Catalogue en ligne Bibliothèque Ecole Nationale Polytechnique d'Alger

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 9054–9060

Titre :	Prediction of the θ(UCST) of polymer solutions : a quantitative structure−property relationship study
Type de document :	texte imprimé
Auteurs :	Gharagheizi, Farhad, Auteur ; Sattari, Mehdi, Auteur
Année de publication :	2009
Article en page(s) :	pp. 9054–9060
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Polymer solutions Thermodynamic properties Quantitative structure−property relationship technique θ(UCST)
Résumé :	One of the industrially important thermodynamic properties of polymer solutions is the upper critical solution temperature at the limit of infinite chain length of polymers, which is used to realize the usage limits of polymer solutions; this property is denoted as the θ(UCST). In this study, the quantitative structure−property relationship technique (QSPR) was used to correlate the θ(UCST) of polymer solutions. Based on molecular descriptors calculated from the chemical structures of the polymer and the solvent, a nine-parameter multilinear equation was obtained. This correlation can predict the θ(UCST) of 107 polymer solutions with a mean relative error of 6.12% and squared correlation coefficient of 0.912.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie9000426

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 9049–9053

Titre :	Modeling of mercury oxidation and adsorption by cupric chloride-impregnated carbon sorbents
Type de document :	texte imprimé
Auteurs :	Sang-Sup Lee, Auteur ; Joo-Youp Lee, Auteur ; Soon-Jai Khang, Auteur
Année de publication :	2009
Article en page(s) :	pp. 9049–9053
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Cupric chloride-impregnated activated carbon sorbents Mercury oxidation Mathematical modeling
Résumé :	Cupric chloride-impregnated activated carbon sorbents (CuCl2-ACs) showed good performance in Hg0 oxidation and adsorption in previously published entrained-flow test results. In addition, our previous studies indicated that Hg0 is oxidized by CuCl2-ACs and the resultant oxidized mercury is readsorbed onto the sorbents. This study conducted mathematical modeling to interpret these previous results and better understand the Hg0 oxidation and adsorption mechanism of CuCl2-ACs. As a result, the mathematical modeling results confirmed that Hg0 oxidation by CuCl2-ACs is determined by the injection level of CuCl2 impregnated onto the sorbents. An increase in CuCl2 loading in CuCl2-ACs was found to increase Hg0 oxidation but very slightly increased Hg adsorption because an increase in CuCl2 loading decreased the active CuCl2-free carbon sites available for the readsorption of resultant oxidized mercury on the surfaces and inside the pores.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900619v

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 9049–9053

Titre :	Modeling of mercury oxidation and adsorption by cupric chloride-impregnated carbon sorbents
Type de document :	texte imprimé
Auteurs :	Sang-Sup Lee, Auteur ; Joo-Youp Lee, Auteur ; Soon-Jai Khang, Auteur
Année de publication :	2009
Article en page(s) :	pp. 9049–9053
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Cupric chloride-impregnated activated carbon sorbents Mercury oxidation Mathematical modeling
Résumé :	Cupric chloride-impregnated activated carbon sorbents (CuCl2-ACs) showed good performance in Hg0 oxidation and adsorption in previously published entrained-flow test results. In addition, our previous studies indicated that Hg0 is oxidized by CuCl2-ACs and the resultant oxidized mercury is readsorbed onto the sorbents. This study conducted mathematical modeling to interpret these previous results and better understand the Hg0 oxidation and adsorption mechanism of CuCl2-ACs. As a result, the mathematical modeling results confirmed that Hg0 oxidation by CuCl2-ACs is determined by the injection level of CuCl2 impregnated onto the sorbents. An increase in CuCl2 loading in CuCl2-ACs was found to increase Hg0 oxidation but very slightly increased Hg adsorption because an increase in CuCl2 loading decreased the active CuCl2-free carbon sites available for the readsorption of resultant oxidized mercury on the surfaces and inside the pores.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900619v

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 9045–9048

Titre :	Phase equilibria of clathrate hydrates of cyclopentane + hydrogen sulfide and cyclopentane + methane
Type de document :	texte imprimé
Auteurs :	Amir H. Mohammadi, Auteur ; Richon, Dominique, Auteur
Année de publication :	2009
Article en page(s) :	pp. 9045–9048
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Hydrogen sulfide Cyclopentane Water Methane Isochoric pressure-search method
Résumé :	In this work, experimental hydrate dissociation data for the hydrogen sulfide + cyclopentane + water and methane + cyclopentane + water systems are reported in the temperature ranges of 295.4−310.0 K and 284.8−299.3 K, respectively. The experimental data were generated using an isochoric pressure-search method. The hydrate dissociation data for the methane + cyclopentane + water system are compared with some selected experimental data from the literature, and the acceptable agreement demonstrates the reliability of the experimental method used in our work. The experimental data for both measured systems are finally compared with the corresponding literature data in the absence of cyclopentane to study its hydrate promotion effects.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900376p

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 9040–9044

Titre :	Chemically enhanced separation of H2S04/HI mixtures from the bunsen reaction in the sulfur−iodine thermochemical cycle
Type de document :	texte imprimé
Auteurs :	Vincenzo Barbarossa, Auteur ; Giuseppina Vanga, Auteur ; Maurizio Diamanti, Auteur
Année de publication :	2009
Article en page(s) :	pp. 9040–9044
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Sulfuric acid Hydriodic acid Sulfur dioxide
Résumé :	The Bunsen reaction identifies the chemical formation of sulfuric acid and hydriodic acid when sulfur dioxide is oxidized by molecular iodine in aqueous solutions. This reaction occurs spontaneously in a temperature range of 293−373 K and is one of the three steps of the sulfur−iodine thermochemical cycle capable of producing hydrogen from water. In order to attain this, the handling of the H2SO4/HI mixture is crucial for the thermal decompositions which follow. In our study, we propose an innovative way to separate the acids by using an intermediate insoluble sulfonic acid which forms during the process. This procedure results in two main advantages: (1) the common problem of large quantities of iodine in excess is avoided and (2) less water is used.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie9002427

