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This paper presents the modelling and dynamic optimization of low pressure carburizing of steel. A cyclic hybrid model alternating two modes, i.e. the two stages of the process, boost and diffusion stages, is proposed. Each mode is characterized by a set of ordinary differential equations and its corresponding transition conditions and transition functions. The subsequent dynamic optimization problem is formulated and it aims to minimize the production of toxic compounds. The decision variables selected are the operating conditions, i.e. the lengths of boost and diffusion stages as well as the inlet flowrate of carburizing gas. Equality and inequality constraints are added on the state variables to ensure the quality of the treated steel parts. The resulting optimization problem of infinite dimension is transformed into a finite-dimension problem by means of the control vector parameterization approach and solved using a gradient-based method, i.e. sequential quadratic programming method. The solution algorithm is tested on an example and the optimal profiles yield satisfactory results.

This paper deals with the development of a geometry optimization approach to determine the optimal shape of a fixed-bed reactor where a catalytic surface reaction takes place. The investigated problem is formulated as a multi-objective optimization problem considering two antagonistic objectives: the energy dissipation in the fluid and the average concentration of reactant at the reactor outlet. The optimal solutions are subject to four constraints: (i) the process model consisting of the NavierStokes, the continuity and the convection-diffusion equations, (ii) an iso-volume constraint and (iii) two thickness constraints which allow us to take into account the manufacturability of the optimal reactors. The solution of the optimization problem is computed using the adjoint system method and the linear scalarization method which tranforms the multi-objective problem into a single-objective problem. The solution of the problem is a whole set of solutions (i.e. Pareto front) and the best optimal solution is chosen using the multi-attribute utility theory (MAUT). The best optimal shape of the reactor leads to a significant improvement of the conversion rate of 12.6% with respect to the initial shape and to an increase in energy dissipation 3.5 times higher.

This paper deals with the development of a thermodynamic-based model for the prediction of fouling phenomena in a wet phosphoric acid process. The developed model is based on mass and heat balances along with equations of Pitzer's thermodynamic model. It involves several unknown parameters that should be identified from experimental data. For this purpose, a database of experimental measurements carried out in this work, and other measurements from the literature are used. The comparison of the available measurements to the predictions generated using the values of the identified parameters shows the high performance of the developed model. Furthermore, the model is used to predict thermodynamic saturation indices of the main minerals that are likely to precipitate during the digestion process, and may cause fouling. A global sensitivity algorithm is finally used to determine the operating parameters that most influence the precipitation of these mineral phases. The results are very consistent with previous works and with the measurements carried out on industrial plants. Moreover, they explain many dysfunctions observed in phosphoric acid production facilities.

International audience; This paper focuses on the best way to produce methanol by Coke Oven Gas (COG) conversion and by carbon dioxide capture. The COG, produced in steelworks and coking plants, is an interesting source of hydrogen that can be used to hydrogenate carbon dioxide, recovered from flue gases, into methanol. The architecture of the reuse process is developed and the different process units are compared by considering a hierarchical decomposition. Two case studies are selected, process units are modelled, and flowsheets are simulated using computer-aided design software. A factorial techno-economic analysis is performed together with a preliminary carbon balance to evaluate the economic reliability and the environmental sustainability of the proposed solutions. The production costs of methanol are equal to 228 and 268 €/ton for process configurations involving, respectively, a combined methane reforming of COG and a direct COG separation to recover hydrogen. This cost is slightly higher than the current price of methanol on the market (about 204 €/ton for a process located in the USA in 2013). Besides, the second case study shows an interesting reduction of the carbon footprint with respect to reference scenarios. The carbon dioxide capture from flue gases together with COG utilization can lead to a competitive and sustainable methanol production process depending partly on a carbon tax.

International audience; Beta-nicotinamide adenine dinucleotide (NAD + /NADH) is an important enzymatic co-factor that can be efficiently regenerated using a rhodium-based catalyst as electron transfer mediator (i.e. [Cp*Rh(bpy)Cl] + , where Cp* = pentamethylcyclopentadienyl and bpy = 2,2-bipyridine). Here, the above mediated regeneration of NADH is implemented in a redox flow bioreactor hybridized with a gas diffusion electrode for hydrogen oxidation. The reactor was initially optimized with respect to rhodium complex and NAD + concentrations, humidification of the hydrogen gas, flow rates of both H 2 gas and electrolytic solution, and solution pH. The integration of an enzymatic reaction consuming the generated NADH was then investigated in a flow process, combining in series the electrochemical reactor to a biochemical cell with immobilized L-lactic dehydrogenase for the conversion of pyruvate to lactate. A high activity was achieved with a turnover number up to 370 h-1 for NADH regeneration. Coupled electrochemical regeneration to enzymatic reaction led to total turnover number values of 2000 and 6.3*10 6 for NADH electrochemical regeneration and bioconversion, respectively.

