bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of crystallinity ratio and some physicochemical properties of poly(4‐methyl‐1‐pentene)
Authors: Yazici O. , Cakar F. , Cankurtaran O. , Karaman F. 
Published: March 2009

AbstractIt was determined that the thermal stability of poly(4‐methyl‐1‐pentene) (P4MP) was maintained up to 424°C in an inert atmosphere by thermogravimetric analysis. The retention diagrams of ethyl acetate, tert‐butyl acetate, and benzene on P4MP were plotted at temperatures between 30 and 280°C by inverse gas chromatography (IGC) technique. Melting temperature of the polymer was determined as 230 and 239.5°C by IGC and differential scanning calorimetry (DSC), respectively. The percent crystallinity of P4MP was obtained from the retention diagrams at temperatures below melting point. The percent crystallinity obtained by IGC is in good agreement with the ones obtained by DSC. Then, specific retention volume, V, weight fraction activity coefficient, Ω, Flory‐Huggins polymer‐solvent interaction parameter, χ, equation‐of‐state polymer‐solvent interaction parameter, χ, and effective exchange energy parameter, Xeff of octane, nonane, decane, undecane, dodecane, tridecane, n‐butyl acetate, isobutyl acetate, isoamyl acetate with P4MP, were determined between 240 and 280°C by IGC. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Rethinking Arsenate Coordination at the Surface of Goethite
Authors: Loring John S. , Sandström Malin H. , Norén Katarina , Persson Per 
Published: March 2009

AbstractWhen the truth stands on one leg: Arsenate coordinates at the water–goethite interface in a predominately monodentate fashion (see picture), a finding that impacts oxoanion bioavailability and challenges theories of mineral dissolution and surface complexation.magnified imageA fundamental precept of geochemistry is that arsenate coordinates at mineral surfaces in a predominately bridging‐bidentate fashion. We show that this is incorrect for the model system, arsenate adsorbed at the surface of goethite (α‐FeOOH), using a combination of XRD, EXAFS, and IR spectroscopic results. We report the crystal structure of pentaamminecobalt(III) arsenate, which consists of monodentate‐coordinated metal–arsenato complexes that have CoAs distances of only 3.25 Å. This result implies that metal–arsenic distances are not diagnostic for the coordination mode of arsenate. We show that the K‐edge EXAFS spectra of pentaamminecobalt(III) arsenate and arsenate–goethite surface complexes are strikingly similar, which suggests that arsenate could be coordinated at the goethite surface in a monodentate fashion. Refinements of thek3‐weighted EXAFS spectra of arsenate adsorbed on goethite results in values of CNAsFebetween 0.8–1.1 (±0.7), and there is no evidence that the coordination mode of arsenate changes as a function of pH or arsenate surface coverage. We report IR spectra from the first simultaneous IR and potentiometric titration of arsenate adsorbed on deuterated goethite (α‐FeOOD) in D2O, and we show for the first time the AsO stretching bands of arsenate–goethite surface complexes. We deduce that arsenate–goethite surface complexes are un‐, singly , or doubly protonated, depending on pH, from a principal component analysis of the AsO stretching region and an interpretation of the Type‐B OH stretching region. In summary, our cumulative results show that arsenate coordinates at the water–goethite interface in a predominately monodentate fashion. Furthermore, we find no evidence for bridging‐bidentate coordination, which is a finding that impacts oxoanion bioavailability and challenges theories of mineral dissolution and surface complexation.
A study of interactions between soil fractions and PAH compounds in thermal desorption of contaminated soils
Authors: Maguire Vineeta , Svrcek William Y. , Mehrotra Anil K. , Razzaghi Minoo 
Published: March 2009

AbstractThe interactions between three polynuclear aromatic hydrocarbons (PAHs), namely fluorene, naphthalene and anthracene, and three fractions of a soil, namely fulvic acid (FA), humic acid (HA) and humin/inorganic fractions, were studied experimentally. Prepared PAH + soil fraction binary mixtures, with PAH concentrations ranging over 0.8–7 mass%, were tested using a differential scanning calorimeter (DSC) over a temperature range of 20−390°C. The DSC thermograms for the PAH + HA mixtures showed distinctly different characteristics compared to mixtures with the other two soil fractions, where the endothermic peak for the vaporization of the PAH was absent. With the aid of vapour‐liquid flash calculations, the lack of the boiling point peak is interpreted to be due to the liquid‐phase miscibility of the PAHs and the HA fraction. Implications of the DSC results on the design and performance of the thermal desorption process are discussed.
Carbon dioxide absorption into a stable liquid rivulet
Authors: Nawrocki P. A. , Chuang K. T. 
Published: March 2009