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 9034–9039

Titre :	Deep oxidative desulfurization of fuel oils catalyzed by decatungstates in the ionic liquid of [Bmim]PF6
Type de document :	texte imprimé
Auteurs :	Huaming Li, Auteur ; Xue Jiang, Auteur ; Wenshuai Zhu, Auteur
Année de publication :	2009
Article en page(s) :	pp. 9034–9039
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Fuel oils Tetrabutylammonium decatungstate Tetramethylammonium decatungstate Benzyltriethylammonium decatungstate Extractive catalytic oxidative desulfurization Ionic liquid
Résumé :	Three decatungstates with short carbon chains as the cations, such as tetrabutylammonium decatungstate ([(C4H9)4N]4W10O32), tetramethylammonium decatungstate ([(CH3)4N]4W10O32), and benzyltriethylammonium decatungstate ([(C2H5)3NC7H7]4W10O32), were synthesized and then used as a catalyst in the extractive catalytic oxidative desulfurization (ECODS) system in the ionic liquid (IL) of [Bmim]PF6, and hydrogen dioxide (H2O2) was used as an oxidant. During the optimized process, the sulfur level in the model oil (1000 ppm S) can be reduced to 8 ppm, which is consistent with the standards of deep desulfurization. The temperature, the reaction time, and the amount of H2O2 and catalyst, as well as the type of the cations of decatungstates, all played vital roles in desulfurization efficiency, which were studied in detail to optimize the reaction conditions. The system could be recycled five times before the sulfur removal decreased sharply.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900754f

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 9028–9033

Titre :	Development of an entrained flow gasifier model for process optimization study
Type de document :	texte imprimé
Auteurs :	Enrico Biagini, Auteur ; Alessio Bardi, Auteur ; Gabriele Pannocchia, Auteur
Année de publication :	2009
Article en page(s) :	pp. 9028–9033
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Gasifier model Coal gasification Hydrogen
Résumé :	Coal gasification is a versatile process to convert a solid fuel in syngas, which can be further converted and separated in hydrogen, which is a valuable and environmentally acceptable energy carrier. Different technologies (fixed beds, fluidized beds, entrained flow reactors) are used, operating under different conditions of temperature, pressure, and residence time. Process studies should be performed for defining the best plant configurations and operating conditions. Although “gasification models” can be found in the literature simulating equilibrium reactors, a more detailed approach is required for process analysis and optimization procedures. In this work, a gasifier model is developed by using AspenPlus as a tool to be implemented in a comprehensive process model for the production of hydrogen via coal gasification. It is developed as a multizonal model by interconnecting each step of gasification (preheating, devolatilization, combustion, gasification, quench) according to the reactor configuration, that is an entrained flow reactor. The model removes the hypothesis of equilibrium by introducing the kinetics of all steps and solves the heat balance by relating the gasification temperature to the operating conditions. The model allows to predict the syngas composition as well as quantify the heat recovery (for calculating the plant efficiency), “byproducts”, and residual char. Finally, in view of future works, the development of a “gasifier model” instead of a “gasification model” will allow different reactor configurations to be compared.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801804g

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 9023–9027

Titre :	Molecular diffusion coefficients of the multicomponent gas−crude oil systems under high temperature and pressure
Type de document :	texte imprimé
Auteurs :	Ping Guo, Auteur ; Zhouhua Wang, Auteur ; Pingping Shen, Auteur
Année de publication :	2009
Article en page(s) :	pp. 9023–9027
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Oil−gas system Molecular diffusion Mass transfer
Résumé :	The molecular diffusion of an oil−gas system is a key factor to determine the mass transfer rate. The actual mass transfer between oil and gas is an unsteady-state process. In this paper, the diffusion coefficients of the N2-rich gas−crude oil, CO2-rich gas−crude oil, and CH4-rich gas−crude oil systems were determined at 60 °C and 20 MPa by the mutual diffusion model developed. Results of the coefficient measurements show obvious transit characteristics of the gas−oil diffusion processes. Both the required equilibrium time and the diffusion rate depend on not only the diffusion gas but also the diffusion system. The diffusion gas concentration affects the diffusion coefficients slightly.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801671u

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 9013–9022

Titre :	Parametric study of the membrane process for carbon dioxide removal from natural gas
Type de document :	texte imprimé
Auteurs :	Dongxiao Yang, Auteur ; Zhi Wang, Auteur ; Jixiao Wang, Auteur
Année de publication :	2009
Article en page(s) :	pp. 9013–9022
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Cross-flow model Removing CO2Natural gas
Résumé :	In this work, the cross-flow model is compared with the cocurrent flow model and the countercurrent flow model for the process of removing CO2 from natural gas. According to the comparison result, the cross-flow model is used for the analysis of the process of CO2 removal from the natural gas. Analysis results indicate that the membrane area is not a monodrome function of the selectivity and both the effects of the fast gas (CO2) permeability and the slow gas (CH4) permeability on membrane area and CH4 recovery are studied. Similar analysis is carried out for the operating pressures. Both the single stage system and the two-stage system with a recycle are studied. In order to reduce the membrane area required, membranes with high permeability and selectivity less than 100 are preferable. With increasing feed side pressure and decreasing permeate side pressure, the membrane area required decreases and the CH4 recovery increases. For the single-stage system using a commercial membrane with selectivity of 20, the CH4 recovery is lower than 90% at a product purity of 98%. Only when the membrane with selectivity higher than 50 is used, the separation of CH4 recovery >98% and product purity >98% target can be fulfilled by the single stage system. Using the two-stage system with a membrane selectivity of 20, the separation target can be achieved. In the two-stage system, the permeate gas of the first stage has to be compressed before it can be sent to the next stage. The compression energy required between stages is estimated to be 107.5 KJ/m3(STP) of feed for the process discussed in this paper. Even considering the conversion factor between heat and electricity of 3−4, the energy consumption of a two-stage membrane system is still much less than that of the amine absorption process which is about 600−900 KJ/(m3(STP) of feed).
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900028m

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 9006–9012

Titre :	Selection of ionic liquids as entrainers for the separation of ethyl acetate and ethanol
Type de document :	texte imprimé
Auteurs :	Qunsheng Li, Auteur ; Jiguo Zhang, Auteur ; Zhigang Lei, Auteur
Année de publication :	2009
Article en page(s) :	pp. 9006–9012
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Ionic liquidsMolecular structures Vapor−liquid equilibrium
Résumé :	This work tries to explore the relation between molecular structures of ionic liquids (ILs) as entrainers and separation performance on ethyl acetate (1) and ethanol (2). The vapor−liquid equilibrium (VLE) data have been measured for ethyl acetate (1) + ethanol (2) containing ILs at 101.32 kPa. The ionic liquids investigated were 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]+[BF4]−) and 1-methyl-3-octylimidazolium tetrafluoroborate ([OMIM]+[BF4]−), as well as 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM]+[BF4]−) that has been studied in our previous work. All the ILs could give rise to the salting-out effect. It was found that, at low IL concentration, the separation ability of ILs is in the order [EMIM]+[BF4]− > [BMIM]+[BF4]− > [OMIM]+[BF4]−, while at high IL concentration (x3 = 0.10−0.30) the separation ability of ILs is in the order [OMIM]+[BF4]− > [EMIM]+[BF4]− > [BMIM]+[BF4]− due to the difference of polarity of the three ILs and demixing effect. [EMIM]+[triflate]− was included as entrainer and compared with the tetrafluoroborate-based ILs. The measured ternary data were correlated using the NRTL model.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8017127