International audience; The management of water resources in a context of climate change, which increases the pressure on clean water availability, requires the development of monitoring tools to assess rapidly the quality of water and to characterize its eventual pollution. For several years now, optical methods have been proposed to monitor, without any reagent, different types of water: freshwater (rivers, lakes, etc.), estuarine water, seawater, groundwater, (polluted or not) as well as reclaimed water (which can be used for irrigation, cleaning, etc.), etc. Spectrophotometry and fluorescence spectroscopy can be combined usefully to characterize rapidly the global dissolved organic matter in water resources. Synchronous fluorescence, where the gap between excitation and emission wavelengths, is maintained constant during excitation wavelength scanning, is of particular interest.The objectives of the presentation are:-After a summary of the basic principles of synchronous fluorescence, the selection of the optimal gap between excitation and emission wavelengths will be discussed as well as ways to extract information out of the synchronous fluorescence spectra. -The combined use of synchronous fluorescence and spectrophotometry will be demonstrated using a large sample database covering large rivers (Seine, Danube, Moselle), headstreams (in mountains and plains), rivers suffering from large anthropogenic, agricultural and/or industrial pollution, reclaimed wastewaters, etc. Fig. 1. presents a subset of the database with synchronous fluorescence spectra collected along the Seine River. The characteristics extracted from the spectra will be discussed in function of classical pollution parameters. Fig. 1. Examples of synchronous fluorescence spectra collected along the Seine River

congrès virtuel; International audience

The sorption behavior of calcium silicate hydrate (CSH) with respect to lead, copper and zinc was studied to consider its application to remove metal from water runoff. A series of kinetics of removal and isotherms were undertaken with single metal and mixture solutions. The sorption occurred by ion exchange with calcium. Sorption kinetics were modelled using pseudo-second order model. The weight capacities of CSH were lead > copper >> zinc when studied separately. The co-ion associated to the metal ion is of importance on the removal capacities.

International audience

International audience; Fast-pyrolysis bio-oils (FPBOs) obtained from lignocellulosic biomass are gaining attention as sustainable fuels for various applications, including the transport sector and power production. A significant fraction of bio-oils is constituted by nitrogen-containing compounds (N fuels) that should be considered when developing surrogate models for FPBOs. Moreover, the content of N fuels in FPBOs is expected to strongly contribute to the production of nitrogen oxides (NOx) directly from fuel-bound nitrogen (fuel NOx), in addition to the thermal NOx formation pathways typical of high-temperature combustion conditions. This work investigates the pyrolysis and combustion chemistry of pyrrole (C4H5N), a candidate reference fuel component for FPBO surrogate models. Speciation measurements in an atmospheric pressure jet-stirred reactor have been performed for both pyrolysis and oxidation conditions. Pyrolysis experiments have been performed for 1% pyrrole/helium mixtures over the temperature range T = 925-1200 K. Oxidation experiments were carried out for 1% pyrrole/oxygen/helium mixtures at three equivalence ratios (φ = 0.5, 1.0, and 2.0) over the temperature range T = 700-1200 K. These new data significantly extend the number of experimental targets for kinetic model validation available at present for pyrrole combustion. After a thorough revision of previous theoretical and kinetic modeling studies, a preliminary kinetic model is developed and validated by means of comparison to new experimental data and those previously reported in the literature. The rate of production and sensitivity analyses highlight important pathways deserving further investigations for a better understanding of pyrrole and, more in general, N fuel combustion chemistry. A critical discussion on experimental challenges to be faced when dealing with pyrrole is also reported, encouraging further experimental investigation with advanced diagnostics.

congrès en ligne; International audience

Hypothesis The distribution of particles in Pickering emulsions can be estimated through a percolation-type approach coupled to the evolution of their rheological features with the dispersed phase volume fraction ϕ. Experiments The rheological behavior of water-in-dodecane Pickering emulsions stabilized with hydrophobic silica nanoparticles is addressed. The emulsions viscosity and elastic modulus are investigated at ϕ varying from 0.1 to 0.75. Various rheological models are adjusted to the experimental data. Findings The comparison of the elastic modulus evolution of the Pickering emulsions with those of emulsions stabilized with surfactants confirms a major contribution of the particles to the rheological behavior of Pickering emulsions and supports the existence of a three-dimensional network between the droplets. The applied percolation approach allows to quantitively estimate a nanoparticles viscoelastic link between the droplets and opposes the classic vision of interfacial monolayers stabilizing the Pickering emulsions. This network of interconnected particles and droplets contributes significantly to the viscosity as well as the elastic modulus of these emulsions. To our knowledge, the applied percolation-based model is the only one capable of providing a structural explanation while describing the abrupt viscosity and elastic modulus growth of Pickering emulsions across the range of ϕ.

