bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of the peracetic acid decomposition: Part II: pH effect and alkaline hydrolysis
Authors: Yuan Z. , Ni Y. , Van Heiningen A. R. P. 
Published: March 2009

AbstractThe effect of pH on the decomposition of peracetic acid in an aqueous solution was studied. It was found that three potential reactions, namely i) the spontaneous decomposition, ii) the hydrolysis and iii) the transition metal catalysed decomposition, are responsible for the consumption of peracetic acid. The spontaneous decomposition reaches its maximum at pH 8.2, while both the hydrolysis and metal ion catalysed decomposition increase as the pH increases. At pH 10.5 and higher, the hydrolysis becomes dominant when the metal ion catalysed decomposition is minimized by the addition of DTMPA. The kinetics of the peracetic acid hydrolysis was developed, which can very well predict the development of peracetic acid and hydrogen peroxide during the decomposition reaction.
Gas—liquid mass transfer in pulp suspension mixing operations
Authors: Bennington C. P. J. , Owusu G. , Francis D. W. 
Published: March 2009

AbstractThe rate of mass transfer from the gas to water phases was measured in a commercial, high‐shear, laboratory mixer under conditions typical of medium‐consistency bleaching. The gas—liquid volumetric mass transfer coefficient, kLa, was measured using the cobalt‐catalyzed sulfite oxidation technique. Suspensions of fully‐bleached kraft pulp and synthetic nylon fibres were used, with mass transfer rates measured over a range of suspension compositions and mixer operating conditions. In the presence of pulp fibre, mass transfer rates were significantly reduced over the comparable water cases. The same dramatic decrease in mass transfer was not observed for the nylon suspensions, although kLa did decrease with increasing suspension concentration. Comparison of this data with that obtained from ozone bleaching experiments confirmed that at medium‐consistency gas—liquid mass transfer controls ozone bleaching.
Removal of contaminants from recirculated white water by ultrafiltration and/or biological treatment
Authors: Elefsiniotis P. , Hall E. R. , Johnson R. M. 
Published: March 2009

AbstractThis study investigated the potential of ultrafiltration technology and/or biological treatment to remove contaminants such as total dissolved solids (TDS), chemical oxygen demand (COD), total organic carbon (TOC), and resin and fatty acids (RFAs) from recirculated white water. Batch ultrafiltration experiments indicated that TDS, soluble COD, and TOC removal efficiencies were affected by membrane molecular weight (molar mass) cut‐off, but were independent of the operating temperature, in the 20 to 60°C range. Except for fatty acids, where average removals exceeded 90%, the separation efficiency of the process for all other parameters (TDS, soluble COD, TOC, and resin acids) was moderate, ranging from 10 to 41%. Biological treatment using a sequencing batch reactor (SBR) unit was very effective in removing RFAs, TOC, total and soluble COD. Furthermore, ultrafiltration of the biologically treated process water resulted in significant additional TDS, soluble COD, and TOC removal.
Phenolic compounds from vacuum pyrolysis of wood wastes
Authors: Pakdel H. , Roy C. , Amen‐Chen C. , Roy C. 
Published: March 2009

AbstractVarious softwood and hardwood bark residues, primary sludges and softwood sawdust residues were processed by vacuum pyrolysis in a laboratory scale batch reactor. The pyrolysis oil, water, charcoal, and gas were recovered and analyzed. The pyrolysis oils were analyzed in details for their content in phenolic compounds after derivatization to their acetyl derivatives. The influence of temperature, heating rate, feedstock bed thickness, particle size and feedstock water pretreatment on the yield of phenols was investigated. The highest yield of phenols was obtained when hardwood bark was soaked in water for 48 hours and pyrolyzed at a temperature of 450°C and a heating rate of 10°C/min. Pyrolysis performance was evaluated in terms of total phenolic yield and composition.
Micro‐ and macroscopic aspects of polymer bonded paper
Authors: Jonasson R. G. , Henry D. 
Published: March 2009

