehyde cross‐linked forms of penicillin G acylase obtained from a mutant derivative of Escherichia coli ATCC 11105 were studied. Apparent activation energies for thermal inactivation of both native and cross‐linked forms of enzyme were calculated to be [57‐71 ± 8.46] and [67.11 ± 13.83] kcal mol−1 respectively. This slight increase in activation energy‐suggested that glutaraldehyde cross‐linking did not markedly protect against thermal inactivation. Cross‐linked enzyme did, however, have a significantly improved half‐life at temperatures between 40°C and 50°C.
Phenol photodegradation over titanium dioxide
Authors: Trillas Maria , Pujol Montse , Domènech Xavier
Published: July 2010

The heterogeneous photocatalytic oxidation of phenol in aqueous diluted solutions over TiO2 particles under UV‐illumination has been investigated. It has been observed that the yield of the phenol photooxidation depends strongly on the pH of the solution. Maximum yields are obtained at pH 8 and also in very alkaline media. These results are explained considering the processes that take place at the surface of the semiconductor, in which OH radicals have an important role. With respect to the initial charge transfer steps a kinetic analysis has been performed. From this analysis it was deduced that the constant rate of formation of OH radicals is about 4.0 × 104 times greater than the constant rate of the direct reaction between phenol and photogenerated holes in the TiO2 particles. Finally, from HPLC analysis, hydroquinone, paraquinone and 1,2.4‐benzenetriol have been detected as intermediate products prior to the total phenol mineralization.
Nitriles in heterocyclic synthesis. Part II: Synthesis and application of pyrano[3,2‐h]quinoline sulphonamide derivatives
Authors: Hafez Ali A. Abdel
Published: July 2010

5‐Sulphonamido‐8‐quinolinol reacts with cinnamonitrile derivatives in the presence of a basic catalyst to give pyrano[3,2‐h]quinoline sulphonamide derivatives (8a‐d‐13a‐d). The reaction of 8b, 9b with some reagents such as acetic anhydride, acetic anhydride/pyridine mixture, formamide and formic acid/formamide mixture gave the fused heterotetracyclic systems pyrimido‐[4′, 5′: 6, 5]pyrano[3, 2‐h] quinoline sulphonamide derivatives. The structures of all newly synthesized compounds were confirmed by elemental analyses and spectral data. These compounds showed antimicrobial activity against some selected bacteria in vitro.
Kinetics of lactic acid fermentation on glucose and corn by Lactobacillus amylophilus
Authors: Mercier P. , Yerushalmi L. , Rouleau D. , Dochain D.
Published: July 2010

The biosynthesis of ammonium lactate, a product of lactic acid fermentation was studied from corn and glucose at five different pH values of 5.4 to 7.8. In the glucose fermentations, a 100% conversion of substrate was obtained resulting in a maximum lactic acid production yield of 93.2%. The optimum pH for the maximum volumetric rate of lactic acid biosynthesis (1.56 g dm−3 h−1) was between 6.0 and 6.5. The corn fermentations were slower than the glucose fermentations with a resulting lactic acid yield of 67.5%. Hydrolysis of corn by enzymatic or chemical methods as well as the use of ammonium hydroxide for pH control increased both the final concentration and the rates of lactic acid production. An enhanced yield of more than 90% was finally obtained in the corn fermentations. A logistic model adequately described the kinetics of biomass growth, lactic acid production and sugar utilization in the glucose fermentations at different pH values. The dynamics of lactic acid formation in the corn fermentations were also successfully described by the developed model. The dependence of the model parameters on pH was investigated.
Intrinsic kinetics of nickel/calcium aluminate catalyst for methane steam reforming
Authors: Soliman M. A. , Adris A. M. , Al‐Ubaid A. S. , El‐Nashaie S. S. E. H.
Published: July 2010

A new catalyst for steam reforming of methane based on nickel/calcium aluminate is prepared. The new catalyst has shown stability and high activity at low steam to methane ratios. In this paper the intrinsic rate equations are derived and parameters estimation made. The rate equations show non‐monotonic dependence on steam partial pressure. The rate equations also show that the primary product is CO2 while CO is formed via the reverse water‐gas shift reaction. The mechanism proposed and the rate equations obtained indicate that it may be essential to propose specific rate models for any given catalyst rather than generalized mechanism and rate models.
Optimisation of the synthesis of 5‐chloromethyl‐2‐furancarboxaldehyde from D‐fructose dehydration and in‐situ chlorination of 5‐hydroxymethyl‐2‐furancarboxaldehyde
Authors: Sanda Komla , Rigal Luc , Gaset Antoine
Published: July 2010