International audience; A single source molecular precursor synthesis of new quinary Ag-In-Ga-Zn-S (AIGZS) QDs is presented. Dithiocarbamate complexes with varied Ag/In/Ga/Zn ratios were prepared from AgNO3, In(NO3)3, Ga(NO3)3 and Zn(diethyldithiocarbamate)2. The thermal decomposition of these complexes at 220°C in oleylamine produces AIGZS QDs emitting from the visible to the near-infrared region and with photoluminescence quantum yields (PL QYs) up to 48.3%. For AIGZS QDs prepared with a (Ag + In + Ga)/Zn molar ratio of 1, intragap states likely involving Ag + ions are responsible of the PL emission and the PL lifetime could reach 278 ns. A marked increase of the PL lifetime (up to 915 ns) was observed when decreasing the (Ag + In + Ga)/Zn molar ratio to 0.5. The optical properties of AIGZS QDs could be maintained after transfer in aqueous solution. AIGZS should be of high potential for various applications due to their PL emission tunability and high PL QYs.

International audience; The design of sustainable energy systems requires to enlarge the analysis beyond the traditional boundaries for including the economic, environmental, and societal needs and constraints in the decision-making process. In this regard, this work investigates the conceptual design of distributed energy systems by means of a multi-objective optimization strategy to simultaneously address the economic, environmental, and social aspects in the energy system design. Initially, the water consumption and the inherent safety indicators were introduced and evaluated through two single-objective optimization problems to enhance the analysis of the environmental and social dimensions of sustainability. Then, a framework including the total annualized cost, CO2 emissions, water consumption, grid dependence, and inherent safety index was used to perform the multi-objective analysis. To carry out a thorough and comprehensive analysis, four optimization problems including different combinations of the sustainability indicators were proposed and solved. The compromise among the objective functions was identified, and the obtained Pareto sets were explored for elucidating the changes in the design and operating conditions across the non-dominated solutions. According to results, the cost of energy can range between 0.37 and 0.63 €/kWh, the CO2 emissions can vary between 10.6 and 68.5 kgCO2/MWh, and the water consumption can be between 27.8 and 70.2 m3H2O/GWh depending on the evaluated objective. Moreover, it was determined that the safety of the energy system can be improved by increasing the use of the water electrolysis pathway to produce hydrogen and by reducing the capacity of the hydrogen storage unit.

Refractory pollutants often exist in wastewater after photocatalysis. Here, experiments, gas chromatography-mass spectrometry (GC–MS) analysis and density functional theory (DFT) simulations were used to explain the different levels of photocatalytic degradation of organics in papermaking wastewater associated with two photocatalytic processes with the goal of improving environmental sustainability. The photocatalytic experiments of flocculation and SBR effluents of papermaking wastewater were studied in a reactor with nano-TiO2 colloid, followed by GC–MS analysis, and the different degradation levels of organics were explained based on DFT adsorption and photocatalysis simulations. The experimental results show that the total COD removal rates were 65.8% and 90.8% for the flocculation-photocatalysis and SBR-photocatalysis processes, and the resin acids and fatty acids in wastewater were classified as easily degradable pollutants and esters as refractory pollutants. The adsorption and photocatalysis simulations show that compared with dehydroabietic acid and pentadecanoic acid, the adsorption of glycerol monostearate by nano-TiO2 colloid is difficult, the reaction pathways for photocatalysis are complex and the band gap of TiO2 photocatalyst after adsorption is wide. The experimental and simulation results indicate that the different degradation levels are attributed to the difficulty of the adsorption and photocatalytic reactions of glycerol monostearate compared with the reactions of the other two easily degradable pollutants. Thus, the different photocatalytic degradation levels of organic pollutants in the two photocatalytic processes of papermaking wastewater indicate that sustainable photocatalytic technology could be applied to different types of industrial wastewater.

The direct capture of CO2 from air (DAC) has been shown a growing interest for the mitigation of greenhouse gases but remains controversial among the engineering community. The high dilution level of CO2 in air (0.04%) indeed increases the energy requirement and cost of the process compared to carbon capture from flue gases (with CO2 concentrations around 15% for coal power plants). Until now, solid sorbents (functionalized silica, ion exchange resins, metal–organic frameworks, etc.) have been proposed to achieve DAC, with a few large-scale demonstration units. Gas-liquid absorption in alkaline solutions is also explored. Besides adsorption and absorption, membrane processes are another key gas separation technology but have not been investigated for DAC yet. The objective of this study is to explore the separation performances of a membrane unit for CO2 capture from air through a generic engineering approach. The role of membrane material performances and the impact of the operating conditions of the process on energy requirement and module production capacity are investigated. Membranes are shown to require a high selectivity in order to achieve purity in no more than two stages. The specific energy requirement is globally higher than that of the adsorption and absorption processes, together with higher productivity levels. Guidelines on the possibilities and limitations of membranes for DAC are finally proposed.