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8999–9005

Titre :	Modeling and control of a proton exchange membrane fuel cell system with alternative fuel sources
Type de document :	texte imprimé
Auteurs :	Wei Wu, Auteur ; Che-Chuan Pai, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8999–9005
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Proton exchange membrane Methanol fuel Water flow Open-loop tests
Résumé :	The aim of this work is to study the control of the proton exchange membrane (PEM) fuel cell stack system with alternative methanol fuel. An external circulating water flow design not only plays the role of heat exchanger, but also it is the one of reactants of the methanol reforming system. The open-loop tests show that the variation of water flow causes unsteady hydrogen production at the exit of fuel processing units (FPUs) to seriously affect the stack temperature and reduce the performance of the power system. Since the reforming-integrated fuel cell system has strongly nonlinear behavior, the model-free fuzzy control technique is used to ensure the stable output regulation. On the basis of the proportional−integral−derivative (PID) configuration with one tuning parameter, the closed-loop simulation shows that the controller reliability is satisfactory when unknown inlet perturbations and loads appear.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801460t

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8985–8998

Titre :	Method for evaluation of thermochemical and hybrid water-splitting cycles
Type de document :	texte imprimé
Auteurs :	Miguel Bagajewicz, Auteur ; Thang Cao, Auteur ; Robbie Crosier, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8985–8998
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Thermochemical water-splitting cycles Hybrid water-splitting cycles Evaluation
Résumé :	This paper presents a methodology for the preliminary evaluation of thermochemical and hybrid water-splitting cycles based on efficiency. Because the method does not incorporate sufficient flowsheet details, the efficiencies are upper bounds of the real efficiencies. Nonetheless, they provide sufficient information to warrant comparison with existing well-studied cycles, supporting the decision to disregard them when the bound is too low or continuing their study. In addition, we add features not present in previous works: equilibrium conversions as well as excess reactants are considered. The degrees of freedom of each cycle (temperatures, pressures, and excess reactants) were also considered, and these values were varied to optimize the cycle efficiency. Ten cycles are used to illustrate the method.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801218b

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8980–8984

Titre :	Measuring and controlling model of pulp kappa number with spectroscopy during batch sulfite pulping process
Type de document :	texte imprimé
Auteurs :	Wenhao Shen, Auteur ; Xiaoquan Chen, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8980–8984
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Pulp kappa number Spectroscopy
Résumé :	Aiming at the difficulties and problems of online measurement of pulp kappa number during batch pulping, this paper proposes a new measuring idea, which is to predict the lignin content in pulp through the measurement of dissolved lignin in cooking liquor with spectral technology. The basic and modified mathematical model of kappa number during sulfite pulping as well as the end point controlling model are put forward in detail. The site running result shows that the introduction of modified factor ε, which represents the change of the total lignin amount added into the digester, is effective. Therefore, the online measurement of kappa number and the determination of the end point of pulping can be achieved.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900327a

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8966–8979

Titre :	Development of ARX Models for predictive control using fractional order and orthonormal basis filter parametrization
Type de document :	texte imprimé
Auteurs :	Muddu Madakyaru, Auteur ; Anuj Narang, Auteur ; Sachin C. Patwardhan, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8966–8979
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Model predictive control ARX models Fractional-order differential operators Orthonormal basis filters
Résumé :	Among various industrial vendors of model predictive control (MPC) schemes, ARX appears to be a popular choice of model structure while models for predictive control schemes are being developed. These models are, however, nonparsimonious in the number of model parameters. As a consequence, the length of the data required to keep the variance errors low while using the conventional ARX structure is significantly large. Thus, if it is possible to reparametrize the ARX model such that fewer parameters are required at the identification stage, then it is possible to reduce the length of identification data and thereby reduce the cost involved in model identification exercise. In this work, we explore the possibility of reparametrizing ARX models using the fractional-order differential operators (FO-ARX) and orthonormal basis filters (OBF-ARX). We also propose a novel approach for identification of time delay matrix from multivariate data using ARX and OBF-ARX models. The efficacy of the proposed modeling technique is demonstrated by conducting simulation studies on the benchmark Shell control problem. Analysis of the simulation results reveals that, when compared with the conventional high-order ARX structure, the FO-ARX and the OBF-ARX are better model parametrizations when the data length is less. In particular, OBF-ARX parametrization is able to estimate the time delay matrix from multivariate data quite accurately. The experimental studies establish the feasibility of using the proposed FO-ARX and OBF-ARX models for formulating MPC schemes.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8009439

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8961–8965

Titre :	Water vapor permeation resistance of polycarbonate at various temperatures
Type de document :	texte imprimé
Auteurs :	Sung In Moon, Auteur ; C. W. Extrand, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8961–8965
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Water vapor Polycarbonate Permeability coefficients Diffusion coefficients Solubility coefficients
Résumé :	The permeation rate of water vapor through polycarbonate (PC) was examined. Permeability (P), diffusion (D), and solubility (S) coefficients were measured at temperatures ranging from 25 to 80 °C. P values remained almost constant over this temperature range. On the other hand, D values increased and S values decreased exponentially with temperature. These data represent a broad map of the mass-transport characteristics of water through PC, which can be used to estimate break-though times, permeation rates, absorption, desorption/outgassing, and moisture content over a wide range of temperature and humidity.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900842t

