bluuebunny/crossref_metadata_2025_split huggingface dataset:
On Criteria for Occurrence of Azeotropes in Isothermal and Isobaric Binary Systems
Authors: Missen Ronald W. 
Published: July 2010

AbstractCriteria are developed for the occurrence of azeotropes in binary nonelectrolyte systems for both isothermal and isobaric situations in terms of liquid‐phase activity coefficients at infinite dilution (γ∞). In the case of isothermal systems at temperature T, for a positive azeotrope, γ∞lvc≥ p*mvc/p*lvc where lvc refers to the less volatile component, mvc to the more volatile component, and p* to saturation vapour pressure at T; for a negative azeotrope, γ∞mvc≤ p*lvc/p*mvc. In the case of isobaric systems at pressure P, for a minimum‐boiling azeotrope, γ∞lvc(TBmvc) ≥ P/p*lvc(TBmvc), where TB refers to the boiling point at P; for a maximum‐boiling azeotrope, γ∞mvc (TBlvc) ≤ P/p*mvc(TBlvc). The criteria are also given in terms of the parameters of selected correlations for the excess molar Gibbs function (gE). Examples of the use of the criteria are provided. Various methods that generate values of γ∞ can be used in conjunction with the criteria, for example, in screening procedures.
Attainment of PI Achievable Performance for Linear SISO Processes with Deadtime by Iterative Tuning
Authors: Goradia D. B. , Lakshminarayanan S. , Rangaiah G. P. 
Published: July 2010

AbstractThis work presents a practical scheme to attain PI achievable performance (the performance achievable with a proportional integral (PI) controller) for linear SISO processes with dead time driven by stochastic disturbances. It uses a combination of a quantitative measure called Control Loop Performance Index (CLPI) and signature plots of the closed loop disturbance impulse response (IR) to arrive at PI achievable performance in an iterative manner. The proposed methodology requires only routine operating data and knowledge of the process delay, and its efficacy is illustrated through several case studies.
Recyclage d'un déchet, une boue rouge, comme catalyseur pour l'élimination des composés organiques volatils
Authors: Lamonier J. F. , Wyrwalski F. , Leclercq G. , Aboukaïs A. 
Published: July 2010

AbstractLe potentiel catalytique d'une boue rouge, déchet de la fabrication de l'alumine, a été évalué dans l'oxydation des COV et notamment du toluène. Séchée, elle contient essentiellement Al(OH)3 et Fe2O3. Il s'est avéré qu'une calcination de la boue rouge sous flux d'air à 500 °C conduit à la formation de Al2O3 et Fe2O3, oxydes qui sont actifs et sélectifs en CO2 dans la réaction d'oxydation du toluène. L'activité de la boue rouge peut être directement corrélée à la quantité de fer présente dans l'échantillon. En effet, la vitesse spécifique (par gramme de Fe2O3) de la réaction chimique en présence de la boue rouge est similaire à celle observée en présence d'un oxyde de fer Fe2O3 pur.
A Study on Hydrodynamics and Heat Transfer in a Bubble Column Reactor with Yeast and Bacterial Cell Suspensions
Authors: Kantarci Nigar , Ulgen Kutlu O. , Borak Fahir 
Published: July 2010

AbstractHydrodynamics and heat transfer experiments were carried out in a slurry bubble column with air‐water‐yeast cells and air‐water‐bacteria cells systems to investigate gas hold‐up, bubble characteristics and heat transfer coefficients with cell concentrations of 0.1% w/w and 0.4% w/w and superficial gas velocity up to 0.20 m/s. The gas hold‐ups and heat transfer coefficients were found to increase with increasing gas velocity and cell concentration. The heat transfer coefficients were higher at the centre of the column as compared to the near wall region. The development of empirical correlations to predict the heat transfer coefficient in two‐ and three‐phase systems was carried out with ±15% confidence interval at most.
Dispersion and Mass Transfer Effects on the Performance of an Immobilized Lipase Packed Bed Reactor During the Hydrolysis of Rice Bran Oil
Authors: Murty V. Ramachandra , Bhat Jayadev , Muniswaran P. K. A. , Sivasankaran S. 
Published: July 2010