The kinetics of the hydrolysis and polycondensation reactions of saccharides have made the subject of numerous studies, due to their importance in several industrial sectors. The present work, presents a novel kinetic modeling framework that is specifically well-suited to reacting systems under strict moisture control that favor the polycondensation reactions towards the formation of high-degree polysaccharides. The proposed model is based on an extended and generalized kinetic scheme, including also the presence of polyols, and is formulated using two different numerical approaches, namely a deterministic one in terms of the method of moments and a stochastic kinetic Monte Carlo approach. Accordingly, the most significant advantages and drawbacks of each technique are clearly demonstrated and the most fitted one (i.e., the Monte Carlo method) is implemented for the modeling of the system under different conditions, for which experimental data were available. Through these comparisons it is shown that the model can successfully follow the evolution of the reactions up to the formation of polysaccharides of very high degrees of polymerization.

Catalytic oxidation of propylene to acrolein is usually performed in a multi-tubular fixed bed catalytic reactor at industrial scale. Nevertheless, the production of side products is not optimal as well as the use of molten salt to cool the reactants. This is mainly due to heat transfer issues resulting of the high exothermicity of the reactions. This paper deals with the reactor intensification for the propylene oxidation on a solid bismuth/molybdate catalyst. A simple but robust power law kinetic model, based on the recent published literature, is first proposed, and kinetic parameters are identified by comparison between experiments performed on an isothermal micro fixed bed catalytic reactor and simulations obtained from a pseudo-homogeneous reactor model. The determined parameters are in good agreement with published ones. This kinetic model is then used for the design of an intensified heat-exchanger reactor (HEX reactor). This device consists in several reactive catalyst washcoated channels alternatively distributed with coolant channels. Three performance parameters (acrolein yield, propylene conversion and maximal temperature elevation) are defined, and their variations against process parameters are determined in order to size the HEX reactor and to identify optimal process conditions, for a given feed flow rate.