AbstractThe wetting of the flow surfaces in heat exchangers, trickle‐bed reactors and columns containing structured packing has been shown to be discrete in nature involving rivulets. Detailed, fundamental modelling of the flow structure and transport processes occurring in rivulet flow is required in order to provide a basis from which more complex models can be built describing the overall processes occurring in the particular application of interest. To demonstrate the applicability of detailed rivulet modelling, theoretical analysis of the velocity and mass transfer characteristics in rivulet flows in an inclined, flat plate absorber has been performed. These theoretical results are compared with experimental data.
The solubility of ethane in n‐methylpyrrolidinone
Authors: Henni Amr , Lal Dhiraj , Mather Alan E. 
Published: March 2009

AbstractThe solubility of ethane in N‐methylpyrrolidinone (NMP) has been measured at −10, 25, 40, 50, 70, 75, 100, and 120°C at pressures up to 7.1 MPa. The solubility data obtained are compared with those of ethane in other physical solvents. The results were correlated with the Peng‐Robinson (1976) equation of state and the interaction parameters were obtained. Henry's constants were also determined.
Horizontal cross flow filtration and rinsing of ice from saline slurries
Authors: Dickey Leland C. , Dallmer Michael F. , Radewonuk E. Richard , Mcaloon Andrew 
Published: March 2009

AbstractContinuous filtration of ice slurries (with particles of about 80 μm diameter) to generate potable water was investigated. In the filtration process the ice is driven through a stationary channel with liquid draining through narrow slots in the base. Most of the liquid drained from the slurry at ambient pressure and the residual liquid trapped in the pores of the consolidated ice bed was displaced to a vacuum after downstream rinsing with sprayed or melt water. The cost of this approach may be competitive with reverse osmosis if an automated unit is developed.
Hardwood fibre fractionation using rotating cone
Authors: Rewatkar V. B. , Masliyah J. H. 
Published: March 2009

AbstractRotating cones were used to carry out fibre fractionation of a 100% hardwood pulp having a consistency of 0.93± 0.02%. The unique features of the rotating cone fractionator adopted in this study were that its surface was constructed from a sieve mesh, thereby introducing a “rough” surface, and the feed pipe was located at an off‐centre position to the axis of rotation. In all earlier studies reported in the literature, the fibre fractions were collected at different radial locations. However, in the present study, collection of the various fractions was made either at different radial or at angular positions. Tests were conducted for 120 mm diameter cones having a cone angle of 30°.Visual observations, photographs and fibre length measurements suggested that fibre fractionation performance strongly depended on the flow characteristics formed on and surrounding the rotating cone. In turn, they were found to be strongly dependent on the surface roughness, rotational speed and feed flow rate. Results for fibre fractionation showed quite conclusively that rotating cones made from 20‐mesh and 32‐mesh screens were more effective for fibre fractionation than “smooth” surface rotating cones.
Optimized design of wastewater treatment systems: Application to the mechanical pulp and paper industry: I. Design and cost relationships
Authors: Fels Mort , Pintér János , Lycon David S. 
Published: March 2009

AbstractFour different end‐of‐pipe waste‐treatment processes applicable to mechanical pulp and paper manufacture were modelled. Calculated costs for an average mill were capital $34–$44 million, operating cost $3.5–$6 million/year and discounted (10 years) $60–$85 million. Compared with mill reported values, capital and operating costs of activated sludge treatment (AST) were higher by 17 and 29%, respectively; those for aerated stabilization basin (ASB) were higher by 27 and 180%. Major variables affecting the costs were BOD and TSS levels and the wastewater‐to‐pulp ratio. It was concluded that ASB is more economical than AST and that anaerobic treatment plus AST could be advantageous at high BOD levels.
Through a glass, darkly: Kinetics and reactors for complex mixtures syncrude innovation award lecture
Authors: Gray Murray R. 
Published: March 2009