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8954–8960

Titre :	Adsorption of Cu2+ on amino functionalized silica gel with different loading
Type de document :	texte imprimé
Auteurs :	Manu V., Auteur ; Haresh M. Mody, Auteur ; Hari C. Bajaj, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8954–8960
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Silica gel Amino functionalized silica gel Cu2+ Adsorption
Résumé :	Silica gel (G) and amino functionalized silica gel with three different loading of an aminopropyl group viz. 0.51, 1.01, and 1.45 mmol/g, (GN1, GN2, and GN3) were synthesized, characterized, and used as adsorbents for the adsorption of Cu2+ ions from aqueous solution. The specific surface area, pore volume, and BJH pore size of silica gel decreased with an increase in the loading of aminopropyl groups. Kinetic of adsorption of Cu2+ on GN2 followed pseudosecond order. Adsorption isotherms of Cu2+ on functionalized silica samples were best fit by the Sips model for all the three functionalized silica gels, among the four models used to describe the Cu2+ adsorption isotherms. The monolayer copper adsorption capacity for the gel GN1 (0.515 mmol Cu2+/g) and GN2 (0.55 mmol Cu2+/g) were found to be almost similar even when the loading of the amino group increased from 0.51 to 1.01 mmol/g. The NH2/Cu mole ratio was found to be around 1 and 2 for GN1 and GN2, respectively. In the case of GN3 (1.45 mmol NH2/g), the monolayer capacity was found to be 1.05 mmol Cu2+/g with a NH2/Cu mole ratio of 1.38. This study indicates that the population density of NH2 determines the NH2/Cu2+ ratio at saturation of Cu2+ on the functionalized silica gel and the affinity of the gel for the Cu2+.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900273v

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8950–8953

Titre :	Yield behavior of gelled waxy oil : effect of stress application in creep ranges
Type de document :	texte imprimé
Auteurs :	Kyeongseok Oh, Auteur ; Mark Jemmett, Auteur ; Milind Deo, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8950–8953
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Wax components Crude oilYield strength
Résumé :	Wax components in a crude oil start to precipitate when the surrounding temperature is lower than the wax appearance temperature. When wax gel develops under static conditions, a certain amount of pressure is needed to overcome the yield strength of the gelled oil in the pipeline for restart. It is shown that paraffinic components contribute to the evolving gel strength of the oil when cooled below the pour point. The gel strength was determined by the measurement of yield stress with and without subjecting the samples to creep stress. The existence of primary creep, secondary creep, and tertiary creep, was observed under isothermal conditions depending on the magnitude of the stress applied. This study explores the effect of prior creep stress with and without subsequent cooling of the samples. No significant degradation (reduction in yield stress) was observed after prior creep of the gelled oil at the same temperature. In the case of the subsequent cooling, applying prior creep stress application results in the dramatic increase of gel strength.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie9000597

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8944–8949

Titre :	Scaling the long-term shear stability of aqueous pigment dispersions
Type de document :	texte imprimé
Auteurs :	Evagelos K. Athanassiou, Auteur ; Hanspeter Gradischnig, Auteur ; Peter Siemsen, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8944–8949
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	ShearPigment dispersions
Résumé :	The industrial application of paints today involves the handling of millions of tons of pigment dispersions. Shear and mechanical stress during pumping, storage, or processing significantly affect color and shelf life. Currently, mainly empirical test series and pilot-scale process models are used to assess the stability of such dispersions and provide marginal guidance when developing or testing large-scale paint applications. Scaling the stability against shear stress is particularly important for water-based metal pigment dispersions where damage to the pigment flakes causes their deterioration. The present work investigates the scaling of shear stress from the production line (>1000 tons/yr) to laboratory scale (100-g scale). We analytically show why the integrated shear stress on a specific dispersion can be deconvoluted into a series of individual shear stress contributions. These individual contributions can be accurately reproduced in the laboratory using a Couette-type shearing setup similar to a classical rheometer. As a representative example, a stable and a shear-sensitive paint from an automotive production line was sampled over 4 months of production. The evolving deterioration, color changes, and dispersion instability could be accurately reproduced using the scaling method outlined here.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8017324

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8934–8943

Titre :	Examination of the low-temperature region in a downdraft gasifier for the pyrolysis product analysis of biomass air gasification
Type de document :	texte imprimé
Auteurs :	Weerawut Chaiwat, Auteur ; Isao Hasegawa, Auteur ; Kazuhiro Mae, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8934–8943
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Nitrogen Low-temperature region Gas-treated precursors
Résumé :	Treatment of biomass in nitrogen and air at 240−340 °C was conducted in order to examine the low-temperature region in a downdraft gasifier by analyzing the treated precursors and product distribution. Gas-treated precursors were then pyrolyzed in flash mode at 764 °C for further analysis. Overall, the tar yield decreased from approximately 50 wt % to less than 20 wt % upon oxidation of the sample at a very low heating rate to 260−300 °C in air. Moreover, tar evolution was almost completely suppressed during the subsequent flash pyrolysis. This indicates that the structure of the treated precursors was gradually changed to suppress tar release through cross-linking reactions and partial oxidation. From elemental analysis of the precursors treated with air, it was also estimated that dehydration and partial oxidation proceeded simultaneously. The results indicate that the release of tar products such as dimers can be partially suppressed by air treatment at low temperature.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900264n

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8926–8933

Titre :	Reaction-diffusion model for irregularly shaped ammonia synthesis catalyst and its verification under high pressure
Type de document :	texte imprimé
Auteurs :	Tao Li, Auteur ; Mao-sheng Xu, Auteur ; Bing-chen Zhu, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8926–8933
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Reaction−diffusion model Irregularly shaped ammonia synthesis catalyst Intrinsic kinetics equation
Résumé :	A one-dimensional isothermal multicomponent reaction−diffusion model was established for irregularly shaped ammonia synthesis catalyst A301. The intrinsic kinetics equation was derived from the experimental data obtained under high pressure ranging from 7.5 to 10.5 MPa. A feasible method was developed to measure the shape factor of the irregularly shaped ammonia synthesis catalyst. The dynamics single pellet string reactor method as well as parameter estimation was applied to get the tortuosity factor of irregularly shaped ammonia synthesis catalyst. The orthogonal collocation method combined with the Broyden method was employed to solve the model equations, and the internal-diffusion efficiency factor and the concentration distributions of individual components in the catalyst were obtained. The multicomponent reaction−diffusion model was verified by the global kinetics data obtained in a gradientless reactor. The calculation data agreed well with experimental data, so the model can be used to describe the processes of multicomponent reaction and diffusion in the irregularly shaped catalyst. The integrative methodology of catalyst engineering presented in this paper can be extended to guide catalyst preparation and reactor design.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie9001266

