Jiupeng Du, Nelson Ibaseta, Pierrette Guichardon. Characterization of polyurea microcapsules synthesized with an isocyanate of low toxicity and eco-friendly esters via microfluidics: Shape, shell thickness, morphology and encapsulation efficiency. Chemical Engineering Research and Design, 2022, 182, pp.256-272. ⟨10.1016/j.cherd.2022.03.026⟩. ⟨hal-04063865⟩ Plus de détails...
There are some studies on the synthesis of polyurea microcapsules. However, there is hardly a case where both green solvents and non-toxic isocyanates are used, especially in microfluidics. In this work, an environmentally friendly chemical system of interfacial polymerization (isocyanate: HDB-LV; solvent: octyl salicylate or dibutyl adipate) is tested for the first time to produce polyurea microcapsules. The size of microcapsules is calibrated at 78 μm by microfluidics to quantitatively analyze the relationships among shell thickness, encapsulation efficiency and isocyanate concentrations. The influences of solvent types and reactant concentrations on the shape, morphology and shell thickness of microcapsules are studied. Esters with low water miscibility and low amine concentrations (lower reaction rate) are crucial for the formation of spherical microcapsules. An ester with high water miscibility can diffuse into the continuous phase during encapsulation, which results in broken microcapsules. A high concentration of amine can probably cause cross-linking not only at the interface but also inside the droplet template, which leads to microcapsule deformation. A linear relationship is observed between the shell thickness of microcapsules and the isocyanate concentration. Overall, a high encapsulation efficiency (more than 90%) for octyl salicylate is achieved with polyurea microcapsules.
Jiupeng Du, Nelson Ibaseta, Pierrette Guichardon. Characterization of polyurea microcapsules synthesized with an isocyanate of low toxicity and eco-friendly esters via microfluidics: Shape, shell thickness, morphology and encapsulation efficiency. Chemical Engineering Research and Design, 2022, 182, pp.256-272. ⟨10.1016/j.cherd.2022.03.026⟩. ⟨hal-04063865⟩
Pierrette Guichardon, Carlos Baqueiro, Nelson Ibaseta. Villermaux–Dushman Test of Micromixing Characterization Revisited: Kinetic Effects of Acid Choice and Ionic Strength. Industrial and engineering chemistry research, 2021, 60 (50), pp.18268-18282. ⟨10.1021/acs.iecr.1c03208⟩. ⟨hal-03514628⟩ Plus de détails...
The well-known Villermaux-Dushman system is nowadays widely used for examining the micromixing efficiency either in batch or continuous intensified reactors. However, a bibliographic review shows that kinetic data are too scattered for a reliable determination of the micromixing times. The Dushman reaction kinetics is then reexamined with the use of sulfuric and perchloric acids. The results confirm the fifth-order rate law. More precisely, the I-, H+, and IO3- dependence orders on the rate law are, respectively, 2, 2, and 1, under any condition. To be more consistent with the reactant concentrations used in the Villermaux-Dushman test, we extend their studied range, namely, 1.6 x 10(-3) M <= [I-](0) <= 1.6 x 10(-2) M, 1.2 x 10(-4) M <= [H+](0) <= 1.57 x 10(-2) M, and 4 x 10(-5) M <= [IO3-] <= 2.1 X 10(-4) M. The ionic strength varies up to 2 M. The experimental results show that the rate constant is still ionic-strength-dependent. The results obtained with sulfuric and perchloric acids are found to be consistent and in relatively good agreement at small ionic strengths (mu < 0.1 M) only. At a higher ionic strength, the use of sulfuric acid requires sustained attention to the constant of the second dissociation equilibrium. The nonideal solution behavior raising at a high ionic strength makes its estimation deeply sensitive.
Pierrette Guichardon, Carlos Baqueiro, Nelson Ibaseta. Villermaux–Dushman Test of Micromixing Characterization Revisited: Kinetic Effects of Acid Choice and Ionic Strength. Industrial and engineering chemistry research, 2021, 60 (50), pp.18268-18282. ⟨10.1021/acs.iecr.1c03208⟩. ⟨hal-03514628⟩
Journal: Industrial and engineering chemistry research
Pierrette Guichardon, Carlos Baqueiro, Nelson Ibaseta. Villermaux–Dushman Test of Micromixing Characterization Revisited: Kinetic Effects of Acid Choice and Ionic Strength. Industrial and engineering chemistry research, 2021, 60 (50), pp.18268-18282. ⟨10.1021/acs.iecr.1c03208⟩. ⟨hal-03597451⟩ Plus de détails...