Faced with the growing need for new bioactive compounds of natural origin, by-products from the agro-food industry and the processing of agro-resources constitute a strategic resource to be exploited. In fact, the enzymatic hydrolysis of plant or animal proteins makes it possible to generate a wide variety of peptide sequences with potential biological properties: antihypertensive, antithrombotic, anticancer, opioid, antimicrobial. Despite the bioactive potential of certain peptides, their uncertain presence and their low concentration in a protein hydrolysate (a complex mixture sometimes made up of more than a hundred peptides) limit their purification and use. Also, bioactive peptides could be screened before their purification in order to initiate the separation step only if activity is proven. Antioxidant power is a generic term which groups together various chemical mechanisms such as anti-free radical activity, inhibition of lipid peroxidation, or even metal chelation. By chelating the transition metals naturally present in vivo (iron, copper), the chelating peptides could be used as indirect antioxidants and thus act against oxidative stress. The main objective of this PhD thesis is to develop original methods for high throughput screening of iron-chelating peptides present in protein hydrolysates. Ultimately, these methods could be applied to all types of complex peptide mixtures. The first approach is based on immobilized metal affinity chromatography (IMAC). IMAC is a reference technique for purifying metal-chelating peptides in hydrolysates. Thanks to the specificity of interaction between a given metal – immobilized on the stationary phase IMAC – and determined complexing groups, it is possible to selectively identify the chelators present in complex mixtures. Our objective being to achieve a rapid detection of these molecules of interest, we carried out an on-line coupling with mass spectrometry (MS). The second strategy consists of evaluating the formation of iron-peptide complexes in solution. In this case, all the electron acceptor sites of the metal are accessible (unlike the IMAC technique which presents a potential bias from this point of view) and, on the other hand, the solubilization conditions can simulate the target medium (i.e. the intracellular medium). In addition, the observation of the peptidic form complexed with iron (FeII or FeIII) provides direct and irrefutable proof of the chelating capacity of a peptide. Thus, the identification of a chelating peptide can be carried out by the concomitant detection of its free form (peptide) and of its complexed form (iron-peptide). In this approach, mass spectrometry – thanks to its sensitivity and its specificity - is a technique of choice for carrying out the desired screening. After having been tested on synthetic peptides (pure solutions and mixture), the two protocols were applied to a real protein hydrolysate. The preliminary results are promising and make it possible to envisage, in the short term, the automated screening of various real hydrolysates for the search for iron(II)- and iron(III)-chelating peptides., Face au besoin croissant de nouvelles molécules bioactives d’origine naturelle, les coproduits de l’industrie alimentaire et de transformation d’agroressources constituent une ressource stratégique à exploiter. En effet, l’hydrolyse enzymatique de protéines végétales ou animales permet de générer une grande variété de séquences peptidiques avec des propriétés biologiques potentielles : antihypertensive, antithrombotique, anticancéreuse, opioïde, antimicrobienne. Malgré le potentiel bioactif de certains peptides, leur présence incertaine et leur faible concentration au sein d’un hydrolysat protéique (mélange complexe constitué d’une dizaine à parfois plus d’une centaine de peptides) limitent leur purification et leur exploitation. Aussi, les peptides bioactifs pourraient être criblés préalablement à toute phase séparative afin de n’engager l’étape de séparation qu’en cas d’activité avérée. Le pouvoir antioxydant est un terme générique qui regroupe divers mécanismes chimiques tels que l’activité anti-radicalaire, l’inhibition de la peroxydation des lipides, ou encore la chélation de métaux. En chélatant les métaux de transition naturellement présents in vivo (fer, cuivre), les peptides chélateurs pourraient être utilisés comme antioxydants indirects et agir ainsi contre le stress oxydant. L’objectif principal de cette thèse est de développer des méthodes originales de criblage à haut débit des peptides chélateurs de fer présents dans des hydrolysats peptidiques. A terme, ces méthodes pourraient être appliquées à tous types de mélanges peptidiques complexes. La première approche développée met en œuvre la chromatographie d'affinité pour ions métalliques immobilisés (IMAC). Cette technique est incontournable pour purifier des peptides chélateurs de métaux au sein des hydrolysats. Grâce à la spécificité d’interaction entre un métal donné – immobilisé sur la phase stationnaire IMAC – et des motifs complexants déterminés, il est possible d’identifier sélectivement les composés chélateurs présents dans des mélanges complexes. Notre objectif étant de parvenir à une détection rapide de ces molécules d’intérêt, nous avons réalisé un couplage en ligne avec la spectrométrie de masse (MS). La deuxième stratégie consiste à évaluer la formation des complexes fer-peptide en solution. Dans ce cas, tous les sites accepteurs d’électrons du métal sont accessibles (au contraire de la technique IMAC qui présente un biais potentiel de ce point de vue) et, d’autre part, les conditions de solubilisation peuvent simuler le milieu visé (i.e. le milieu intracellulaire). Par ailleurs, l’observation de la forme complexée avec le fer (FeII ou FeIII) fournit une preuve directe et irréfutable de la capacité de chélation d’un peptide. Ainsi, la mise en évidence d’un peptide chélateur peut être réalisée par détection concomitante de sa forme libre (peptide seul) et de sa forme complexée (fer-peptide). Dans cette approche, la spectrométrie de masse – de par sa sensibilité et sa spécificité – est une technique de choix pour réaliser le criblage souhaité. Après avoir été testés sur des peptides des synthèse (sous forme pure et en mélange), les deux protocoles ont été appliqués à un hydrolysat protéique réel. Les résultats préliminaires obtenus sont prometteurs et permettent d'envisager, à court terme, le criblage automatisé de divers hydrolysats réels, pour la recherche de peptides chélateurs du fer(II) et du fer(III).

International audience

International audience; Explosion hazards do not only include gases, vapors and dusts, but also mists. Indeed, previous incident surveys identified dozens of accidents related to hydrocarbon mists generation and ignition. The ongoing occurrence of mist explosions demonstrates the need to assess the relevance of the current approaches for the evaluation of the mist ATEX risks and to determine reliable and standardized safety parameters for hydrocarbon mists. For this study, different fluids with a high industrial interest were selected (e.g. ethanol, kerosene, and diesel) to be tested in a new apparatus based on the standardized 20L explosion sphere. A new fluid injection system was deployed using siphon/gravity-fed spray nozzles comprising a Venturi junction and proposing a wide variety of dispersion performances. This system was controlled using a specifically dedicated program, which ensures the versatility of the apparatus and its adaptability to the different liquids tested. It allows a fine control of the gas carrier flow, the liquid flow and both the injection and ignition times, which makes it possible to change the dilution rate for a desired droplet size distribution. The droplet size distribution (DSD) was determined for the various fluids dispersed into the 20L sphere. Several tests were performed to determine the minimum ignition energy (MIE), the lower explosivity limit (LEL), the maximum explosion pressure (Pmax) and the maximum rate of pressure rise (dP/dt max) of hydrocarbon mists. For instance, for a DSD centered at 55μm, a maximum pressure of 9.2 bar and maximum rate of pressure rise up to 600 bar.s-1 were found for ethanol. As for kerosene, for a DSD centered at 80μm, 8.8 bar and 570 bar.s-1 were found respectively. Experimental results obtained between the LEL and the stoichiometric concentration were compared with numerical data obtained with Chemical Equilibrium with Applications and showed that they were coherent with the theoretical calculations and that tests were at least performed up to the stoichiometric concentration. A sensitivity analysis was conducted to stress the influence of parameters such as the chemical nature of the fuel, the DSD, the ignition energy or the mist temperature (gas/mist ratio). For instance, tests performed on kerosene showed that as the DSD increases, the mist cloud becomes harder to ignite and hence the LEL increases. These first results already allow to propose a new protocol to determine safety parameters for hydrocarbon mists and provide tools to support the evaluation of mist ATEX risks.