AbstractThe bonding of polymers was examined using analogues of commercial adhesive which were selected so that they could be readily detected by surface microanalytical techniques including scanning electron microscopy, X‐ray photoelectron spectroscopy and secondary ion mass spectrometry. When reagents were added to the pulp prior to handsheet preparation, epoxides but not isocyanates, were found to adhere to cellulose and wood fibers by polymerizing with themselves. That is, epoxides polymerized to form gels, which then adhered to the fibers. To test this hypothesis, handsheets were treated subsequently with solutions of pre‐formed polymers. In the case of both polyvinylchloride and cellulose acetate, the tensile breaking length and burst index of treated handsheets increased significantly compared with the controls. No surface analytical, or bulk property data was found in this study to demonstrate covalent bonding of adhesives to cellulose or wood fibers. This means that adhesives should be readily extracted from recycled paper with appropriate organic solvents.1
Kinetics of the heterogeneous catalytic decomposition of methane
Authors: Kristyan Sandor 
Published: March 2009

AbstractExperiments have clearly demonstrated that dissociation of CH4 on (supported) metal catalyst (e.g. Pt, Ru, Rh, Ir, Pd) occurs to give hydrogen, a small amount of ethane and surface carbonaceous species. For this catalytic decomposition of methane and its conversion into higher hydrocarbons (especially to ethane and surface carbon) model has been developed to investigate the kinetics. Rate constants of the elementary steps have been estimated. The problem with experimental data (especially for the surface species CHm‐s) is also treated for the sake of future improvement in the kinetics studies. A comparison with catalytic hydrogenolysis of ethane kinetics is also outlined.
Pressure drops in gas—liquid flow in a 15 cm reciprocating platecolumn
Authors: Baird M. H. I. , Rao N. V. Rama 
Published: March 2009

AbstractTime‐averaged pressure drops have been measured in a 15 cm internal diameter reciprocating plate column, using the water/air system under conditions of cocurrent, countercurrent and single phase (water) flow. The reciprocation frequency was varied from 1 to 4 Hz, while the stroke (peak to trough amplitude) was set at 2.54 cm. Two types of perforated plate were used, having perforation diameters 14.3 and 6.35 mm.Under single phase flow conditions, the pressure drops were in agreement with an earlier model due to Noh and Baird (1984). Under cocurrent conditions the gas flow had the effect of increasing the pressure drop, particularly at low reciprocation rates; this was interpreted in terms of enhanced circulation velocities in the liquid phase. In countercurrent flow the pressure drop was also affected by bubbles clustering at the plates.
Liquid circulation and mixing in an inclined bubble column
Authors: Lu George Z. , Bittorf Kevin , Thompson Brad G. , Gray Murray R. 
Published: March 2009

AbstractGas and liquid velocities were measured in an inclined rectangular column, at inclinations in the range 0−45° and superficial gas velocities of 0.002 to 0.12 cm/s. Liquid circulation was also characterized by measuring the time to mix a pulse of salt solution in the column. Inclining the column by up to 10° from the vertical induced a drastic change in behavior, from a bubble column with evenly distributed gas bubbles to a segregated system with rapid liquid circulation pumped by rising gas bubbles. The liquid velocities in the inclined column ranged from 10 to 50 times the superficial gas velocity. Further inclination of the column in the range of 10−45° had little effect on liquid velocity or mixing time. A compartmental model for the recirculating liquid flow matched the observed mixing times, but predicted oscillations in tracer concentration which were not detected in experiments.
Absorption with zero and Pseudo‐Zero order chemical reaction
Authors: Prisciandaro Marina , Pepe Francesco 
Published: March 2009

AbstractIn this paper the equations modeling absorption accompanied by a zero order reaction and by a pseudo‐zero order reaction in the liquid phase are analytically solved by using the film theory. For the cases of both zero and pseudo‐zero order reaction the analysis leads to conclusion that three regimes of the process need to be considered; the three corresponding reactant concentration profiles are developed: for low values of the Hatta number (Ha), the reaction does not go to completion in the liquid film, and therefore the reactant concentration in the liquid bulk is not zero; for intermediate values of Ha, the concentration becomes zero at the film‐bulk interface, but its gradient is not zero so that an instantaneous reactant consumption takes place at such interface; for higher values of Ha the reactant concentration becomes zero in the liquid film. The dependence of the enhancement factor on Ha is also determined, allowing the description of transition from the slow reaction regime to the fast and instantaneous reaction regime.
Effect of process variables on scale formation in steel reheating
Authors: Ormerod R. C. , Becker H. A. , Grandmaison E. W. , Pollard A. , Sobiesiak A. 
Published: March 2009