A stepwise method for the conversion of D‐fructose into 5‐chloromethyl‐2‐furancarboxaldehyde is described. The sugar was first subjected to acid‐catalysed dehydration in N,N‐dimethylformamide to give 5‐hydroxymethyl‐2‐furancarboxaldehyde as an intermediate. The latter was then chlorinated in situ with phosphorylchloride, to give the named chloro‐compound in an 85% overall yield, in the absence of any humic matter or tarry product.
Synthesis and application of some new oxazole derivatives as antimicrobial agents
Authors: Bakhite Etify A. , Mohamed Thana A. , Abdel‐Rahman Abdu E.
Published: July 2010

5‐(p‐Acetylphenyl)‐2‐phenyloxazole (I) was condensed with aromatic aldehydes to furnish chalcones 2a‐e. Cyclocondensation of 2a‐e with hydrazine hydrate and with phenyl hydrazine led to the formation of pyrazoline derivatives 3a‐e and 4a‐e respectively. Similarly, 2a was interacted with hydroxylamine to give isoxazoline (5). On the other hand, condensation of 1 with phenyl hydrazine yielded hydrazone 6 which on treatment with Vilsmeier reagent (DMF/POCl3) gives 5‐[p‐(4‐formyl‐1‐phenylpyrazol‐3‐yl)phenyl]‐2‐phenyloxazole (7). Also, a few derivatives of 7 have been prepared. Moreover, all compounds were screened for their antimicrobial activity against some strains of bacteria and fungi.
The use of modified divinylbenzene‐polystyrene resins in the separation of fermentation products. A case study utilizing amino acids and a dipeptide
Authors: Casillas J. L. , Addo‐Yobo F. , Kenney C. N. , Aracilxs J. , Martínez M.
Published: July 2010

The adsorption of phenylalanine, aspartic acid, asparagine and aspartame from phosphate‐buffered aqueous solutions with modified divinyl‐benzene‐polystyrene resins has been investigated using high pressure liquid chromatography (HPLC). The pH studied was 2.8, the temperature range was 293‐313 K and the ionic strength was maintained at 1.0 mol dm−3. Over the range of variables investigated, the adsorption isotherms are linear and may be characterized by temperature and pH‐dependent apparent adsorption equilibrium constants, characteristic of the resin‐adsorbate system. By studying the dependence on temperature of this adsorption constant, heats of adsorption and entropy of adsorption have been estimated. In terms of the heat liberated on adsorption, the amino acids and a dipeptide can be ranked thus: aspartame > phenylalanine > aspartic acid > asparagine.
Artificial lighting system design for photosynthetic studies
Authors: Mouget Jean‐Luc , De La Noüe Joël , Legendre Louis , Jean Yves , Viarouge Philippe
Published: July 2010

Most artificial lighting systems operate with a 100‐120 Hz flickering, an undesirable condition for studies on photosynthesis, requiring a fluctuating (flashing light effect) as well as a constant light flux. The amplitude of this flickering depends on the type of lamps and on the power supply. Selected lamps and related power supplies providing a flickering‐free light source are critically reviewed. A new system is proposed, that combines a high intensity discharge lamp (simulating natural sunlight) with a high‐frequency (>40kHz) ballast. This power supply provides a flickering‐free light flux, and offers such advantages as the use of lamps with high energy output and long life expectancy.
Spiroheterocyclic system. Part IV: Novel azo dye sulpha drugs of spiroheterocyclic naphthenes
Authors: Awad Ibrahim M. A. , Hafez Ali A. Abdel , El‐Zohry Mahr F.
Published: July 2010

Novel azo‐dyes have been synthesized by diazotization of 4‐amino benzene‐4′‐(substituted heterocyclo) sulphonamide derivatives and coupling with 1‐oxa‐4‐thia‐spiro[4,4]nonan‐2‐one (I) and/or with l‐oxa‐4‐thia‐spiro[4,5]decan‐2‐one (I′) in acid medium to give the corresponding 3‐azo‐(4′‐substituted benzenesulphonamido)‐l‐oxa‐4‐thia‐spiro[4,4]nonan‐2‐one (II‐IX) and/or l‐oxa‐4‐thia‐spiro[4,5]decan‐2‐one (II′‐IX′] as spiro‐ligands. Treatment of these ligands with metal salts of iron (Fe3+), copper (Cu2+) and mercury (Hg2+) as chlorides in ethanolic solution furnished the corresponding metal chelates (IIa‐c‐IXa‐c) and/or (II′a‐c‐IX′a‐c). The compounds were tested in vitro for antimicrobial activity to study the structure‐activity relationship.
Synthesis and biological study of some pyrrolopyridine derivatives
Authors: Mohamed Thana A.
Published: July 2010

