References of "Léonard, Angélique"
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See detailCoupling X-ray microtomography and macroscopic soil measurements: a method to enhance near saturation functions?
Beckers, Eléonore ULg; Plougonven, Erwan; Gigot, Nicolas et al

E-print/Working paper (in press)

Agricultural management practices influence soil structure, but the characterization of these modifications and consequences are still not completely understood. In this study, we aim at improving water ... [more ▼]

Agricultural management practices influence soil structure, but the characterization of these modifications and consequences are still not completely understood. In this study, we aim at improving water retention and hydraulic conductivity curves using both classical soil techniques and X-ray microtomography in the context of tillage simplification. We show a good match for retention and conductivity functions between macroscopic measurements and microtomographic information. Microtomography highlights the presence of a secondary pore system. Analysis of structural parameters for these pores appears to be significant and offers additional clues for objects differentiation. We show that relatively fast scans supply not only good results, but also enhance near saturation characterization, making microtomography a highly competitive instrument for routine soil characterization. [less ▲]

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See detailX-ray microtomography: A porosity-based thresholding method to improve soil pore network characterization?
Beckers, Eléonore ULg; Plougonven, Erwan ULg; Roisin, Christian et al

in Geoderma (2014), 219-220

X-ray microtomography, through quantification of soil structure at the microscale, could greatly facilitate the current understanding of soil hydrodynamic behaviour. However, binarisation method and ... [more ▼]

X-ray microtomography, through quantification of soil structure at the microscale, could greatly facilitate the current understanding of soil hydrodynamic behaviour. However, binarisation method and processing choices are subjective and can have a strong impact on results and conclusions. In this study, we test a new method based on the porosity detectable by X-ray microtomography, while validation is achieved through comparison of soil microtomogram information with soil physical measurements. These measurements consist of water retention and unsaturated hydraulic conductivity using two different soil populations with only structural differences. To assess the porosity-based method performances, we compare it to four other methods, namely the global method of Otsu and three recent soil-dedicated local methods. The robustness of the porosity-based method is also tested in regard to different pre-processing procedures. In this paper we demonstrate that soil segmentation through a porosity-based method is an interesting issue. Indeed, it is less demanding in terms of time and computational requirements than its alternatives, and combines robustness and performances broadly comparable with the recent local methods. [less ▲]

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See detailPreparation of polyaniline-modified local clay and study of its sorption capacity
Benhebal, Hadj; Chaid, Messaoud; Léonard, Angélique ULg et al

in Journal of Nanostructure in Chemistry (2014), 4(98), 6

Clay minerals are frequently used in adsorption processes with aqueous solution; it was found that the adsorption properties of clays change when the samples are modified. In this context, polyaniline ... [more ▼]

Clay minerals are frequently used in adsorption processes with aqueous solution; it was found that the adsorption properties of clays change when the samples are modified. In this context, polyaniline-modified clay nanocomposite (at 10 %) was prepared by in situ polymerization processes. The structural and morphological characteristics of the synthesized material are systematically examined by X-ray diffraction, scanning electron microscopy, thermo-gravimetry, differential scanning calorimetry and infrared spectroscopy techniques. The adsorption property of the modified clay was evaluated for the removal of a reactive dye (methylene blue) from aqueous solution at room temperature (25 C) via batch adsorption. [less ▲]

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See detailVisible-light photo-activity of alkali metal doped ZnO
Benhebal, Hadj; Chaib, Messaoud; Malengreaux, Charline ULg et al

in Journal of the Taiwan Institute of Chemical Engineers (2014), 45(1), 249-253

In order to utilize visible light more efficiently in the field of photocatalysis, Li, Na and K-doped ZnO nanoparticles were prepared using a sol–gel method. The obtained samples were characterized by BET ... [more ▼]

In order to utilize visible light more efficiently in the field of photocatalysis, Li, Na and K-doped ZnO nanoparticles were prepared using a sol–gel method. The obtained samples were characterized by BET surface area measurements, X-ray diffraction, scanning electron microscopy and UV–vis analysis. The photocatalytic activity of the photocatalysts was evaluated for the degradation of p-nitrophenol (p-NP) under visible light irradiation. It has been observed that these photocatalysts could be a promising photocatalyst for degradation of organic molecules as compared to transition metal doped ZnO under visible light. Li-doped ZnO is the most active photocatalyst and shows high photocatalytic activity for the degradation of p-nitrophenol (p-NP). The enhanced photocatalytic activity of Li-doped ZnO is mainly due to the electron trapping by lithium metal ions, small particle size, large surface area, and high surface roughness of the photocatalysts. [less ▲]