AbstractThe concepts of chemical reaction engineering are powerful, because the most basic design equations are applicable to a wide range of physical phenomena. For example, the applicability of the ideal continuous‐flow stirred tank reactor goes far beyond chemical reactors to include biological, medical and environmental processes. The difficulty in analyzing these processes is not in formulating an appropriate reactor equation, but in modeling the chemical kinetics. The challenge is to define kinetic rate equations that allow for the mixtures of reactants and mixtures of catalysts, especially given incomplete information. Examples drawn from biology and medicine illustrate reaction kinetics that are complex due to the nature of the catalyst.In contrast, processes for upgrading of bitumen to more valuable products exhibit ill‐defined reaction chemistry and mixtures of thousands of reactants and products. The need to define kinetics for such mixtures has given rise to several distinct approaches, including empirical rate equations, simplification to model reactions, lumped kinetics and Monte Carlo simulation. A summary of these methods shows that the key element for successful kinetic modeling is creative definition of a model, followed by vigorous testing of the model to determine its ability to predict performance.
Scalar mixing measurements in batch operated stirred tanks
Authors: Distelhoff M. F. W. , Marquis A. J. , Nouri J. M. , Whitelaw J. H. 
Published: March 2009

AbstractAn LIF technique was used to obtain unobtrusive measurements of scalar concentration as a function of time and mixing times in a fully baffled batch operated mixing vessel agitated by five forms of impeller (Rushton, ‘bucket’, six bladed 45°‐and 60°‐pitched blade, hyperboloid).The mixing time was comparable to the time required for the dye/scalar to be transported from the top of the vessel to the bottom part plus the time required for a further two rotations of the bulk flow in the circumferential direction. At constant power input the mixing times for similar impellers were similar, although different for different types.
Exploration of mesoporous structure of tunisian raw and acid‐leached phosphate ore particles
Authors: Brahim F. Ben , Mgaidi A. , El Maaoui M. 
Published: March 2009

AbstractRock phosphate fractions were examined for their porous structure by nitrogen adsorption. The pore size distribution and the shape of pores does not seem to depend on the particle size. The specific surface area values present two regions, one above and one below that of the particles with 125 μrn diameter. Particles of a given size were leached with dilute phosphoric acid (1.5 mass% P2O5) at 25°C. It was observed that there is a widening of the initial pores during leaching. The particles collected at the initial period of the reaction are pitted and those collected at the final period are disintegrated.
Vortex shedding and turbulence scales in staggered tube bundle flows
Authors: Balabani S. , Ylannekis M. 
Published: March 2009

AbstractTime‐resolved LDA measurements of the axial and transverse velocity components were performed in the first 6 rows of a staggered tube bundle with relative transverse and longitudinal pitch ratios of 3.6 and 1.6, respectively. Measurements were carried out in a flow of water at a Red of 12,858. A flow periodicity with a Strouhal number equal to 0.26 was detected, which is in agreement with published data. This periodicity was found to broaden the turbulence levels by up to 50% in some locations. Agreement between the experimental results and previously reported CFD predictions using the k‐ϵ model improved when this periodic component was removed from the spectra using appropriate filtering techniques. In an attempt to describe the turbulence structure more extensively, time‐ and length‐scales and dissipation rates were estimated from the filtered time‐resolved data. Integral time scales were on average equal to 4 ms and Taylor microscales 0.7 ms. Comparisons of the data with numerical predictions show promise for more extensive evaluation of CFD predictions in hture than has been possible hereto.
Ecoulement de fluides newtoniens et non newtoniens à travers des lits fixes stratifiés
Authors: Sabiri Nour‐Eddine , Comiti Jacques 
Published: March 2009

AbstractDes lits stratifiés de plaquettes sont étudiés selon deux configurations opposées “écoulement‐particule”. Dans les deux configurations, à partir de mesures de chutes de pression effectuées avec un fluide newtonien, deux paramètres struc‐turaux caractéristiques du milieu sont déterminés à l'aide d'un modèle de type capillaire. Les différences concernant leur comportement hydrodynamique sont analysées et un facteur d'anisotropie est défini. Une équation adimensionnelle per‐mettant la détermination des chutes de pression lors de l'écoulement de fluides newtoniens et non newtoniens purement visqueux dans les deux configurations, sur un large intervalle de nombres de Reynolds, est proposée et validee expéri‐mentalement.
Pipeline scale‐up in drag reducing turbulent flow
Authors: Sood Arun , Rhodes Edward 
Published: March 2009