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8920–8925

Titre :	Effect of alkaline catalysts on hydrothermal conversion of glycerin into lactic acid
Type de document :	texte imprimé
Auteurs :	Zheng Shen, Auteur ; Fangming Jin, Auteur ; Yalei Zhang, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8920–8925
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Glycerin Hydrothermal treatment Alkaline catalysts Lactic acid
Résumé :	Hydrothermal treatment of glycerin was carried out at 300 °C by using eight alkaline catalysts, including hydroxides of alkali metals, alkaline-earth metals, and aluminum. All alkaline catalysts promoted the formation of lactic acid or lactate salts from glycerin, except for Al(OH)3. The alkali-metal hydroxides were more effective than alkaline-earth-metal hydroxides on the catalysis of hydrothermal reactions. On the hydrothermal conversion of glycerin into lactic acid, the catalytic effectiveness followed the sequence of KOH > NaOH > LiOH for alkali-metal hydroxides, and Ba(OH)2 > Sr(OH)2 > Ca(OH)2 > Mg(OH)2 for alkaline-earth hydroxides. An excellent lactic acid yield of 90% was attained on hydrothermal conversion of glycerin at 300 °C with KOH or NaOH as a catalyst. KOH was superior to NaOH as a catalyst since it worked at a lower concentration or within a shorter reaction time to obtain the same lactic acid yield. The hydrothermal conversion of glycerin depended not only on the hydroxide ion concentration but also on the metal ions of catalysts.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900937d

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8913–8919

Titre :	Corrosion behavior of carbon steel in the monoethanolamine−H2O−CO2−O2−SO2 system
Type de document :	texte imprimé
Auteurs :	Nattawan Kladkaew, Auteur ; Raphael Idem, Auteur ; Paitoon Tontiwachwuthikul, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8913–8919
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Carbon steel Corrosion Monoethanolamine−H2O−CO2−O2−SO2 system
Résumé :	The effects of operating parameters on the corrosion of carbon steel in the monoethanolamine (MEA)−H2O−CO2−O2−SO2 system were investigated using two different corrosion measurement techniques. The corrosion studies were conducted using a 273A potentiostat using MEA, O2, and SO2 concentrations and CO2 loading in the ranges of 1−7 kmol/m3, 0−100%, 0−204 ppm, and 0−0.5 mol CO2/mol MEA, respectively, at corrosion temperatures in the range of 303−353 K. The experimental results showed, for the first time, that a higher concentration of SO2 in a simulated flue gas stream induces a higher corrosion rate essentially because of the increase in the hydrogen ion concentration generated by reactions of SO2 and H2O as well as SO2, O2, and H2O. Also, an increase in oxygen concentration in the simulated flue gas stream causes a higher corrosion rate due to the increasing solubility of oxygen and, in turn, a higher amount of dissolved oxygen in the liquid phase. The results further show that an increase in the concentrations of MEA, O2, and SO2 as well as CO2 loading will cause the generation of higher amounts of hydrogen or hydronium ions, as well as carbonic acid and bicarbonate ions, and this is what leads to a higher corrosion rate.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie9007453

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8906–8912

Titre :	Long-term behavior of CaO-based pellets supported by calcium aluminate cements in a long series of CO2 capture cycles
Type de document :	texte imprimé
Auteurs :	Vasilije Manovic, Auteur ; Edward J. Anthony, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8906–8912
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	CaO-based pellets CO2 carrying capacity Thermogravimetric analyzer Scanning electron microscopy
Résumé :	A series of carbonation/calcination tests consisting of 1000 cycles was performed with CaO-based pellets prepared using hydrated lime and calcium aluminate cement. The change in CO2 carrying capacity of the sorbent was investigated in a thermogravimetric analyzer (TGA) apparatus and the morphology of residues after those cycles in the TGA was examined by scanning electron microscopy (SEM). Larger quantities of sorbent pellets underwent 300 carbonation/calcination cycles in a tube furnace (TF), and their properties were examined by nitrogen physisorption tests (BET and BJH). The crushing strength of the pellets before and after the CO2 cycles was determined by means of a custom-made strength testing apparatus. The results showed high CO2 carrying capacity in long series of cycles with an extremely high residual activity of the order of 28%. This superior performance is a result of favorable morphology due to the existence of large numbers of nanosized pores suitable for carbonation. This morphology is relatively stable during cycles due to the presence of mayenite (Ca12Al14O33) in the CaO structure. However, the crushing tests showed that pellets lost strength after 300 carbonation/calcination cycles, and this appears to be due to the cracks formed in the pellets. This effect was not observed in smaller particles suitable for use in fluidized bed (FBC) systems.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie9011529

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8890–8905

Titre :	Review of major design and scale-up considerations for solar photocatalytic reactors
Type de document :	texte imprimé
Auteurs :	Rowan J. Braham, Auteur ; Andrew T. Harris, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8890–8905
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Photocatalytic reactors Industrial-scale implementation
Résumé :	Photocatalytic processes are applicable in wastewater treatment, energy production, chemical synthesis, and greenhouse gas mitigation and thus have the potential to address both the consumption of nonrenewable fossil fuels and global warming, two of the greatest problems facing humankind. The ability to achieve these outcomes using only solar energy as an input is particularly attractive. However, the implementation of most photocatalytic processes at an effective scale requires the use of a photoreactor, a device which brings photons, a photocatalyst and reactants into contact, as well as collecting the reaction products. In this work, we review the state-of-the-art in solar photoreactor design and assess those systems which are most applicable for industrial-scale implementation. Designs for parabolic trough, compound parabolic, inclined plate, double skin sheet, rotating disk, water bell, fiber optic, and fixed/fluidized bed photoreactors are qualitatively discussed and compared. Compound parabolic photoreactors are most suited to near term applications at pilot-scale (>1000 L/day) due to their advantageous light collecting properties and well-known design methodology. Double-skin sheet photoreactors are also suited to near term applications; however, significantly less is known about their design and performance discrepancies between studies in the literature have been reported. Compared to other photoreactor designs, the significantly simplified design and low material cost of inclined plate photoreactors makes them particularly suitable for use in economically and logistically challenged areas where the volumes to be treated are small (<100 L/day). Fluidized bed photoreactors are highly efficient, but more research is needed into their design and operation for effective use with solar radiation. The other photoreactor designs reviewed are unlikely to see wide use due to, variously, high mechanical complexity, poor efficiency, and/or susceptibility to environmental conditions but may find limited use in specialized applications, e.g. in instances where it is advantageous to separate the light gathering and photocatalytic components of the photoreactor.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900859z