International audience; In zinc hydrometallurgy, hot-acidic leaching of calcines leads to Fe/Zn solutions in sulfuric acid medium. Three distinct processes have been previously developed to remove iron: jarosite, goethite and hematite. Each process displays their own drawbacks: important loss of zinc (jarosite, goethite), significant environmental impact of residue (jarosite) or economic cost (hematite). The work reported herein investigated the possibility of using phytic acid, a compound extractable from cereals, to remove iron. Precipitation was studied first at the laboratory-scale using DOE methodology and then with a laboratory pilot. At pH = 2.1, we showed that it is possible to remove up to 99.5% of iron with a loss of zinc equal to 0.6% and a residual concentration of FeIII of 130 mg L−1. Even if the amount of residue is more important than in the jarosite process, leaching tests showed that iron phytate could be stored in less drastic conditions than jarosite.

International audience

International audience; Avec la fabrication additive il est possible de générer des formes complexes, organiques et des structures en treillis ou à base de plusieurs matériaux. Sur cette base, l’impression 4D a émergé dès 2013 pour donner « vie » aux objets 3D, exploitant ainsi les techniques de fabrication par ajout de matière et les matériaux dits actifs ou intelligents. Cet article présente l’état de l’art concernant des matériaux actifs et leur réponse aux stimuli en termes de propriétés, formes et fonctionnalités, ainsi que leur interaction avec les procédés de fabrication additive. La démarche permet d’identifier des limites et le potentiel de cette technologie en devenir. L’article discute des verrous scientifiques, techniques et organisationnels à relever pour rendre ce paradigme émergent opérationnel et adoptable par les divers métiers de l’industrie

International audience; Using a synthetic method, the phase behavior of the CO2 (1) + cyclooctane (2) binary system was for the first time experimentally studied between 292.95 K and 373.55 K. In this temperature range, the bubble- and dew-point pressures, ranging from 13.2 to 183.4 bar were measured for carbon dioxide mole fractions between 0.1014 and 0.9701. A total of 96 experimental data points were acquired. The experimental data were obtained using a high-pressure cell by visual observation of phase transitions. These measurements made it possible to conclude that the studied binary system probably exhibits a type V phase behavior in the classification scheme of Van Konynenburg and Scott. In particular, the experimental temperature of the suspected lower critical end point (LCEP) was found to be 303 K. Despite the complexity of the phase behavior, the experimental data could be accurately correlated with the Peng-Robinson equation of state combined with sophisticated mixing rules that either involve temperature-dependent binary interaction parameters (kij(T)) or that embed the residual part of the Wilson activity coefficient model.

International audience; X-ray-induced photodynamic therapy is based on the energy transfer from a nanoscintillator to a photosensitizer molecule, whose activation leads to singlet oxygen and radical species generation, triggering cancer cells to cell death. Herein, we synthesized ultra-small nanoparticle chelated with Terbium (Tb) as a nanoscintillator and 5-(4-carboxyphenyl succinimide ester)-10,15,20-triphenyl porphyrin (P1) as a photosensitizer (AGuIX@Tb-P1). The synthesis was based on the AGuIX@ platform design. AGuIX@Tb-P1 was characterised for its photo-physical and physico-chemical properties. The effect of the nanoparticles was studied using human glioblastoma U-251 MG cells and was compared to treatment with AGuIX@ nanoparticles doped with Gadolinium (Gd) and P1 (AguIX@Gd-P1). We demonstrated that the AGuIX@Tb-P1 design was consistent with X-ray photon energy transfer from Terbium to P1. Both nanoparticles had similar dark cytotoxicity and they were absorbed in a similar rate within the cells. Pre-treated cells exposure to X-rays was related to reactive species production. Using clonogenic assays, establishment of survival curves allowed discrimination of the impact of radiation treatment from X-ray-induced photodynamic effect. We showed that cell growth arrest was increased (35%-increase) when cells were treated with AGuIX@Tb-P1 compared to the nanoparticle doped with Gd

The aim of this study was to valorize liquid effluent from the sunflower protein isolate process by extracting phenolic compounds it contains. To do so, XAD7 resin was used. A multicriteria optimization methodology based on design of experiments showed the optimal conditions were adsorption flow rate of 15 BV/h at pH 2.7, a desorption flow rate at 120 BV/h with ethanol/water 50% (v/v). The best trade-off between purity and recovery yields resulted in the production of a fraction containing 76.05% of chlorogenic acid (CGA) whose biological properties were evaluated. DPPH and ABTS tests showed that this fraction had a higher radical scavenging capacity than vitamin C. In vitro assays have shown that this fraction, when used at a concentration corresponding to 50 or 100 µM of CGA, does not present any cytotoxicity on human THP-1 cells differentiated into macrophages. In addition, this fraction when added prior to the inflammatory stimulus (LPS) can reduce tumor necrosis factor-alpha (TNF-α) production by 22%, thereby highlighting its protective properties against future inflammation.