AbstractModels available in literature for predicting drag reduction scale‐up are inadequate as they have been successful only over a narrow range of diameters. A new scale‐up model is presented which equates dampening of turbulent velocity fluctuations by drag reducing additives to a reduction in the Prandtl mixing length. Flow and pressure drop data from a laboratory scale pipe along with shear viscosity measurements are sufficient to predict drag reduction scale‐up in bigger diameter pipes. Using this approach, scale‐up was successfully predicted over a diameter range of 7 to 154 mm for a surfactant‐water system and 26.6 to 1194 mm for a polymer‐oil system.
Ordonnancement à court‐terme d'un atelier discontinu de chimie fine
Authors: Baudet Philippe , Azzaro‐Pantel Catherine , Domenech Serge , Pibouleau Etluc 
Published: March 2009

AbstractCette étude utilise certains concepts de productique pour résoudre des problèmes d'ordonnancement en génie des procédés. Nous étudions le cas de l'atelier discontinu multi‐objectifs de chimie fine, qui présente des contraintes très complexes: diversité des produits et de leurs procédés d'élaboration, intermédiaires réactionnels, politiques de stockage particulières, vérification de bilans matières, consommations d'utilités, limitation du taux de rejet de produits polluants. Un modèle de simulation détaillé du fonctionnement d'un atelier discontinu de chimie fine est proposé dans cet article. Sa mise en oeuvre et l'exploitation des résultats sont ensuite présentées. Les applications proposées ici nous paraissent intéressantes pour une gestion de production plus efficace mais également pour répondre à des préoccupations classiques en génie des procédés (conception d'ateliers, traitement des effluents, stockage et stabilité d'intermédiaires réactionnels).
A study of mass transfer behaviour in a catalytic distillation column
Authors: Huang Chuncheng , Podrebarac Gary G. , Ng Flora T. T. , Rempel Garry L. 
Published: March 2009

AbstractCatalytic distillation (CD) is a process where reaction and separation take place simultaneously in a distillation column. Recently, a new CD process for the aldol condensation of acetone to diacetone alcohol and mesityl oxide was developed in our laboratory. Owing to the unique structure used to support catalysts in the CD column, mass transfer data are needed to model the CD process. The mass transfer behaviour in the CD column has been studied both for the reactive and non‐reactive sections of the column in our laboratory. Based on the experimental results, general correlations for the mass transfer coefficients have been established and the 95% confidence intervals for the associated parameters were obtained. The experimental results indicated that the catalyst bags did not play a significant role for the separation between the vapour and liquid phases. The mass transfer correlations developed in this study have been used successfully to model the CD process for the aldol condensation of acetone carried out in our laboratory.
Axial mixing in a 15 cm diameter reciprocating plate bubble column
Authors: Baird Malcolm H. I. , Rao Nadella V. Rama 
Published: March 2009

AbstractAxial dispersion coefficients (E) in the liquid phase have been measured by unsteady tracer response methods in a 15 cm internal diameter reciprocating plate bubble column, using air and water in countercurrent and cocurrent flow. The operating variables studied were amplitude (0.6–1.27 cm) and frequency (0–5 Hz) of reciprocation, and the superficial velocities of the liquid and gas phases and the spacing between plates. Three types of plate were studied; conventional Karr‐type plates with perforation diameters 1.43 cm, plates with smaller (0.635 cm) perforations, and single‐perforation (doughnut) plates with internal diameter 7 cm. Measured values of E ranged from about 1 cm2/s to a maximum of 116 cm2/s. In general, the plates with 0.635 cm perforations gave the smallest values of E while the largest values of E were obtained with the doughnut plates, due to vortex ring shedding. The single liquid phase data for the three types of plate were approximately consistent with the correlation of Stevens and Baird (1990). The gas‐liquid flow results were interpreted in terms of several different hydrodynamic effects.
Characterization of stirred vessel hydrodynamics by three dimensional trajectography
Authors: Wittmer Stephan , Falk Laurent , Pitiot Pascal , Vivier Hervé 
Published: March 2009