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8881–8889

Titre :	Novel parallel integration of microfluidic device network for emulsion formation
Type de document :	texte imprimé
Auteurs :	Georgios Tetradis-Meris, Auteur ; Damiano Rossetti, Auteur ; Concepción Pulido de Torres, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8881–8889
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Monodispersed emulsions Microfluidic platform Matlab
Résumé :	This work describes a design strategy to scale up microfluidics for producing monodispersed emulsions. Scale-up to 180 microfluidic devices with tight distribution of droplet size has been achieved (coefficient of variation CV ∼ 5%) by designing a system that is capable of operating easily without active control on single devices within the microfluidic platform. This has been achieved by using existing knowledge gained in the formation of monodispersed emulsions using a single device. We have identified three important factors affecting the scale-up of microfluidic systems that can benefit industrial scale-up processing. First, we used a network model simulation (Matlab) to evaluate two different branching layouts used to distribute liquids from a single manifold into the parallelized device network. We checked how fabrication tolerances could affect droplet formation, and as a result of this step, the ladder-type layout was preferred to the tree-type arrangement. The second important contribution of this work is the introduction of separate drainage manifolds for the two phases connecting all the input streams which have improved the performance and the operability of the system. Finally, we introduced a large opening after a short channel (150 μm) downstream of the junction where the droplet is formed. This opening acts like a reservoir to damp any pressure variation which could travel back to the inlet point and disturb the flow of neighboring devices.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900165b

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8872–8880

Titre :	Enhancing the throughput of membrane emulsification techniques to manufacture functional particles
Type de document :	texte imprimé
Auteurs :	Qingchun Yuan, Auteur ; Nita Aryanti, Auteur ; Gemma Gutiérrez, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8872–8880
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Membrane emulsification system Cross-flow Rotating membrane technology
Résumé :	Formulation technologies increasingly demand the manufacture of droplets with user-controlled size and size distributions for applications in emulsions, capsules, and semisolid particulates. These are used in various functional consumer products. This paper introduces methods to enhance throughput for two types of membrane emulsification system, using cross-flow and rotating membrane technology. Modification of the interaction between the dispersed phase and the surface of the membrane, the inner wall of the pores (through control of hydrophobicity), pore orientation, and pore shape is demonstrated to increase emulsion droplet productivity. Such methods can also be deployed in the production of capsule materials using emulsion precursors. The possible mechanisms underlying the enhancements are discussed. It is concluded that noncircular pores can offer significant process benefits for the production of uniform droplets and semisolid particulates. It is demonstrated that the droplet formation rate can be doubled through optimization of the orientation of noncircular pores in a rotating membrane process.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801929s

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8865–8871

Titre :	Thermal unfolding of a double-domain protein : molecular dynamics simulation of rhodanese
Type de document :	texte imprimé
Auteurs :	Ying Ren, Auteur ; Jian Gao, Auteur ; Wei Ge, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8865–8871
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Bovine liver rhodanese Explicit solvent molecular dynamics simulations
Résumé :	The thermal unfolding process of bovine liver rhodanese, composing two globular domains (N-domain and C-domain) with similar tertiary structures, has been studied by explicit solvent molecular dynamics (MD) simulations at high temperatures of 450 and 500 K, as well as 308 K for comparisons. The results are in good agreement with the available experimental results (Horowitz, P. M.; Butler, M. Interactive Intermediates Are Formed During the Urea Unfolding of Rhodanese. J. Biol. Chem. 1993, 268 (4), 2500−2504. Shibatani, T.; Kramer, G.; Hardesty, B.; Horowitz, P. M. Domain Separation Precedes Global Unfolding of Rhodanese. J. Biol. Chem. 1999, 274 (47), 33795−33799. Ybarra, J.; Bhattacharyya, A. M.; Panda, M.; Horowitz, P. M. Active Rhodanese Lacking Nonessential Sulfhydryl Groups Contains an Unstable C-Terminal Domain and Can Be Bound, Inactivated, and Reactivated by GroEL. J. Biol. Chem. 2003, 278 (3), 1693−1699). Besides that our simulation can also depict more dynamic details of the unfolding process. The solvent accessible surface area (SASA) shows a remarkable increase mainly due to a more exposed hydrophobic area, indicating that the hydrophobic interaction is considerably weaker at high temperatures. Comparisons between the thermal stabilities of equivalent secondary structures in both domains suggest that the C-domain is more fragile than the N-domain and the breaking down of the secondary structures follows the pattern [α-helix]→[bend, turn, 3-helix, and 5-helix]. Different regimes of unfolding intermediates have also been discussed.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801441x

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8856–8864

Titre :	Effect of surfactants on iridescence developed by swollen lamellar phase of C12-alkenylsuccinic acid
Type de document :	texte imprimé
Auteurs :	Sudipta G. Dastidar, Auteur ; Bharath P., Auteur ; Antara Pal, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8856–8864
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	C12-alkenylsuccinic acid Ionic surfactants Nonionic surfactant Cationic surfactantSmall angle X-ray scattering
Résumé :	The iridescence phenomenon of C12-alkenylsuccinic acid (ASA) is a result of the coherent reflection of light from periodically ordered alternating lamellar surfactant stacks and solvent molecules. Here we report the effect of cationic, anionic, and nonionic surfactants on the iridescence of ASA. It was observed that ionic surfactants resulted in destabilization of the iridescence of ASA, while the addition of nonionic surfactant stabilized the system. The nature of the interactions of these surfactants on ASA was investigated using reflectance spectroscopy, differential scanning calorimetry, optical microscopy, and small angle X-ray scattering (SAXS). The bilayer thickness was determined using reflectance spectra, SAXS, and theoretical calculations. It was observed that the nonionic surfactant does not alter the lamellar spacing of ASA, while ionic surfactant was seen to lower it by creating water-filled defects. The diffraction patterns also exhibit an additional broad peak which indicates formation of uncorrelated bilayers. This study thus provides understanding of such swollen lamellar systems.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie802011w