AbstractVariables affecting the high temperature oxidation of steel were investigated using an experimental design strategy. The experimental methods included continuous mass‐gain measurement to characterize the oxidation kinetics in terms of parabolic rate constants. A Morris and Mitchell (1983) eleven‐run experimental design was used to identify main effects and interactions among seven independent variables (oxidation temperature, steel grade, steel surface condition, sample history and gas composition: H2O, O2 and CO2). The levels of these variables were chosen to reflect industrial steel reheat operations. The use of this type of strategy in assessing the effect of variables at an intermediate stage in an experimental program is also demonstrated.
Étude des conditions opératoires optimales de synthèse du 2‐furyl oxirane à l'aide de modèles empiriques et mécanistiques
Authors: Uhlemann Jens , Borredon Elisabeth , Gaset Antoine 
Published: March 2009

AbstractLa détermination des conditions opératoires optimales de la synthèse du 2‐furyl oxirane effectuée en transfert de phase solide—liquide faiblement hydraté dans deux domaines expérimentaux différents (différentes granuloméres de la base; différents sels de sulfonium) a été realisée à l'aide de deux méthodologies d'optimisation. La première méthodologie est basée sur l'utilisation de modèles empiriques (plans d'expériences) et la seconde sur l'utilisation de modèles mécanistiques (“modélisation de tendances”). La comparaison des résultats d'optimisation permet d'apprécier les avantages et les inconvénients relatifs aux deux méthodologies. Les rendements optimaux dans les deux domaines expérimentaux sont respectivement de 89 et de 95.5%.
3‐D hydrodynamics generated in a stirred vessel by a multiple‐propeller system
Authors: Baudou C. , Xuereb C. , Bertrand J. 
Published: March 2009

AbstractThe aim of this study is to optimize the position and the number of propellers in a non‐standard tall vessel. Laser sheet flow visualization experiments were carried out for selected geometrical arrangements which produced stable flow patterns and good transport between the propellers. Four double‐propeller arrangements corresponding to frequent industrial cases and a three‐propeller system have been chosen. Comparison of LDA measurements in the r‐z plane, dimensionless global parameters NQp, Ntm, Np, Ep and spatial distribution of local energy dissipation rate ϵ shows that a three‐propeller system is the most efficient.
Application of random‐search algorithm for regression analysis of catalytic hydrogenations
Authors: Belohlav Zdenek , Zamostny Petr , Kluson Petr , Volf Jiri 
Published: March 2009

AbstractA short review of the works concerning parameter estimation in kinetic experiments was performed. An adaptive random search algorithm was applied to evaluate the parameters and parameter confidence intervals of Langmuir‐Hinshelwood models. The kinetic parameters were determined using the Box ‐ Draper criterion. The parameter confidence regions were found by using the likelihood ratio. Three heterogeneously catalyzed hydrogenations were studied.
Power and mean flow characteristics in mixing vessels agitated by hyperboloid stirrers
Authors: Pinho F. T. , Piqueiro F. M. , Proençla M. F. , Santos A. M. 
Published: March 2009

AbstractThe mean flow and energy consumption in vessels powered by hyperboloid stirrers was investigated. The Newton number followed an inverse linear law for Reynolds numbers below approximately 200, which had values more than twice higher the corresponding Newton number for a standard Rushton turbine. At high Reynolds number flows the Power number varied between 0.5 for a D/T = 0.78 impeller to 0.95 for a D/T = 0.24 impeller, as compared to a value of 5 for the standard Rushton stirrer, and to values of 0.31 and 1.58 for the Chemineer and Prochern hydrofoils. The power consumption did not change with the fluid height and was double for the double‐stack configuration. The shear ribs below the impeller were the main contributor to the increased energy loss relative to a non‐shear ribbed impeller and the small clearance had no major effect upon the power consumption. For the D/T= 1/3 hyperboloid stirrer the flow in the whole tank was rather gentle, defining a circulation number of 0.57, thus leading to a circulation efficiency more than 7 times lower than that of the hydrofoils.
Exit effects in circulating fluidized bed risers
Authors: Pugsley Todd , Lapointe Diane , Hirschberg Bernd , Werther Joachim 
Published: March 2009