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See detailModeling and Simulation of Heat and Mass Transfer During Convective Drying of Wastewater Sludge with Introduction of Shrinkage Phenomena
Bennamoun, Lyes ULg; Fraikin, Laurent ULg; Léonard, Angélique ULg

in Drying Technology (2014), 32(1), 13-22

Wastewater sludge is dried in a convective dryer using air temperatures varying from 80°C to 200°C, velocities changing from 1 m · s−1 to 2 m · s−1, and humidities ranging from . The convective dryer is ... [more ▼]

Wastewater sludge is dried in a convective dryer using air temperatures varying from 80°C to 200°C, velocities changing from 1 m · s−1 to 2 m · s−1, and humidities ranging from . The convective dryer is equipped with a camera and an infrared pyrometer to follow respectively the external surface and the temperature of the product. The experimental results show that drying kinetic can be divided into three phases: two short first phases, called adaptation and constant drying phases, and a long third phase, called falling drying rate phase. As the moisture content decreases, the camera confirms simultaneous shrinkage effect with the volume reduction of the product of about 30–45% of the initial volume. Moreover, an increase of the product temperature towards air temperature was measured with the infrared pyrometer. In a second step of this study, the experimental results are modeled and simulated using heat and mass balances applied to the product and the heated air. The drying curve is rightly expressed with fourth-degree polynomial model with a correlation coefficient that approximates the unity and with low calculated errors. An outstanding determination of the heat transfer coefficient has permitted calculating the product temperature with good agreement with experimental results. The heat transfer coefficient expressed by means of Nusselt number is presented as a function of Reynolds and Prandlt numbers, changeable with air and product characteristics taking into account shrinkage effect. Moreover, as the applied air temperatures are sufficiently high, transfer by radiation is not neglected and is introduced in the mathematical model. [less ▲]

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See detailCharacterization of multi-walled carbon nanotube dispersion in resorcinol-formaldehyde aerogel
Haghgoo, Majid; Yousefi, Ali Akbar; Zohouriaan Mehr, Mohammad Jalal et al

in Microporous & Mesoporous Materials (2014), 184

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See detailModeling of Wastewater Sludge Drying with Determination of Diffusivity Moisture
Bennamoun, Lyes ULg; Fraikin, Laurent ULg; Salmon, Thierry ULg et al

in Journal of Residuals Science and Technology [=JRST] (2013), 10(4), 165

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See detail« Product-oriented engineering » applied to the development of porous scaffolds for tissue engineering.
de Bien, Charlotte ULg; Ounally, Thameur; Collard, Valérie ULg et al

Poster (2013, November 15)

Ce travail vise à appliquer une approche « génie-orienté produit » à la fabrication de matrices poreuses synthétiques (scaffolds) susceptibles d’être utilisées en ingénierie tissulaire [1]. Parmi les ... [more ▼]

Ce travail vise à appliquer une approche « génie-orienté produit » à la fabrication de matrices poreuses synthétiques (scaffolds) susceptibles d’être utilisées en ingénierie tissulaire [1]. Parmi les différents polymères biosourcés et biodégradables déjà utilisés pour la fabrication de scaffolds, l’acide polylactique (PLA) a été choisi [2]. Des matrices poreuses ont été obtenues par un procédé de moussage par lyophilisation puis leur microstructure 2D/3D a été caractérisée par microtomographie à rayons X avant d’être mise en lien avec les conditions d’élaboration testées [3]. La diminution de la porosité ainsi que l’augmentation de l’épaisseur des parois avec l’augmentation de rapport polymère/solvant ont été confirmées. [less ▲]

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See detailUse of Life Cycle Assessment to support in the Eco-Design of a glass-wool process
Gerbinet, Saïcha ULg; Renzoni, Roberto ULg; Briard, Vincent et al

Poster (2013, November 15)

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See detailEnvironmental Product Declaration of purified and defluorinated phosphoric acid – difficulties and limitations of the methodology
Belboom, Sandra ULg; Scözs, Carl; Léonard, Angélique ULg

Poster (2013, November)

The awareness of environment and the development of environmental product declarations (EPDs) are increasing through years. EPD becomes a need for producers in both B to B and B to C relations. EPD ... [more ▼]