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8848–8855

Titre :	Generation of geometrically confined droplets using microchannel arrays : effects of channel and step structure
Type de document :	texte imprimé
Auteurs :	Isao Kobayashi, Auteur ; Marcos A. Neves, Auteur ; Tomoyuki Yokota, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8848–8855
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Geometrically confined droplets Microchannel arrays
Résumé :	The aim of this study was to investigate the generation characteristics of geometrically confined droplets using microchannel (MC) arrays made of single crystal silicon. Twelve MC array devices, each consisting of four MC arrays, were used in this study. Each MC array consists of rectangular MCs (5 μm in height) with or without a step. This study focused on the effects of the MC width and step height. Refined soybean oil was used as a dispersed phase, and a Milli-Q water solution containing 1.0 wt % sucrose monolaurate was used as a continuous phase. When rectangular MCs with a step height of 4.8 μm were used, geometrically confined droplets with a height of 9.8 μm were obtained, and their diameter and volume gradually increased with increasing MC width. In particular, highly uniform discoid droplets with coefficients of variation below 4% were obtained using the rectangular MCs with an appropriate width range. In contrast, droplets could not be generated from rectangular MCs without a step. When rectangular MCs with a width of 27.6 μm were used, the step height affected the resultant droplet shape. Highly uniform discoid droplets were generated via rectangular MCs with step heights below a critical value of ∼13 μm. Further increase in the step height resulted in the generation of highly uniform spherical droplets. The volume of the discoid droplets was somewhat larger than that of the spherical droplets.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8018998

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8842–8847

Titre :	Cloud point and microemulsion phase behavior of sodium linear alkylbenzene sulfonate with tetrabutyl- and benzyltributyl-substituted ammonium halides
Type de document :	texte imprimé
Auteurs :	Deeleep K. Rout, Auteur ; Siddharth Chauhan, Auteur ; Ashwani Agarwal, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8842–8847
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Cloud point phenomenon Binary water−anionic surfactant Organic salts
Résumé :	We report cloud point phenomenon in binary water−anionic surfactant (sodium linear alkylbenzene sulfonate, NaLAS) after incorporation of organic salts, such as tetrabutyl- and benzyltributyl- ammonium halides. The effect of alkyl/aromatic hydrophobic substituents of such reagents on the cloud point phenomenon was also investigated. It was observed that the aqueous solution clouding behavior is dependent upon surfactant concentration, type of hydrophobic substituent of the salt, and operating temperature. At a given temperature, with increasing surfactant concentration, a higher amount of salt is required for the onset of clouding. Besides, at a given surfactant concentration, the amount of salt required for the cloud point is inversely proportional to the temperature. With addition of an oil phase to the binary water(salt)−surfactant system, a three-phase microemulsion could be generated. Phase diagrams for these ternary systems were determined, and the formation of the microemulsion phase behavior was established from phase visualization and oil−water interfacial tension measurements.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801873f

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8837–8841

Titre :	Viscous fingering patterns and evolution of their fractal dimension
Type de document :	texte imprimé
Auteurs :	Suparna Sinha, Auteur ; Sujata Tarafdar, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8837–8841
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Viscous fingering patterns Newtonian defending fluid Castor oil Olive oil
Résumé :	We present a study of viscous fingering patterns which arise because of the instability at the interface of two fluids of dissimilar viscosities. Viscous fingering experiments were performed in a lifting Hele-Shaw cell with a Newtonian defending fluid, castor oil or olive oil, while the invading fluid is air. We focus here on the fractal dimension of the patterns and how it varies with the lifting pressure in the Hele-Shaw cell. The fractal dimension of the fluid−air interface is measured by the divider step method. It is seen that the dimension changes from a value close to one, indicating no instability, to a value around 1.6 as the pressure is increased. A change in fractal dimension with time is also observed as the pattern evolves. Measurement of the fractal dimension offers a method for quantifying the instability.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801836r

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8829–8836

Titre :	Effect of pore size on the growth of hydroxyapatite from mesoporous CaO-SiO2 substrate
Type de document :	texte imprimé
Auteurs :	Yan Deng, Auteur ; Xiaoke Li, Auteur ; Qiang Li, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8829–8836
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Mineral hydroxypapatite CaO−SiO2 bioactive material
Résumé :	In this work, a new approach for controlling the formation rate of hard tissue mineral hydroxypapatite (HAP) through the control of inner pore sizes of CaO−SiO2 bioactive material is proposed. Highly ordered mesoporous CaO−SiO2 (MCS) bioactive material with different pore sizes were synthesized through two types of surfactants, cetyltrimethyl-ammonium bromide (CTAB) and triblock copolymer EO106PO70EO106 (Pluronic F127). These two surfactants were selected for their different pore size formation tendencies, about 2.7 nm for CTAB template and 4.9 nm for F127 template. These two types of MCS materials have identical chemical composition but differ only in their pore sizes. Their bioactivities were evaluated by the incubation of the MCS in phosphate buffer solution at 37 °C for different periods of time. SEM showed that incubated MCS with 2.7-nm pore size could rapidly form a dense layer of HAP crystallites on its surfaces within a few hours, while incubated MCS with 4.9-nm pore size just formed a sparse layer of HAP after one week of incubation, with XRD to further confirm the HAP phase. This unique phenomenon was explained from theoretical calculations in which the critical nucleation diameter, 2r* of the HAP on the MCS substrate is above 2.7 nm but below 4.9 nm. HRTEM observation proved that HAP nuclei indeed formed inside the pores of the F127 templated MCS sample with 4.9-nm pore size, which could block inner pore channels and obstruct the transportation of dissolved Ca ion to the outer surface, and then hindered the subsequent surface HAP formation. However, no HAP nuclei were found in the pores of the CTAB-templated MCS sample with 2.7-nm pore size, due to the thermodynamic instability of HAP nuclei below their critical size, r, for which the unblocked pore channels facilitate the quick transportation of Ca ions and result in a much higher surface HAP growth rate. This finding provides a new material design strategy to accelerate the HAP formation rate simply by tuning its inner pore sizes below 2r of HAP, without the need for modification of the material’s chemical composition.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801796y

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8819–8828

Titre :	Preparation of uniformly sized chitosan nanospheres by a premix membrane emulsification technique
Type de document :	texte imprimé
Auteurs :	Pi-Ping Lv, Auteur ; Wei Wei, Auteur ; Fang-Ling Gong, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8819–8828
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Chitosan nanospheres Premix membrane emulsification technique
Résumé :	Chitosan nanospheres have great potential in drug controlled release systems, because they show excellent degradability, biocompatibility, and nontoxicity. The particle size control and size distribution of nanospheres are necessary in order to improve reproducibility, bioavailability, and repeatable release behavior. In order to prepare uniformly sized and size-controllable chitosan nanospheres, in this study, a premix membrane emulsification technique was developed on the basis of direct membrane emulsification, and the uniformly sized chitosan naonospheres were successfully prepared by optimizing preparation conditions. The detail preparation process is as follows: The chitosan aqueous solution was used as a dispersed phase, and the mixture of liquid paraffin and petroleum ether containing emulsifier was used as a continuous phase. The coarse emulsions were first prepared by low-speed stator homogenization and then poured into the premix reservoir. Nanodroplets were achieved by extruding the coarse emulsions through the SPG (Shirasu porous glass) membrane with a high pressure. The nanodroplets were further cross-linked to obtain chitosan nanospheres. In this process, several factors played key roles in obtaining chitosan nanoparticles with narrow size distribution, including the amounts of emulsifier in oil phase, the composition of oil phase, the concentration of chitosan, the ratio of water to oil phase, the transmembrane pressure and number of passes, and so on. The results showed that the chitosan nanospheres from 300 nm to 1.85 μm were successfully prepared by premix membrane emulsification by changing the pore size of the membrane and the polydispersity index could be as low as 0.027 under optimized conditions, and it is a potential technique to prepare size-controllable uniform chitosan nanospheres with fast production.
En ligne :	pubs.acs.org/doi/abs/10.1021/ie801758e