Pesticides are used worldwide in large quantities to increase yield in agriculture. On the other hand, they are in general toxic/persistent organic pollutants presenting strong adverse effects to the environment and human health, including acute and chronic toxicity. Consequently, water polluted by pesticides should be treated efficiently before its release into receiving water bodies to protect the natural aquatic environment. Different methods have been used for the treatment of water contaminated by pesticides. Among them, electrochemical technology seems to be very efficient in removing pesticides from water. Therefore this review aims to provide an overview of the recent works on the treatment of pesticide wastewater using electrochemical technology with a special focus on electrochemical advanced oxidation processes that demonstrated high efficiency in the removal of various types of pesticides from contaminated water.

International audience; When possible, the bioprocesses should be implemented to treat wastewater for their cost-effectiveness. However, many effluents are composed of biorecalcitrant organic pollutants, especially in industrial wastewaters. Advanced physico-chemical treatments are therefore needed to deal with these pollution levels. Electrochemical processes could be cost-effective solutions. However, the energy required to reach complete mineralization is often high. One promising combination would be to combine electrochemical processes that can remove xenobiotic compounds from effluent with biotechnologies that are able to mineralize the biodegradable fraction. Therefore, this review presents the most recent articles dealing with this combination, by mainly focusing on electrochemical advanced oxidation processes that demonstrated to have high removal efficiency for organic biorecalcitrant compounds. Additional and imperative information about the treatment strategy and the engineering aspects for the upscaling approach are also given.

International audience

The self-sustained coalescence-breakup cycles of ferrodrops were investigated for the first time by a high-speed camera under various magnetic fields. Under an axial magnetic field, the upper ferrodrop would deform into a conic shape before coalescing with the bottom ferropeak. Within 0.2 ms after coalescence, the minimum width of the expanding neck obeys a power-law relationship with time, while the exponents increase with the magnetic field and deviate with a decreasing trend in the later coalescence. The cone angle of the upper ferrodrop before coalescence gradually decreases while it increases before breakup with the magnetic field. A critical magnetic field around 35 mT was reported, above which the ferrofluid column undergoes the periodic phenomenon of coalescence and breakup. The frequency for the whole coalescence-breakup cycle increases exponentially with the applied magnetic field. A simplified force balance allows capturing the periodic mechanism involved in this driven harmonic oscillator.

Large-scale mesenchymal stem/stromal cells culture uses 3D culture systems involving spherical solid particles, called microcarriers. Cells adhere on these spheres, which are then set in suspension in stirred tank bioreactors. This work was more particularly focused on the determination of the critical impeller agitation rate N js , allowing complete beads suspension. It is indeed generally assumed that this value is a good compromise between sufficient nutrients homogenization, mass transfer and minimization of hydromechanical stress encountered by the cells. However, no robust correlation predicting N js in the case of microcarriers can be found in literature. To fill this lack, a set of various operating conditions was carried out, dealing with geometrical variables and two different microcarriers, and N js were experimentally determined for 140 conditions. An empirical correlation was established and a dimensional analysis was performed, showing that the impact of the particle concentration on N js was function of the impeller design. Moreover, two dimensionless numbers characterizing the number of particle and an Archimede number applied on the particle cloud were found to better describe the impact of particle diameter and density on N js . Simultaneously, a strategy based on Computational Fluid Dynamics simulations was conducted in order to predict N js and was validated with the N js experimental values.

International audience; The aim of this paper is to review recent progress in detection and quantification of hydroperoxides, and to understand their reaction kinetics in combustion environments. Hydroperoxides, characterized by an-OOH group, are ubiquitous in the atmospheric oxidation of volatile organic compounds (~300 K), and in the liquid and gas phase oxidation of fuel components at elevated temperatures (~400-1000 K). They are responsible for two-stage fuel ignition in internal combustion engines and they play an important role in the formation and evolution of secondary organic aerosols in the atmosphere. The introduction outlines the importance of hydroperoxide chemistry in combustion reaction processes. In addition to this main topic, the role of hydroperoxide in atmospheric and liquid phase oxidation chemistry is also introduced, for a more general perspective. The second part of this paper briefly reviews the mechanistic insights of hydroperoxide chemistry in combustion systems, including experimental detection of these reactive species before 2010. Since that time significant progress has been made by advanced diagnostic techniques like tunable synchrotron vacuum ultraviolet photoionization mass spectrometry and infrared cavity ring-down spectroscopy. The third chapter of this work summarizes progress in gas phase oxidation experiments to measure hydrogen peroxide, alkyl hydroperoxides, olefinic hydroperoxides, ketohydroperoxides, and more complex hydroperoxides that include as many as five oxygen atoms. The fourth section details recent advances in understanding the combustion chemistry of hydroperoxides, involving the formation of carboxylic acids and diones, as well as the development of oxidation models that include a third O2 addition reaction mechanism. Finally, challenges are discussed, and perspectives are offered regarding the future of accurately measuring molecule-specific hydroperoxide concentrations and understanding their respective reaction kinetics.