The awareness of environment and the development of environmental product declarations (EPDs) are increasing through years. EPD becomes a need for producers in both B to B and B to C relations. EPD elaboration process is not without difficulties. Such a declaration requires a considerable amount of time and information, a full comprehension of the applied methodology but it also causes confidentiality problems. All these difficulties can lead to the use of simpler tools, as Carbon Footprint, which only focuses on a single impact and misses a part of the message. This case study is based on the production of phosphoric acid in Belgium using PCR for inorganic chemicals. It takes into account the use of raw materials as phosphate rocks or chemicals, their transportation to site and the manufacturing of defluorinated and purified phosphoric acid. This process also requires steam, electricity, demineralised water and sulphuric acid. These inputs are produced on site and their modelling is taken into account in this study. The first step of this process is the production of weak phosphoric acid with transformation of phosphate rocks into 30% phosphoric acid using sulphuric acid attack. The particularity of this process is the production, in this company, of a recoverable coproduct, called gypsum. The amount of this product is about 1.6 t per t of weak acid. A stoichiometric relation connects both products and is used as allocation factor, as recommended by the PCR. Through next concentration steps, fluosilicic acid is produced, also linked to the production of phosphoric acid by a stoichiometric relation. For facilities production plant, repartition of impact between coproducts is not so easy. As mentioned before, the production of steam, electricity, demineralised water and sulphuric acid are performed on site. Sulphuric acid is produced by the combustion of liquid sulphur provided by oil refineries. Two different units produce both sulphuric acid and steam through the combustion of liquid sulphur but only one of them transforms a part of steam into electricity. Repartition of impact between sulphuric acid and steam can be achieved using a physical relation based on thermodynamic values which can be transformed into mass relation. For repartition between electricity, steam and sulphuric acid, the main difficulty is that electricity does not have a weight and a transformation into steam shall be achieved to use the same relationship that previously. This way of allocating is not very obvious for producers, even if it is the one recommended by the PCR. As electricity and steam are coproduced, an energetic allocation is also relevant and gives completely opposite results for repartition of impact of each product. In that case, sulphuric acid impact achieves a non-negligible part of the impact which modifies greatly results of phosphoric acid production. This is a problem when you know that environmental product declarations are used to compare products on environmental criteria, using mainly values of climate change or energy impacts. Producers are then reticent to publish such a value which can lead to a loss of customer confidence, even more when they occupy a leading position on the market and taking into account that a comparison with other producers is quite impossible. More specific guidelines should be set to indicate the best way to perform an environmental product declaration in specific fields using a specific way of allocation. [less ▲]

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See detailDoes Belgian bioethanol comply with European Renewable Energy Directive ?
Belboom, Sandra ULg; Bodson, Bernard ULg; Léonard, Angélique ULg

Poster (2013, November)

The craze for biofuels has increased in recent years mainly to reduce greenhouse gas emissions and fossil fuel consumptions. The European Renewable Energy Directive (RED), published in 2009, defined ... [more ▼]

The craze for biofuels has increased in recent years mainly to reduce greenhouse gas emissions and fossil fuel consumptions. The European Renewable Energy Directive (RED), published in 2009, defined guidelines to assess carbon footprint of a biofuel depending on biomass source. It also provided generic values of GHG emissions relative to each step of the life cycle taking into account all steps from the cultivation to the end-of-life. These values are used to evaluate the sustainability of European biofuels depending on the used crops and the used transformation technology. This study, based on local crops cultivated in Belgium (sugar beet and wheat), compares specific Belgian values with European generic ones. Belgium yields for both crops are among the best of the continent. Specific Belgian values for fertilizers and pesticides are used. The transformation of wheat into bioethanol is modelled using industrial data. As recommended by the RED, no land use change is taken into account for Belgium. Greenhouse gas emissions induce by the life cycle of Belgium sugar beet bioethanol are similar to the ones mentioned in the European directive but impact repartition is different. In our case, the transformation step achieves a higher part of the impact. That can be explained by the higher cultivation yield. Belgian wheat bioethanol obtains better results than those mentioned by the European directive with a 9% higher reduction. Cultivation step is the major step for this impact. Importance of fertilizers consumptions and associated emissions are highlighted. The comparison of both bioethanols impacts for climate change category, using an energy basis, shows that wheat allows a higher reduction of GHG emissions than sugar beet. If the comparison is performed on a cultivated area basis, results are reversed and sugar beet achieves a twofold reduction compared with wheat. Sensitivity analyses are performed on the importance of N fertilizers and associated emissions and on energy consumptions relative to the transformation step. These analyses reveal non-negligible impact variations. A range of GHG reduction that can be reached using Belgian sugar beet and wheat bioethanol are then calculated. In any case, sugar beet does not achieve the amount of reduction given by the RED, while the opposite effect is shown for wheat with a reduction at least as high as the RED default value. These results indicate the importance of make use of specific values to assess the sustainability of bioethanol for a specific country using a specific crop and a specific technology. Further measurements and research about emission factors due to fertilizers application could improve the accuracy of our results. [less ▲]