The well-known Villermaux-Dushman system is nowadays widely used for examining the micromixing efficiency either in batch or continuous intensified reactors. However, a bibliographic review shows that kinetic data are too scattered for a reliable determination of the micromixing times. The Dushman reaction kinetics is then reexamined with the use of sulfuric and perchloric acids. The results confirm the fifth-order rate law. More precisely, the I-, H+, and IO3- dependence orders on the rate law are, respectively, 2, 2, and 1, under any condition. To be more consistent with the reactant concentrations used in the Villermaux-Dushman test, we extend their studied range, namely, 1.6 x 10(-3) M <= [I-](0) <= 1.6 x 10(-2) M, 1.2 x 10(-4) M <= [H+](0) <= 1.57 x 10(-2) M, and 4 x 10(-5) M <= [IO3-] <= 2.1 X 10(-4) M. The ionic strength varies up to 2 M. The experimental results show that the rate constant is still ionic-strength-dependent. The results obtained with sulfuric and perchloric acids are found to be consistent and in relatively good agreement at small ionic strengths (mu < 0.1 M) only. At a higher ionic strength, the use of sulfuric acid requires sustained attention to the constant of the second dissociation equilibrium. The nonideal solution behavior raising at a high ionic strength makes its estimation deeply sensitive.
Pierrette Guichardon, Carlos Baqueiro, Nelson Ibaseta. Villermaux–Dushman Test of Micromixing Characterization Revisited: Kinetic Effects of Acid Choice and Ionic Strength. Industrial and engineering chemistry research, 2021, 60 (50), pp.18268-18282. ⟨10.1021/acs.iecr.1c03208⟩. ⟨hal-03597451⟩
Journal: Industrial and engineering chemistry research
Jiupeng Du, Nelson Ibaseta, Pierrette Guichardon. Generation of an O/W emulsion in a flow-focusing microchip: importance of wetting conditions and of dynamic interfacial tension. Chemical Engineering Research and Design, 2020, ⟨10.1016/j.cherd.2020.04.012⟩. ⟨hal-02799613⟩ Plus de détails...
6 To date, there is no information on the microfluidic emulsification of dibutyl adipate and 7 n-butyl acetate in water. Since these solvents are very suitable for microencapsulation by 8 interfacial polymerization, it is highly necessary to study the emulsification behavior of these 9 solvents in microchannel. This work shows that the microfluidic emulsification of these sol-10 vents in water may fail to obtain stabilized flow regimes. This is due to droplet coalescence 11 and wall wetting, even if a hydrophilic microchip is used. Hydrodynamic results show that 12 squeezing and dripping regimes are especially affected because of the wall wetting by the 13 dispersed phase. This difficulty can be circumvented by adding a surfactant (here Tween 14 80) into the aqueous phase. However, high surfactant concentrations (ten times the crit-15 ical micelle concentration) should be used for the water-dibutyl adipate system. Indeed, 16 comparison of flow maps for several surfactant concentrations seems to indicate that the 17 dynamic interfacial tension is higher than the one expected (equilibrium), for surfactant 18 concentrations lower than one hundred times the critical micelle concentration. The esti-19 mated diffusion time of Tween 80 is compared to the droplet formation time at different 20 conditions. The choice of more appropriate dimensionless numbers to represent flow maps 21 is also discussed. 22
Jiupeng Du, Nelson Ibaseta, Pierrette Guichardon. Generation of an O/W emulsion in a flow-focusing microchip: importance of wetting conditions and of dynamic interfacial tension. Chemical Engineering Research and Design, 2020, ⟨10.1016/j.cherd.2020.04.012⟩. ⟨hal-02799613⟩
Pierre Haldenwang, Braulio Bernales, Pierrette Guichardon, Nelson Ibaseta. Simple Theoretical Results on Reversible Fouling in Cross-Flow Membrane Filtration. Membranes, 2019, Application of Membrane Filtration in Industrial Processes, and in the Treatment of Water and Industrial Wastewater), 9 (4), pp.48. ⟨10.3390/membranes9040048⟩. ⟨hal-02109009⟩ Plus de détails...