AbstractThe performance of an immobilized packed bed reactor for the hydrolysis of rice bran oil has been investigated and can be well described by a dispersion model with an average standard deviation of 0.0388. Global mass transfer coefficients estimated using the model and experimental data ranged from 0.095‐0.482 min−1, depending on substrate flow rates. A dimensionless mass transfer correlation between the Sherwood number and the Reynolds number was obtained as NSh = 3.96 ×NRe2.07.
Improvement of the Fluidizability of Cohesive Powders through Mixing with Small Proportions of Group A Particles
Authors: Ajbar A. , Alhumazi K. , Asif M. 
Published: July 2010

AbstractThe gas fluidization behaviour of fine cohesive powders, classified as Geldart group C, is known to be characterized by cracks and channels leading to severe non‐homogeneities in the bed. Geldart group A particles, on the other hand, are known to show more homogeneous and regular fluidization behaviour. This paper studies the effects of the addition of small proportions of group A on the fluidization behaviour of a group C powder. Differential pressure fluctuations data at a sampling frequency of 200 Hz were recorded for two cases. In the first case, the bed contained only group C powder while in the second case small amounts of group A particles were added to the existing group C powder. Visual/image observations coupled with time series analysis showed that the addition of small proportions of group A particles substantially improved the fluidization behaviour of the bed even at low superficial gas velocities, leading to a more uniform fluidization. Evaluation of mean and standard deviations has shown the advantage of mixing the two powders as it allowed larger pressure fluctuations and smaller standard deviations. Power spectra, on the other hand, showed that unlike group C, for which fluctuations were small in magnitude and broadband in structure, the mixture showed stronger periodic behaviour as result of the attenuation of the small and rapid fluctuations caused by the flow of gas in the cracks and channels. Advanced methods such as the principal component analysis of the embedded trajectories allowed a quantitative comparison between the fluidization behaviour of the two systems.
Catalytic Activity of Copper Oxide Impregnated HZSM‐5 in Methanol Conversion to Liquid Hydrocarbons
Authors: Zaidi H. A. , Pant K. K. 
Published: July 2010

AbstractA number of CuO/HZSM‐5 catalysts have been studied in a small scale fixed bed reactor for the conversion of methanol to gasoline range hydrocarbons at 673 K and at one atmospheric pressure. All the catalysts were prepared by wet impregnation technique. The copper oxide loading over HZSM‐5 (Si/Al=45) catalyst was studied in the range of 0 to 9 wt%. XRD, surface area analyzer, metal trace analyzer, SEM techniques and TGA were used to characterize the catalysts. Incorporation of CuO onto HZSM‐5 zeolite significantly increased conversion and liquid hydrocarbon product yields. The major liquid products of the reactions were ethyl benzene, toluene, xylene, isopropyl benzene, ethyl toluene, trimethyl benzene and tetramethyl benzene. The maximum methanol conversion and hydrocarbon product yield was obtained at a copper oxide loading of 7 wt%. Effect of run time on conversion and product distribution was also investigated to compare the performance of these catalysts and coke on the catalyst was determined. Effect of space‐time and temperature on methanol conversion and products yield with 7 wt% CuO/HZSM‐5 has also been investigated and analyzed qualitatively.
Dissolution Rate of BTEX Contaminants in Water
Authors: Njobuenwu Derrick O. , Amadi Stephen A. , Ukpaka Peter C. 
Published: July 2010

AbstractThe BTEX group of contaminants consists of benzene, ethylbenzene, toluene, and three isomers of xylene. The dissolution rate, solubility, slick area and mass transfer coefficient were examined for the BTEX. The release of BTEXs into the environment is influenced by their fate and transport mechanisms. Thus, the fate and transport mechanisms are affected by the contaminant characteristics, which vary with the different BTEX compounds. A comprehensive model has been developed to simulate the molecular dissolution rate of BTEX contaminants in a natural water stream. The developed model modifies the work of Cohen et al. (1980) by considering the physicochemical properties of the BTEX compounds and physical processes relevant to the spreading of contaminants in the sea. The model shows that Benzene with greater solubility in water and dissolution coefficient has the largest dissolution rate while o‐xylene with the biggest density has the lowest dissolution rate because of its low fraction. The benzene dissolution rate is about 2.6, 20.6 times that of Toluene, ethylbenzene, respectively, but with a varying proportion with the xylenes. The model has been validated against the theories of mass transfer rate at the surface at appropriate surface area. The developed model can be found useful in prediction and monitoring the dissolution rate of contaminants in soil and water systems.
Assessment by Microscopy of the Coverage of Sludge Flocs by a Nano‐scale Surface Layer
Authors: Pazin Dorothy , Lott John N. A. , West M. Marcia , Leppard Gary G. 
Published: July 2010

