bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modelling of the extraction equilibrium of zinc from chloride solutions with tri‐n‐octylphosphine oxide
Authors: Juang Ruey‐Shin 
Published: July 2010

AbstractThe 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

AbstractEight 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

AbstractA 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

AbstractNonionic 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

AbstractA 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

AbstractThis 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

AbstractThe 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

AbstractThe 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

AbstractWood 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

AbstractCerium, 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

AbstractA 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

AbstractAminoacylase 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractWhen 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

AbstractVariations 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

AbstractSonication 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

AbstractThermal 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

AbstractThe 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

Abstract5‐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

AbstractThe 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.