In cross-flow membrane filtration, fouling results from material deposit which clogs the membrane inner surface. This hinders filtration, which experiences the so-called limiting flux. Among the models proposed by the literature, we retain a simple one: a steady-state reversible fouling is modelled with the use of a single additional parameter, i.e., N d , the ratio of the critical concentration for deposition to the feed concentration at inlet. To focus on fouling, viscous pressure drop and osmotic (counter-)pressure have been chosen low. It results in a minimal model of fouling. Solved thoroughly with the numerical means appropriate to enforce the nonlinear coupling between permeation and concentration polarization, the model delivers novel information. It first shows that permeation is utterly governed by solute transfer, the relevant non-dimensional quantities being hence limited to N d and Pe in , the transverse Péclet number. Furthermore, when the role played by N d and moderate Pe in (say Pe in < 40) is investigated, all results can be interpreted with the use of a single non-dimensional parameter, F l , the so-called fouling number, which simply reads F l ≡ Pe in N −1 d. Now rendered possible, the overall fit of the numerical data allows us to put forward analytical final expressions, which involve all the physical parameters and allow us to retrieve the experimental trends.
Pierre Haldenwang, Braulio Bernales, Pierrette Guichardon, Nelson Ibaseta. Simple Theoretical Results on Reversible Fouling in Cross-Flow Membrane Filtration. Membranes, 2019, Application of Membrane Filtration in Industrial Processes, and in the Treatment of Water and Industrial Wastewater), 9 (4), pp.48. ⟨10.3390/membranes9040048⟩. ⟨hal-02109009⟩
Carlos Baqueiro, Nelson Ibaseta, Pierrette Guichardon, Laurent Falk. Influence of reagents choice (buffer, acid and inert salt) on triiodide production in the Villermaux–Dushman method applied to a stirred vessel. Chemical Engineering Research and Design, 2018, 136, pp.25-31. ⟨10.1016/j.cherd.2018.04.017⟩. ⟨hal-01771934⟩ Plus de détails...
This work studies how deeply the reagents choice influences micromixing characterisation by the Villermaux-Dushman method, when applying it to a 1 litre stainless steel standard vessel with two baffles, stirred by an inclined blade turbine. For the first time, borate and phosphate buffer are compared on their use in the method. It is observed that triiodide production is higher when borate buffer is used. Moreover, perchloric acid leads to higher triiodide production than sulphuric acid, when injecting the same concentration of both acids. Finally, the influence of the ionic strength is also studied, since there has been a great deal of controversy about it over the last years. The results show that the ionic strength affects triiodide production, although relatively slightly. Advice concerning the choice of the reagents is given in conclusion.
Carlos Baqueiro, Nelson Ibaseta, Pierrette Guichardon, Laurent Falk. Influence of reagents choice (buffer, acid and inert salt) on triiodide production in the Villermaux–Dushman method applied to a stirred vessel. Chemical Engineering Research and Design, 2018, 136, pp.25-31. ⟨10.1016/j.cherd.2018.04.017⟩. ⟨hal-01771934⟩
Gustavo Lopes, Nelson Ibaseta, Pierrette Guichardon, Pierre Haldenwang. Effects of solute permeability on permeation and solute rejection in membrane filtration. Chemical Engineering and Technology, 2018, 41 (4), pp.788-797. ⟨10.1002/ceat.201700203⟩. ⟨hal-01681108⟩ Plus de détails...
Membrane solute permeability plays a role in the buildup of concentration polarization in pressure-driven crossflow filtration processes, and thus in the determination of the permeate flux, solute rejection, retentate flux and concentration. We numerically examine reverse-osmosis desalination with membranes of fixed solvent permeability, but of variable selectivity with respect to the solute. The study highlights an intricate coupling between retentate and filtrate properties. In particular, it reveals that, for given values of solute permeability and feed concentration, there is a maximum operating pressure that optimizes solute rejection regardless of the feed salinity. The conditions leading to this and to other peculiar behaviors for permeation fluxes and concentrations are identified.