AbstractFlocs are irregularly shaped suspended particles of complex structure and composition that occur naturally in aquatic systems. In water treatment facilities, the settling of flocs is extremely important. Transmission electron microscopy was used to quantify the formation of a nano‐scale surface layer on flocs from two laboratory bioreactors modelling a biological wastewater treatment facility. By comparing different floc populations, we demonstrated that flocs that settled quickly out of wastewater had a significant amount of this layer, whereas those with little nano‐scale surface layer had poor settling properties. This morphological feature of floc ultrastructure may permit engineering manipulations that promote floc settling.
Molecular Modelling—an Enabling Technology for Chemical Engineers
Authors: Choi Phillip 
Published: July 2010

AbstractThis article briefly describes the basic concepts involved in the two most commonly used molecular modelling methods—molecular dynamics (MD) and Monte Carlo (MC). The methods are particularly useful for studying structures at the length scale of nanometre. Two examples (both are on the study of the miscibility of polyolefin blends) are used to illustrate the techniques. It is demonstrated that it is the nano‐scaled structures formed by the segments of the constituent polyolefins that prevent them from mixing with each other. The examples also show that selection of specific method (MD or MC) depends on the nature of the problem in hand. In general, MC is more efficient than MD in terms of generating equilibrated structure while MD can provide information about the dynamics of a system. This is simply because MD requires the solution of equations of motion (a set of second order differential equations) while MC does not. Nonetheless, both methods need a reasonably accurate force field.
Thermal Blending Time Associated With a Charge of Hot Particles Added to a Fluidized Bed of Uniform Temperature
Authors: Brown W. A. , Pinchuk R. , Pinchuk M. , Diep J. , Weber M. E. , Kiel D. 
Published: July 2010

AbstractThe process of heat transfer between particles in a fluidized bed is important for many industrial fluidized bed processes. The problem associated with studying this phenomenon is the confounding effect of particle mixing on heat transfer. The work described here was undertaken to describe the process in which heat is added to a fluid bed process by adding a hot charge of particles to a colder fluidized bed. The rate of heat transfer in this instance can have a significant impact on performance of the fluid bed process, depending upon its application. Both the method of analysis and the results of the work are applicable to other fluidized bed processes, particularly those associated with the thermal upgrading of heavy oil.The method of data analysis, based on binomial statistics, allowed useful data to be extracted from a complex system without the need for a large number of experiments. The analysis also allowed for some assessment of the relative importance of mixing and heat transfer, which has not been possible with other approaches. The results of the experiments were further explored using a bubbling bed model that incorporated both heat transfer and solids mixing. This allowed for the formation of a conceptual model, validated by the experimentation, that explains the relative functions of the two transfer processes in the dispersion of heat from a hot charge of particles to the bulk of a fluidized bed.
On Determination of Azeotrope Coordinates from gE for Binary Isothermal and Isobaric Systems
Authors: Missen Ronald W. 
Published: July 2010

AbstractA relatively simple procedure is described to calculate the coordinates, temperature (Taz), pressure (Paz), and composition (x1az), of an azeotrope (for either an isothermal or isobaric binary system at low pressure and with a single or double homogeneous azeotrope) from an expression for the liquid‐phase excess molar Gibbs function (gE). General results are based on (∂gE/∂x1)az = RTaz ln[p2*(Taz)/p1*(Taz)], and Paz = (γ1p1*)az = (γ2p2*)az, where R is the gas constant, p* is saturation vapour pressure, and γ is liquid‐phase activity coefficient. Specific results are given for the Redlich‐Kister, van Laar, Wilson, and NRTL equations. Numerical examples are provided for both an isothermal and an isobaric system. The procedure provides a means to obtain azeotrope coordinates that are consistent with a gE expression obtained either from experimental data or from a model. It is applicable to polyazeotropy, whereas the criteria given previously are generally not applicable to polyazeotropy.
Optimum Production and Characterization of Thermostable Amylolytic Enzymes from B. stearothermophilus GRE1
Authors: Hossain S. M. Z. , Haki G. D. , Rakshit S. K. 
Published: July 2010