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8812–8818

Titre :	Solvent vapor-assisted imprinting of polymer films coated on curved surfaces with flexible PVA stamps
Type de document :	texte imprimé
Auteurs :	Rabibrata Mukherjee, Auteur ; Ganesh K. Patil, Auteur ; Ashutosh Sharma, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8812–8818
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Nonplanar surfaces Curved surfacesPolymer films Patterned polyvinyl alcohol stamp
Résumé :	We report a simple yet robust and reproducible technique to create surface patterns with submicrometer scale resolution on polymer films coated on nonplanar and curved surfaces at room temperature, without applying any external pressure. The imprinting is achieved by using a flexible, patterned polyvinyl alcohol (PVA) stamp in a controlled solvent vapor atmosphere, where the patterned foil comes in adhesive contact with a swollen and softened polymer film. The stamp bends along the contours of the curved surface to make a complete contact with a soft and swollen viscoelastic polymer film to make an imprint. The soft surface of the film then deforms on the length scale of each structure on the stamp to make a conformal contact, forming a negative replica of the stamp pattern on the film surface. The flexible PVA stamp is later dissolved in water after the patterning process is complete. It is shown that the technique is portable across a variety of polymer coatings, substrates, and geometries. Further, we also show that the same technique can be employed to create complex 2-D microstructures on nonplanar surfaces by multiple imprintings.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801740y

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8805–8811

Titre :	Rheological modeling of spherical polymeric gels and dispersions incorporating the influence of particle size distribution and surface forces
Type de document :	texte imprimé
Auteurs :	Girish Muralidharan, Auteur ; Venkataramana Runkana, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8805–8811
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Spherical polymeric gels Rheological modeling Dispersions Krieger−Dougherty equation
Résumé :	Polymer gels are cross-linked polymer particles that are finding applications in coatings, controlled drug delivery, consumer products, etc. A simple model for predicting the viscosity of spherical polymeric gels and dispersions which can help in the formulation of dispersions in terms of solids content, particle size distribution (PSD), pH, ionic strength, etc. is developed. The model is based on an extended Krieger−Dougherty (K−D) equation, which incorporates the influences of both PSD and interparticle surface forces. The two important parameters in the model are the maximum packing fraction and the interaction energy between the particles. Unlike previous models which treated them as adjustable parameters, they are computed as functions of particle, solvent, and suspension characteristics. The maximum packing fraction is calculated as a function of PSD using linear packing theory while the interaction energy is computed using well-established surface force theories. The hydrodynamic thickness of the polymer layer and the mean distance between the chain attachment points on the hard core particle surface are treated as adjustable parameters. The model predictions are in close agreement with the experimentally observed viscosity values for microgel and latex suspensions reported in the literature. The effect of PSD on the suspension viscosity was found to be more pronounced at high particle volume fractions than at low volume fractions.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801736q

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8789–8804

Titre :	Modeling of convection and macrosegregation through appropriate consideration of multiphase/multiscale phenomena during alloy solidification
Type de document :	texte imprimé
Auteurs :	R. Pardeshi, Auteur ; P. Dutta, Auteur ; A. K. Singh, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8789–8804
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Solidification processes Multiphase transport phenomena Physicochemical phenomena
Résumé :	Solidification processes are complex in nature, involving multiple phases and several length scales. The properties of solidified products are dictated by the microstructure, the macrostructure, and various defects present in the casting. These, in turn, are governed by the multiphase transport phenomena occurring at different length scales. In order to control and improve the quality of cast products, it is important to have a thorough understanding of various physical and physicochemical phenomena occurring at various length scales, preferably through predictive models and controlled experiments. In this context, the modeling of transport phenomena during alloy solidification has evolved over the last few decades due to the complex multiscale nature of the problem. Despite this, a model accounting for all the important length scales directly is computationally prohibitive. Thus, in the past, single-phase continuum models have often been employed with respect to a single length scale to model solidification processing. However, continuous development in understanding the physics of solidification at various length scales on one hand and the phenomenal growth of computational power on the other have allowed researchers to use increasingly complex multiphase/multiscale models in recent times. These models have allowed greater understanding of the coupled micro/macro nature of the process and have made it possible to predict solute segregation and microstructure evolution at different length scales. In this paper, a brief overview of the current status of modeling of convection and macrosegregation in alloy solidification processing is presented.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900164f

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8769–8788

Titre :	Milking diatoms for sustainable energy : biochemical engineering versus gasoline-secreting diatom solar panels
Type de document :	texte imprimé
Auteurs :	T. V. Ramachandra, Auteur ; Durga Madhab Mahapatra, Auteur ; Karthick, B, Auteur
Année de publication :	2009
Article en page(s) :	pp. 8769–8788
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Renewable energy Diatoms Solar panel
Résumé :	In the face of increasing CO2 emissions from conventional energy (gasoline), and the anticipated scarcity of crude oil, a worldwide effort is underway for cost-effective renewable alternative energy sources. Here, we review a simple line of reasoning: (a) geologists claim that much crude oil comes from diatoms; (b) diatoms do indeed make oil; (c) agriculturists claim that diatoms could make 10−200 times as much oil per hectare as oil seeds; and (d) therefore, sustainable energy could be made from diatoms. In this communication, we propose ways of harvesting oil from diatoms, using biochemical engineering and also a new solar panel approach that utilizes genomically modifiable aspects of diatom biology, offering the prospect of “milking” diatoms for sustainable energy by altering them to actively secrete oil products. Secretion by and milking of diatoms may provide a way around the puzzle of how to make algae that both grow quickly and have a very high oil content.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900044j

Industrial & engineering chemistry research / Paul, Donald R. . Vol. 48 N° 19

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