Gustavo Lopes, Nelson Ibaseta, Pierrette Guichardon, Pierre Haldenwang. Effects of solute permeability on permeation and solute rejection in membrane filtration. Chemical Engineering and Technology, 2018, 41 (4), pp.788-797. ⟨10.1002/ceat.201700203⟩. ⟨hal-01681108⟩
B. Bernales, Pierre Haldenwang, Pierrette Guichardon, Nelson Ibaseta. Prandtl model for concentration polarization and osmotic counter-effects in a 2-D membrane channel. Desalination, 2017, 404, pp.341 - 359. ⟨10.1016/j.desal.2016.09.026⟩. ⟨hal-01405589⟩ Plus de détails...
An accurate 2-D numerical model that accounts for concentration polarization and osmotic effects is developed for the cross-flow filtration in a membrane channel. Focused on the coupling between laminar hydrodynam-ics and mass transfer, the numerical approach solves the solute conservation equation together with the steady Navier-Stokes equations under the Prandtl approximation, which offers a simplified framework to enforce the non-linear coupling between filtration and concentration polarization at the membrane surface. The present approach is first validated thanks to the comparison with classical exact analytical solutions for hydrodynamics and/or mass transfer, as well as with approximated analytical solutions that attempted at coupling the various phenomena. The effects of the main parameters in cross-flow reverse osmosis (RO) or nanofiltration (NF) (feed concentration, axial flow rate, operating pressure and membrane permeability) on streamlines, velocity profile, longitudinal pressure drop, local permeate flux and solute concentration profile are predicted with the present numerical model, and discussed. With the use of data reported from NF and RO experiments, the Prandtl approximation model is shown to accurately correlate both average permeate flux and local solute concentration over a wide range of operating conditions.
B. Bernales, Pierre Haldenwang, Pierrette Guichardon, Nelson Ibaseta. Prandtl model for concentration polarization and osmotic counter-effects in a 2-D membrane channel. Desalination, 2017, 404, pp.341 - 359. ⟨10.1016/j.desal.2016.09.026⟩. ⟨hal-01405589⟩
Gustavo H. Lopes, Nelson Ibaseta, Pierrette Guichardon. How can osmosis and solute diffusion be coupled for the simultaneous measurement of the solvent and solute permeabilities of membranes?. Desalination, 2016, 387 (1), pp.61-74. ⟨10.1016/j.desal.2016.03.006⟩. ⟨hal-01290973⟩ Plus de détails...
A novel experimental method and its associated model are proposed for the simultaneous determination of membrane solute and solvent permeabilities, which are essential transport parameters of reverse osmosis models used for process simulation. The method utilizes a single bench-scale batch apparatus consisting of two stirred half-cells containing solutions of different concentrations separated by a membrane across which coupled non-steady-state solute diffusion and solvent osmosis take place countercurrently in the absence of transmembrane pressure difference. Results are presented from days-long determinations of the water and sodium chloride permeabilities of Filmtec BW30 and NF270 membrane samples for initial transmembrane salt concentration differences ranging from 1 g L-1 to 35 g L-1. When used as input parameters for the simulation of pilot reverse osmosis desalination tests, the osmotic-diffusive salt permeabilities approximated the experimental rejection rates.
Gustavo H. Lopes, Nelson Ibaseta, Pierrette Guichardon. How can osmosis and solute diffusion be coupled for the simultaneous measurement of the solvent and solute permeabilities of membranes?. Desalination, 2016, 387 (1), pp.61-74. ⟨10.1016/j.desal.2016.03.006⟩. ⟨hal-01290973⟩
Gustavo Henndel . Lopes, Nelson Ibaseta, Pierrette Guichardon, Pierre Haldenwang. Predicting Permeate Fluxes and Rejection Rates in Reverse Osmosis and Tight-Nanofiltration Processes. Chemical Engineering and Technology, 2015, 38 (4), pp.585-594. ⟨10.1002/ceat.201400654⟩. ⟨hal-01135689⟩ Plus de détails...
The performance of reverse osmosis and tight nanofiltration with flat-sheet membranes can be predicted accurately. The proposed numerical model solves the local momentum and mass conservation equations in the module's feed channel with solution-diffusion boundary conditions. Both qualitative and quantitative predictions of the permeate flux and of the rejection rate are obtained with an accuracy depending on the limitations of the solution-diffusion model for describing membrane mass transport and on the value of solute permeability. As an extension of the applications to plate-and-frame modules, the ability to describe the performance of processes carried out with spiral-wound modules is also tested with own desalination experiments and with data from the literature.