AbstractA simple method has been developed to track the three‐dimensional motion of a small particle convected in a stirred tank for about 1 h. Different flow patterns induced by a Rushton or a pitched blade turbine have been studied. The results have been compared with known results obtained by conventional techniques. Several tools which have been proposed for this purpose give rise to new insights and interpretation of transport and mixing processes in stirred tanks for engineering applications.
Effect of micro‐mixing on the yield of intermediates in triplet consecutive/competitive reactions
Authors: El‐Hamouz Amer M. , Mann Reginald 
Published: March 2009

AbstractMicro‐mixing calculations based upon a simplified non‐deforming one‐dimensional diffusion‐reaction formulation are presented for the sequence of three reactions denoted by A + B → R + B → S + B → T. This triplet reaction under micro‐mixing is posed as five simultaneous parabolic partial differential equations which have been solved using a general purpose NAG library algorithm. The primary product R has an improved yield under perfect mixing conditions. The ultimate product T is shown to be always favoured by the perfect segregation of micro‐mixing. By contrast, the central intermediate S gives high yields under micro‐mixing at low conversions, but perfect mixing is preferable at higher conversions. In addition, predictions show that yield improvements for S might be possible by an engineered stretching of fluid lamellae and by the combination of micro‐mixing followed by perfect mixing, especially at intermediate levels of conversion. The calculations are relevant to multi‐step halogenations and they help to explain how the anomolous appearance of a tri‐halogenated species ahead of mono‐ and di‐halogenated ones in a stirred vessel can be attributed to micro‐mixing.
Quantitative description of the chloride effect on chlorine dioxide generation from the ClO2‐HOCl reaction
Authors: Yin Guohong , Ni Yonghao 
Published: March 2009

AbstractThe generation of chlorine dioxide from the reaction between hypochlorous acid and chlorite with or without an initial chloride addition has been studied under slightly acidic conditions. Chloride (Cl‐), one of the products from the reaction, not only changes the reaction stoichiometry, but also alters the rate law. It was found that the formation of chlorine dioxide from the HOCI‐ClO2‐ system consists of two distinct parts, one is promoted by chloride, the other is independent of chloride. The overall kinetics of the chlorine dioxide generation from the reaction is:

This model can very well predict the reaction under the following conditions: \documentclass{article}\pagestyle{empty}\begin{document}$ 273 - 303{\rm K},\left[ {ClO_2^ - } \right] = 0.001 - 0.00267\;{\rm mol}/{\rm L},\left[ {ClO_2^ - } \right]/\left[ {HOCl} \right] = 2,\;{\rm and}\;{\rm pH}\;3.86 - 4.91 $\end{document}
Ozonation and photodegradation kinetics of pollutant acids in wastewaters
Authors: Benitez F. Javier , Beltran‐Heredia Jesus , Gonzalez Teresa , Real Francisco 
Published: March 2009

AbstractThe kinetics of the degradation of four phenolic acids by ozonation and polychromatic UV radiation were investigated. The acids: p‐hydroxyphenylacetic, homoprotocatechuic (3,4‐dihydroxyphenylacetic acid), gentisic (2,5‐dihydroxybenzoic acid) and 2,3‐dihydroxybenzoic, have been selected because of they constitute major pollutants present in some agro‐industrial wastewaters. The p‐hydroxyphenylacetic acid was initially ozonated and UV irradiated alone. Its kinetic constants and reaction orders in the ozonation process were deduced by using a model based in the film theory which takes into account the mass transfer with the chemical reaction. The quantum yields in the photodegradation process were evaluated from a simple reaction mechanism with the help of an emission model to determine the radiation flow rate absorbed. Later, in the simultaneous ozonation and UV photodegradation of the mixtures of the four acids, competitive kinetic methods were developed to determine the individual rate constants between ozone and each acid in the ozonation process, and the individual quantum yields for every acid in the photodegradation process.
Solubility of acid gases in a mixed solvent
Authors: Lal Dhiraj , Otto Frederick D. , Mather Alan E. 
Published: March 2009

AbstractThe solubility of the acid gases, H2S and CO2, and their mixtures in a mixed solvent consisting of 55 mass% 2‐piperidineethanol, 10 mass% sulfolane and 35 mass% water has been determined at 40° and 100°C. Partial pressures of the acid gases ranged from 0.05 to 5550 kPa.