Quinoline dicarboxylic anhydride (1) reacted with p‐aminoacetophenone to give a pyrrolopyridine derivative (2). The compound produced (2) reacted with hydrazine hydrate, hydroxyl amine hydrochloride, semicarbazide and thiosemicarbazide to produce pyrrolopyridine derivatives (3‐6). Compound 3 reacted with aromatic aldehyde, PhNCS or PhNCO to produce compounds 7‐9. Compound 4 reacted with PhNCO to give the carbamate ester 10. When compound 5 was boiled with SOC12, the thiadiazolo compound (11) was obtained. When compound 6 was allowed to react with α‐haloesters and α‐haloketones, the thiazolo compounds (12‐14) were produced. All the synthesized compounds were tested against some Gram‐positive and some Gram‐negative bacteria and they gave satisfactory results.
Synthesis and surface activity of sodium salts of branched perfluorocarboxylic acids and their analogs containing one chlorine atom
Authors: Meissner Egbert , Myszkowski Jerzy , Szymanowski Jan , Sobczyńska Anna
Published: July 2010

Individual sodium salts of branched perfluorocarboxylic acids, (CF3)2CF(CF2CF2)nCOONa, and their analogs containing one chlorine atom, CF3CF(CF2CI)(CF2CF2)nCOONa, were synthesized by telomerization of 2‐iodoheptafluoropropane and l‐chloro‐2‐iodohexafluoropropane with tetrafluoroethene, the addition of ethylene to both types of iodides considered, HI elimination and the oxidation of perfluoroalkylethylenes with potassium bichromate. The surface tension measurements demonstrated the high surface activity of sodium salts containing 9 and 11 carbon atoms in the hydrophobe. Perfluorocompounds were more surface active than their analogs having one chlorine atom but the differences were not great.
Ultrafiltration membranes for the separation of catalyst and products in homogeneous catalysis systems
Authors: Halligudi S. B. , Khan M. M. Taqui , Desai N. V. , Rangarajan R. , Rao A. V.
Published: July 2010

Results of preliminary studies on concentration by ultrafiltration and reuse of a Ru(III)EDTA complex in homogeneous catalysis are reported. A method of preparation and selection of conditions of making cellulose acetate membranes for concentrating Ru(III)EDTA is described. At an operating pressure of 75 psig (517 kPa), the above catalyst can be concentrated to seven to eight times its initial concentration. The membrane used exhibits a separation of about 97.5 % for the complex with a permeate flow rate of about 3–6 gallons per sq. ft per day. The catalyst activities were determined for two reactions, viz. hydroformylation of 1‐hexene and carbonylation of ammonia for five cycles of concentration followed by reuse. The experimental data indicated that the catalyst concentration by ultrafiltration for subsequent reuse is simple and attractive and can provide potentially energy saving alternative to the cumbersome conventional separation processes associated with the recovery of catalysts in homogeneous catalysis.
A comparative study of the performance of solid supported and soluble urease for the enzymatic hydrolysis of urea
Authors: Demirel Günay , Akovali GÜNeri , Tanyolac Abdurrahman , Hasirci Nesrin
Published: July 2010

The performance of both free and solid supported urease for the enzymatic hydrolysis of urea was studied. Kinetic analysis of reaction rate data shows that the kinetic data were consistent with the proposed model. Statistical tests validated the model. Despite the deactivation of ureases, the immobilized enzyme could be the choice for a technological process aiming at the detoxification of blood in haemoperfusion columns.
Nitriles in heterocyclic synthesis. Part III: New sulpha drugs related to cyanopyridine derivatives
Authors: Hafez Ali A. Abdel , Awad Ibrahim M. A. , Monem Maisa I. Abdel
Published: July 2010