Gustavo Henndel . Lopes, Nelson Ibaseta, Pierrette Guichardon, Pierre Haldenwang. Predicting Permeate Fluxes and Rejection Rates in Reverse Osmosis and Tight-Nanofiltration Processes. Chemical Engineering and Technology, 2015, 38 (4), pp.585-594. ⟨10.1002/ceat.201400654⟩. ⟨hal-01135689⟩
Gustavo Henndel Lopes, Pierrette Guichardon, Nelson Ibaseta, Pierre Haldenwang. L’eau, ressource rare ? Gros plan sur le procédé de dessalement par membranes d’osmose inverse. L'Actualité Chimique, 2014, N° thématique: La chimie et la ville de demain Colloque Recherche de la Fédération Gay-Lussac, Paris, 4-6 décembre 2013, 390, pp.85-87. ⟨hal-01116186⟩ Plus de détails...
Le procédé d’osmose inverse s’impose aujourd'hui dans la production d’eau douce par dessalement. Des avancées en matière de prédiction des performances de ce procédé s’avèrent précieuses dans l’optimisation rapide et peu coûteuse des conditions de fonctionnement. L’interaction entre les propriétés de la membrane et les phénomènes prépondérants (polarisation de concentration, pression osmotique...) constitue un problème scientifiquement complexe, traité dans cette étude via une approche modélisation numérique-simulation-expérimentation, une question centrale pour le génie des procédés.
Gustavo Henndel Lopes, Pierrette Guichardon, Nelson Ibaseta, Pierre Haldenwang. L’eau, ressource rare ? Gros plan sur le procédé de dessalement par membranes d’osmose inverse. L'Actualité Chimique, 2014, N° thématique: La chimie et la ville de demain Colloque Recherche de la Fédération Gay-Lussac, Paris, 4-6 décembre 2013, 390, pp.85-87. ⟨hal-01116186⟩
G.H. Lopes, B. Bernales Chavez, Nelson Ibaseta, Pierrette Guichardon, Pierre Haldenwang. Prediction of Permeate Flux and Rejection Rate in RO and NF Membrane Processes: Numerical Modelling of Hydrodynamics and Mass Transfer Coupling. Procedia Engineering, 2012, 44, pp.1934-1936. ⟨10.1016/j.proeng.2012.09.001⟩. ⟨hal-01299944⟩ Plus de détails...
G.H. Lopes, B. Bernales Chavez, Nelson Ibaseta, Pierrette Guichardon, Pierre Haldenwang. Prediction of Permeate Flux and Rejection Rate in RO and NF Membrane Processes: Numerical Modelling of Hydrodynamics and Mass Transfer Coupling. Procedia Engineering, 2012, 44, pp.1934-1936. ⟨10.1016/j.proeng.2012.09.001⟩. ⟨hal-01299944⟩
Pierre Haldenwang, Pierrette Guichardon, Guillaume Chiavassa, N. Ibaseta. Exact solution to mass transfer in Berman flow: application to concentration polarization combined with osmosis in crossflow membrane filtration. International Journal of Heat and Mass Transfer, 2010, 53 (19-20), pp.3898-3904. ⟨10.1016/j.ijheatmasstransfer.2010.05.008⟩. ⟨hal-00907275⟩ Plus de détails...
Concentration polarization affects numerous systems of membrane separation, and combined with osmosis, it can cause substantial reductions in permeation. We establish an exact solution to the conservation law of a solute advected by Berman flow. This flow is characteristic of reverse osmosis or nanofiltration. The resulting concentration polarization is then combined with the osmosis (counter-) effect. For large Péclet number of permeation, it yields a rigorous support to the semi-empirical "film" model, and accounts for the limit flux phenomenon. The main results are summarized in a simple diagram that relates three different Péclet numbers, and show that polarization combined with osmosis can withstand operating pressure almost totally.
Pierre Haldenwang, Pierrette Guichardon, Guillaume Chiavassa, N. Ibaseta. Exact solution to mass transfer in Berman flow: application to concentration polarization combined with osmosis in crossflow membrane filtration. International Journal of Heat and Mass Transfer, 2010, 53 (19-20), pp.3898-3904. ⟨10.1016/j.ijheatmasstransfer.2010.05.008⟩. ⟨hal-00907275⟩
Journal: International Journal of Heat and Mass Transfer