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See detailLe « génie orienté produit » appliqué à l’élaboration de matrices poreuses pour l’ingénierie tissulaire.
de Bien, Charlotte ULg; Ounally, Thameur ULg; Collard, Valérie ULg et al

in Récents Progrès en Génie des Procédés (2013, October 08)

Ce travail vise à appliquer une approche « génie-orienté produit » à la fabrication de matrices poreuses synthétiques (scaffolds) susceptibles d’être utilisées en ingénierie tissulaire. Parmi les ... [more ▼]

Ce travail vise à appliquer une approche « génie-orienté produit » à la fabrication de matrices poreuses synthétiques (scaffolds) susceptibles d’être utilisées en ingénierie tissulaire. Parmi les différents polymères biosourcés et biodégradables déjà utilisés pour la fabrication de scaffolds, l’acide polylactique (PLA) a été choisi. Des matrices poreuses ont été obtenues par un procédé de moussage par lyophilisation puis leur microstructure 2D/3D a été caractérisée par microtomographie à rayons X avant d’être mise en lien avec les conditions d’élaboration testées. La diminution de la porosité ainsi que l’augmentation de l’épaisseur des parois avec l’augmentation de rapport polymère/solvant ont été confirmées. [less ▲]

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See detailBaker's yeast behavior during vacuum agitated contact drying
Bennamoun, Lyes ULg; Afzal, Muhammad; Léonard, Angélique ULg

in Chemical Engineering and Technology (2013), 36(10), 1795-1800

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See detailDifferent phases of water transfer during rock drying
Prime, Noémie ULg; Housni, Zakarya; Fraikin, Laurent ULg et al

Conference (2013, September 10)

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See detail"Product-oriented engineering" applied to the development of porous scaffolds for tissue engineering.
de Bien, Charlotte ULg; Ounally, Thameur ULg; Collard, Valérie ULg et al

in Procedia Engineering (2013, September 02)

This work applies a “product-oriented engineering” approach to the development of porous scaffolds for tissue engineering. Polylactic acid scaffolds were obtained by a freeze-drying process. Their 2D/3D ... [more ▼]

This work applies a “product-oriented engineering” approach to the development of porous scaffolds for tissue engineering. Polylactic acid scaffolds were obtained by a freeze-drying process. Their 2D/3D microstructure was characterized by X-ray microtomography and related to the operating conditions used. Two types of scaffold end-use properties were characterized in relation to their microstructure: the mechanical and the transport properties. Scaffold young's modulus was computed from data measured on tension-compression devices. To evaluate the permeability, Darcy’s experiments were carried out. The obtained results allowed highlighting the quantitative relationships existing between elaboration conditions, microstructure and end use properties of the fabricated PLA scaffolds. [less ▲]

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See detailHeat and mass transfer coefficient analysis during rock convective drying
Prime, Noémie ULg; Housni, Zakarya; Fraikin, Laurent ULg et al

Conference (2013, August)

This paper presents some experimental investigations about convective drying of rocks. Cylindrical samples made of limestone are dried from one their bases submitted to an air flow, while the other ... [more ▼]

This paper presents some experimental investigations about convective drying of rocks. Cylindrical samples made of limestone are dried from one their bases submitted to an air flow, while the other surfaces are hermetically covered. All other factors being equal, the influence of two parameters is looked after: the cylinder height, equivalent to the volume/surface ratio of the samples, and the direction of the air flow. The tests are interpreted both from the drying curves and from the values of water and heat transfer coefficients. Results first highlight that air flow incidence on the dried surface changes the kinetics and the transfer coefficient values. It can thus be supposed that the air flow direction would modify the thickness of the transfer limit layer at the surface and/or would make invalid the hypothesis of such a limit layer model for some flow configurations. Besides, the volume/surface ratio is shown to be correlated to the evaporation flux on the constant drying phase, and thus to the transfer coefficients. Nonetheless, this link tends to disappear from sufficiently high values of the volume/surface ratio since, in this case, the transfer coefficients reach constant values. This effect, in addition to other observations made on the drying curves, well fits with the hypothesis of a hydraulically connected layer below the drying surface, which would maintain during the constant drying rate phase. In the present case, this layer would have a thickness of around 20 to 30 mm. [less ▲]

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