AbstractThe relative influence of smooth and abrupt exit configurations on the axial pressure drop profile in Circulating Fluidized Bed (CFB) risers has been investigated. Experiments were performed with sand and FCC catalyst in two cold model CFBs of 0.1 metre and 0.2 metre riser diameter. The influence of the abrupt exit on the profile was observed to extend all the way to the base of the larger diameter riser for sand. However, the abrupt exit influenced only the final 1.5 to 2 metres of the riser length for the case of sand in the narrow diameter riser. When FCC catalyst was circulated, the effect of the abrupt configuration was seen only in the upper portion of the riser, irrespective of the riser diameter. A simple empirical modification to the model of Pugsley and Bermti (1996) provides a good description of the axial pressure drop profiles for the abrupt exit configurations, with the exception of the case of sand in the 0.2 metre diameter riser. This discrepancy is attributed to the lack of fully developed flow in the larger riser.
The Interaction of solute transfer, contaminants and dro break‐up in rotating disc contactors: Part II. The coupling of the mass transfer and breakage processes via interfacial tension
Authors: Cauwenberg Veerle , Degrève Jan , Slater Michael J. 
Published: March 2009

AbstractIn order to investigate the influence of solute transfer and of surface active agents on the drop breakage process in liquih liquid extraction columns, their effect on the interfacial tension has to be studied in detail. The difficulty encountered is that the interfacial tension during solute transfer continuously changes and that no simple apparatus is commercially available which can measure these varying interfacial tension values. An attempt has been made here to theoretically predict them. The equations developed to predict the interfacial tension variation can be combined with a model for the breakage process and hence drop size distributions can be calculated from stage to stage. Applying a new combined film mass transfer coefficient model which takes into account the effect of contaminants, single drop extraction performance has been calculated for simplified conditions of constant bulk concentration in the continuous phase. Calculated efficiencies have been compared with experimental data and a good simulation of contaminant effects and dependency on drop size has been found. The calculations were restricted to low dispersed phase hold‐up values, so that coalescence effects could be ignored. This work provides the required support for a procedure to be applied to counter‐current flow extraction columns.
Kinetics of carbon dioxide and methane hydrate formation
Authors: Malegaonkar Mahendra B. , Dholabhai Pankaj D. , Bishnoi P. Raj 
Published: March 2009

AbstractExperimental data on the kinetics of carbon dioxide hydrate formation and its solubility in distilled water are reported. The experiments were carried out in a semi‐batch stirred tank reactor at nominal temperatures of 274, 276 and 278 K and at pressure ranging from 1.59 to 2.79 MPa for the kinetics experiments and at pressure ranging from 0.89 to 2.09 MPa for the solubility experiments. A minor inconsistency in the kinetic model developed by Englezos et al. (1987a) was removed and the model was modified to determine the intrinsic kinetic rate constant for carbon dioxide hydrate formation. The same model was also used to re‐determine the intrinsic kinetic rate constant for methane hydrate formation. The model is based on the crystallization theory coupled with the two‐film theory for gas absorption in the liquid phase. The Henry's constant (H) and apparent dissolution rate constant (KLa) required in the model were determined using the experimental solubility data. The kinetic model describes the experimental data very well. The kinetic rate constant obtained for the carbon dioxide hydrate formation was found to be higher than that for methane.
Gas—liauid mass transfer in three‐phase stirred tank reagors: Newtonian and non‐newtonian fluids
Authors: Rawase Yoshlnori , Araki Takae , Shimzu Kazuhiro , Miura Hideki 
Published: March 2009

AbstractGas—liquid mass transfer has been investigated in gas—liquid‐solid three‐phase stirred tank reactors with Newtonian and non‐Newtonian liquids. Volumetric mass transfer coefficients and gas hold‐ups were measured in a 0.2 m i.d. stirred tank reactor and the effects of low‐density polymeric particles (ρs, =1030 and 1200 kg/m3; up to 15 vol%) on gas—liquid mass transfer were examined. The volumetric mass transfer coefficients in water were found to decrease due to the presence of solid particles at constant impeller speed and superficial gas velocity. On the other hand, solids loading led to higher mass transfer rates in non‐Newtonian carboxymethyl cellulose aqueous solutions. Our previously proposed model for mass transfer in gas—liquid two‐phase systems was extended to gas—liquid—solid three‐phase systems. Reasonable agreement was found between the predictions of the proposed model and the experimental data.
Comments on modelling the diffusion‐controlled adsorption of surfactants
Authors: Campanelli John R. , Wang Xiaohong 
Published: March 2009