AbstractOptimum production of extracellular, thermostable amylolytic enzymes (α and β‐amylase) by a newly isolated bacterium, Bacillus stearothermophilus, was investigated in a batch bioreactor. Starch and lactose at 1.0% and 3.0% (w/v) respectively were found to be optimum for maximum enzyme production. Optimization of cultural conditions (pH 7.0 and temperature 45°C) resulted in high bacterial specific growth rate (0.64 h−1), yielding 2.20 gL−1 biomass, 11.43 UmL−1 α‐amylase and 10.04 UmL−1 of β‐amylase. Hydrolysis of native starches from wheat, cassava, corn and potato at 60°C using the crude enzyme showed 60‐80% saccharification with potato starch showing the least and wheat starch showing the greatest hydrolysis. The Km and Vmax values of the crude α‐amylase for starch were 4.78 mg starch/mL and 6.67 mg/mL.min respectively.
Dependence of Holdup on Height in a Pulsed Plate Column Based on Binary Liquid‐Liquid Equilibrium Data
Authors: Montazer‐Rahmati M. M. , Safdari S. J. , Akhgari H. 
Published: July 2010

AbstractHoldup has been measured at various frequencies, amplitudes, continuous and dispersed phase flow rates for binary systems in a pulsed plate column capable of providing samples at various heights. The binary systems have been so selected as to cover a wide spectrum of interfacial tensions. Dispersed phase holdup was found to increase with height in a logarithmic fashion at conditions away from the flooding point and to become almost invariant with height near flooding conditions. The interfacial tension of the binary system has a large effect on the dispersed phase holdup. In systems having low interfacial tension, a small increase in any of the parameters can increase the holdup significantly and lead to flooding. In systems having high interfacial tension, on the other hand, variations in system parameters do not affect system performance significantly.
Dynamic Modelling and Prediction of Cytotoxicity on Microelectronic cell Sensor Array
Authors: Huang Biao , Xing James Z. 
Published: July 2010

AbstractA real‐time cell electronic sensing (RT‐CES) system has been used for label‐free dynamic measurements of cell responses to toxicant. Cells are grown onto the surfaces of the microelectronic sensors. Changes in cell number expressed as cell index (CI) have been recorded on‐line as time series. The CI data are used for dynamic modelling or parameter estimation for cell cytotoxicity process. We consider two dynamic modelling approaches, namely data‐based system identification and first principle modelling. It is shown that data‐based system identification can provide a quick solution for the cytotoxicity dynamic models and is effective for short‐term predictions. It, however, can be poor for long‐term predictions, particularly if there is no output correction, i.e., when the model is used for simulation. In view of this, the first principle modelling approach by considering fundamental physical principles such as toxicant transport is explored. For long‐term prediction or simulation, the prediction performance for some of cytotoxicity process is dramatically improved using the models obtained from the latter approach. This happens only if the underlying mechanism is truly understood. Through several cytotoxicity modelling and validation studies, it is shown that the black box modelling and first principle modelling both should be considered in challenging modelling problems such as the cytotoxicity. Pros and cons of the two modelling approaches are discussed.
Near Wall Studies of Pulp Suspension Flow Using LDA
Authors: Pettersson A. Johan , Wikström Tomas , Rasmuson Anders 
Published: July 2010

AbstractA detailed study of the flow behaviour in the near wall region of pulp suspensions up to 4.7% have been performed using Laser Doppler Anemometry (LDA) in pipe flow. Axial mean velocity profiles show a distinct plug flow and an increase of the plug region as the flow rate decreases and fibre concentration increases.An attempt is made to relate the LDA data‐rate to fibre concentration, which indicates a dilution region at 1‐2 mm from the wall that is larger than the annulus region. The dilution region increases with increasing flow rate, decreasing concentration and when using longer pulp fibres.
A New Group Contribution Method based on Equation of State Parameters to Evaluate the Critical Properties of Simple and Complex Molecules
Authors: Valderrama José O. , Alvarez Víctor H. 
Published: July 2010