4‐Hydroxyacetophenone (1) was reacted with cinnamonitrile derivatives (2–6) to give 3‐cyano‐4‐(substituted phenyl)‐6‐(p‐hydroxyphenyl)‐pyridines (7–11). Interaction of compounds 7–9 with 4‐substituted heterocyclo‐benzenesulphonyl diazoniura chloride gave the corresponding 3‐cyano‐4‐(sub‐stituted phenyl)‐6‐(3′‐azobenzene sulphonamido‐4′‐hydroxyphenyl) pyridines (12–29). The corresponding iron (III) copper (II) and mercury (II) chelates were also prepared in a 1:2 metal‐to‐ligand ratio. All the synthesized compounds were characterized on the basis of microanalysis, IR and 1H‐NMR spectrometry.
Contributions of the crosslinked and noncrosslinked moieties to the solvent‐induced swelling of brown coals
Authors: Jones J. C. , Lim G. S. H. , Sananikone D. S.
Published: July 2010

A suite of brown coals from different sources was examined for solvent‐induced swelling in two forms: oven‐dried whole coal and pyridine‐extraced coal. This enabled the swelling to be resolved into the component due to imbibition of solvent by the crosslinked part and the component due to the non‐crosslinked part.
Experiments to promote colour changes in wool
Authors: Cottle D. J. , Zhao W. , Jones J. C.
Published: July 2010

Wool colour is not stable and it changes during storage. This study developed wool challenge methods by using a one‐week water bath incubation at 40°C or incubation overnight at a higher temperature to promote colour changes in wool. The study showed that the bacteria present in raw wool play a significant role in colour biodegradation during challenge (storage). A stable wool colour could be obtained for wool specification after a challenge treatment before colour measurement.
Zirconium‐based intermetallics as heterogeneous catalysts for the fischer‐tropsch reaction: I. Zr‐Ni‐Co catalysts
Authors: Al‐Shammary A. F. Y. , Caga I. T. , Tata A. Y. , Winterbottom J. M. , Harris I. R.
Published: July 2010

Alloys of the general formula Zr50NixCO50‐x, where 0 ≦x≧ 50, have been prepared and used in the temperature range 300–400°C, in the pressure range 1–9 barg in a microtubular reactor for the reaction of hydrogen with carbon monoxide to give hydrocarbons.

The alloys or intermetallic materials were prepared by argon arc melting, powdered by hydrogen decrepitation and characterised by means of optical microscopy (metallography), scanning electron microscopy with surface analysis and magnetic susceptibility measurements.

The selectivity towards higher hydrocarbons increased with (i) increase in the total pressure and (ii) decrease in hydrogen content of the feed gases. The kinetics were found to be of the form:

where m = 1.0 ± 0.2 and n = 0. The apparent energy of activation (Ea) lay in the range of 80–130 kJ mole−1 and there appeared to be a compensation effect between Ea and the pre‐exponential factor A.

The turnover numbers for the reaction exhibited an activity maximum for alloys of composition around Zr50Ni40Co20 and Zr50Ni30Co20. Magnetic susceptibility measurements indicated that alloys changed their nature from moderately paramagnetic to strongly paramagnetic or even ferromagnetic after use and this is attributed to the conversion of zirconium to zirconium oxide during reaction with the attendant production of free 3d‐transition metals. Derived catalysts prepared by air treatment of the hydrogen‐decrepitated intermetallics behaved almost identically to the latter materials and gave similar magnetic susceptibility values to used hydrided materials.
Zirconium‐based intermetallics as heterogeneous catalysts for the fischer‐tropsch reaction: II. Zr‐Ni‐Cu catalysts
Authors: Al‐Shammary A. F. Y. , Caga I. T. , Tata A. Y. , Winterbottom J. M. , Harris I. R.
Published: July 2010

Intermetallic alloys of the general formula Zr50NixCu50‐x (where 0 ⩽ × ⩽ 50) were prepared by argon arc melting and powdered by hydrogen decrepitation. These materials were used as catalysts for the H2/CO reaction in the temperature range 300–400°C, in the pressure range 1–9 barg and for H2/CO ratios in the range 1 to 5. Derived catalysts were prepared by air treatment of the hydrided alloys and were subjected to identical investigations to the latter.

The hydrided and derived catalysts behaved in a very similar manner in terms of selectivity, which increased with respect to higher hydrocarbon production with (i) increasing total pressure, (ii) decreasing values of H2/CO and (iii) increasing copper to the extent where CH4 contents was < 50% of the products. Increased temperature gave rise to increasing methane production. The activity of the alloy system exhibited a sharp activity maximum at the nickel‐rich end of the series and the copper‐rich alloys were almost ten times less active. The initial rate equation was observed to be of the form:

However, whereas n = 0, m varied between 0.5 and 1.2 for both series of catalysts.

The presence of copper promotes the formation of higher hydrocarbons, especially the formation of ethene. It is presumed that the presence of copper at the surface inhibits the polyerization of CHX species and favours the CO insertion.