AbstractIn this study, dynamic interfacial tension data are obtained with a drop volume tensiometer at the mineral oil‐water interface for Triton X‐100 dissolved in the water phase, and for Span 80 dissolved in the oil phase. Surfactant adsorption is modelled under diffusion‐controlled conditions using either long or short diffusion time approximations. A dimensionless parameter relating adsorption time, ta, to a characteristic diffusion time of each surfactant, tD, is introduced in order to determine the general applicability of the diffusion approximations. In the case of Triton X‐100, the long time approximation is valid, and the ratio of ta/τD is found to be much greater than one. In the case of Span 80, the short time approximation provides a good fit to the experimental data, and the ratio ta/τD is found to be on the order of unity or less. A consideration of experimental data found in the literature for other surfactants leads to the general conclusion that the ratio ta/τD is useful in characterising diffusion‐controlled adsorption of surfactants.
Cold enzyme hydrolysis of wheat starch granules
Authors: Textor Steven D. , Hill Gordon A. , Macdonald Douglas G. , Denis Earl St. 
Published: March 2009

AbstractThree α‐amylase enzymes were used to hydrolyze wheat starch granules suspended in water below the gelatinization temperature. The rates of hydrolysis were determined at various temperatures, pH, enzyme and starch concentrations. Barley amylase was found to be the “best” enzyme when used at pH 4.5, 45°C and starch and enzyme concentrations of 30 and 8 mg/mL respectively. It was found that under these conditions, 98% of the starch granules were hydrolyzed in 3 hours, the same amount of time used in the industrial cooking process of soluble starch. Starch particles were observed to be attacked at specific points on the surface and then hydrolyzed from the inside‐out. Some granules were hydrolyzed at a very fast rate with a first order rate constant estimated to be 40 h−1; but most granules were hydrolyzed slowly according to the Michaelis‐Menten model and the best fit parameters were found to depend on enzyme type, pH and temperature.
The marangoni effect and enhanced oil recovery Part 1. Porous media studies
Authors: Lyford Paul A. , Pratt H.R.C , Shallcross David C. , Grieser Franz 
Published: March 2009

AbstractThe use of partitionable solutes, e.g., aliphatic alcohols, to enhance the recovery of trapped oil in reservoir rock, has been simulated using a ballotini‐packed column initially flooded with kerosene, and subsequently lowered to an irreducible value by a water drive. Introduction of a “slug” of an alcohol effected an increased recovery, with n‐propanol and sec‐butanol giving the highest yields. Previous workers attributed such increased recovery to the formation of a “soluble front”, in which both oil and connate water are completely dissolved. However, we obtained similar recoveries using slugs with initial compositions lying on the miscibility boundary, which could not form soluble fronts. It was therefore concluded that Marangoni‐induced oscillation of the trapped drops is the more likely explanation of the enhanced recovery.
Derivation of a control oriented low order model of the dynamics of an infrared oven for the continuous drying of a thin sheet of material
Authors: Dhib Ramdhane , Thérien Normand , Broadbent Arthur Douglas 
Published: March 2009

AbstractA model consisting of three partial non‐linear differential equations for describing the humidity and temperature of a thin sheet of material and of the temperature of the air flow as a function of time and position in an infrared dryer was reduced to a model more adaptable to direct digital control. To begin with the original model was discretized along the length of the dryer and then linearized. Models of orders ranging from 12 to 72 were analyzed for controllability and observability. Using Moore's method, the models thus obtained were further reduced to a controllable state space model of order 5 that produced satisfactory results and for which stability was preserved. Simulated open loop responses of the reduced model to discrete perturbations in emitter electrical power, inlet humidity and velocity of the web, produced satisfactory dynamic and steady‐state responses when compared to responses of the original model subjected to similar perturbations. The steady‐state responses showed absolute errors for humidity and temperature of the web less than 1.3% [g water/100 g] and 2.2°C, respectively.