AbstractA new group contribution method to evaluate the critical properties (temperature, pressure and volume) is presented and applied to estimate the critical properties of biomolecules. Similar to other group contribution methods, the one proposed here divides the molecule into conveniently defined groups and evaluates the properties as the sum of the different contributions according to a specified model equation for each of the properties. The proposed method consists of a one‐step calculation that uses simple model equations and does not require additional data besides the knowledge of the structure of the molecule, except for isomers. For these substances the normal boiling temperature, the molecular mass and the number of atoms in the molecule are used to distinguish among isomers. The method is applicable to high molecular weight compounds, as most biomolecules and large molecules present in natural products.
Kinetics of Liquid‐Phase Hydrogenation of Iso‐valeraldehyde to Iso‐amyl Alcohol Over A Ru/Al2O3 Catalyst
Authors: Tike Manoj A. , Mahajani Vijaykumar V. 
Published: July 2010

AbstractThe liquid‐phase catalytic hydrogenation of iso‐valeraldehyde to iso‐amyl alcohol was studied in a slurry reactor. The kinetics of liquid‐phase hydrogenation of iso‐valeraldehyde over a 5% Ru/Al2O3 catalyst was studied in the range of temperature 373‐393 K and H2 pressure 0.68‐2.72 MPa using 2‐propanol as the solvent. The selectivity to iso‐amyl alcohol was 100%. The kinetic data were analyzed using a simple power law model. A single site Langmuir‐Hinshelwood type model suggesting dissociative adsorption of hydrogen and surface reaction as the rate‐controlling step provided the best fit of the experimental data. The catalyst could be reused thrice without any loss in activity.
Influence of Non‐Condensable Gases on the Dynamic Behaviour of an Auto‐Refrigerated CSTR Polymerization Reactor
Authors: de Toledo Eduardo Coselli Vasco , Martini Rogerio Favinha , Maciel Maria Regina Wolf , Filho Rubens Maciel 
Published: July 2010

AbstractA polymerization reactor connected to a semi‐flooded horizontal condenser is presented. A model of the process was developed, taking into account the influence of non‐condensable gases in the system. The results obtained show that the model developed was able to reproduce the major dynamic characteristics, even with the presence of non‐condensable gases. It is shown that the non‐condensable gases have great influence on the reactor state, which never reaches a steady‐state; these gases accumulate in the system, increasing the pressure and temperature, and reducing the area of contact and the mass of liquid, therefore needing to be purged regularly, otherwise the system will collapse.
Influence of Polymer Type and Structure on Polymer Modified Asphalt Concrete Mix
Authors: Hussein Ibnelwaleed A. , Wahhab Hamad I. Al‐Abdul , Iqbal Mohammad H. 
Published: July 2010

AbstractTwo low‐density polyethylene (LDPE) resins and two ethyl vinyl acetate (EVA) polymers were used to modify asphalt binder, and then mixed with asphalt concrete according to Marshall Method of mix design (ASTM D 1559). Effect of weight average molecular weight (Mw) of LDPE and vinyl acetate (VA) content of EVA was studied by performing Marshall Stability, moisture susceptibility (AASHTO T 283‐89), resilient modulus (MR) and permanent deformation (rutting) tests. EVA with low VA content showed lower stability loss in Marshall Stability test and improved resistance in moisture susceptibility test in comparison to hot mix asphalt concrete mix (HMA) and other polymer modified asphalt concrete mixes (PMAMs). Higher MR and better rutting resistance were observed for PMAMs than that of HMA. This elastic behaviour of modified asphalt correlates very well with the MR and rutting resistance properties of PMAM.
Reaction Engineering Studies on the Biodegradation of Anthracene on Bioremediation of Diesel Contaminated Soil Using Acinetobacter sp. (ATCC No. 14293)
Authors: Roy Ruma , Bhattacharya Pinaki , Chowdhury Ranjana 
Published: July 2010

AbstractIn the present investigation bio‐degradation of anthracene, a polyaromatic hydrocarbon, from its simulated mixture in methanol, has been studied using a monoculture strain, (Acinetobacter sp. (ATCC No. 14293)), within the concentration range 500‐800 mg/dm3. In a separate attempt bioremediation of diesel contaminated soil to reduce total aromatic content using the same bacterial strain has been carried out. The main emphasis of this investigation is to understand the complex reaction engineering behaviour involved in both the above bioprocess systems. It is observed that while Monod's classical substrate uninhibited model can be used for simulation purpose for the biodegradation of anthracene, the reaction engineering behaviour of the bioremediation of soil can be expressed by coupling Monod's classical equation with first order cell decay rate. In both the cases the concerned intrinsic kinetic parameters have been evaluated.