International audience; Dextran-covered poly(D,L-lactide) (PLA) nano-and microparticles were prepared by emulsion/solvent evaporation (or diffusion) process with the aim of encapsulating alkyl gallates (AGs). In the first step, a solution of PLA and AG in ethyl acetate was emulsified into an aqueous phase containing a hydrophobically modified dextran which acted as stabilizer. The second step consisted in solvent evaporation or diffusion. Emulsification conditions were varied which allowed preparing nano-and microparticle suspensions covering a wide range of surface-average particle diameters between 0.1 µm (in the case of sonication) and 500 µm (in the case of stirring with magnetic barrel) with narrow and reproducible size distributions. Continuous microfluidic emulsification in a flow focusing system led to well-defined microparticles, within the 10-50 µm range. Particles loaded with octyl gallate (OG) and nonyl gallate (NG) were obtained with the three processes and we showed that the encapsulation efficiency of OG and NG varied significantly according to emulsification process. The effect of particle size on the mechanism of in vitro release of encapsulated AGs was investigated. According to the pH of external medium, the kinetics of release was controlled either by Fickian diffusion within solid core or by swelling and hydrolytic degradation of PLA matrix.

International audience

International audience; The removal of hazardous organic micropollutants in municipal wastewater treatment plants (WWTP) has become a common concern for public decision‐makers and stakeholders. An advanced electro‐oxidation with boron‐doped diamond (BDD) anode material is proposed to remove acetaminophen as a representative micropollutant in synthetic solution. A customized microfluidic reactor was run in batch mode, and the main operating parameters (i. e. current density, interelectrode distance and solution conductivity) were optimized by minimizing the energy requirement. An optimal current density of 4 mA cm−2 and an optimal interelectrode distance of 500 μm were newly obtained and explained. Mass transport limitation was observed at lower gaps, with a 3.4‐fold decrease in the mass transfer coefficient from 500 μm to 50 μm intervals. In addition, the kinetics of degradation decreased dramatically after a certain electrolysis time. This was attributed to the increase in gas bubble production with treatment time. An increase in the solution conductivity from 0.23 to 2.0 mS cm−1 increased the degradation rate efficiency twofold and decreased the specific energy from 0.88 to 0.17 kWh g−1 at 85 % acetaminophen decay yield. The influence of a real matrix from low‐conductivity reclaimed WWTP (0.86 mS cm−1) highlighted slightly lower kinetics of degradation, but similar energy efficiency until 60 % of pollutant degradation and higher energy efficiency than in conventional macro‐reactors.

International audience; The pyrolysis of a halogenated ester, methyl chloroacetate (MC), under dilute atmosphere and quasi-atmospheric pressure was studied at temperatures from 473 to 1048 K using an alumina tubular reactor. MC was chosen as a surrogate to model the thermal decomposition of ethyl bromoacetate, a chemical warfare agent. A maximum MC conversion of 99.8% was observed at a residence time of 2 s, a temperature of 1048 K, and an inlet mole fraction of 0.01. The following products were quantified: CO, CO2, HCl, methane, ethylene, ethane, propene, chloromethane, dichloromethane, vinyl chloride, chloroethane, and dichloroethane. For the first time, a detailed kinetic model of MC pyrolysis was developed and gave a good prediction of the global reactivity and the formation of most of the major products. Flow rate and sensitivity analyses were made to highlight the different pathways of decomposition during the MC pyrolysis. In a first attempt to extrapolate the results obtained with methyl chloroacetate to ethyl bromoacetate, simulations were run with a modified version of the model developed in this study taking into account the differences in bond dissociation energies induced by the change of the chlorine atom by a bromine one.

Photodynamic therapy has become of interest in many European countries. Since, most of national authorities and all medical journals require the registration of the clinical study on the database ClinicalTrials. gov in order to be published, information regarding clinical studies are now available. This article aims to synthetize data gathered thanks to this database. The keywords used for this analysis was: (i) status: “All studies “(recruiting, completed, terminated, we did not take into account unknown status), (ii) condition or disease: “Photodynamic Therapy”, (iii) country: name of each European country. Since 2003, 76 clinical trials were registered in Europe. Most clinical studies are performed in Germany (22), France (20) and UK (19). These 3 countries represent 80% of all studies performed in Europe. However 21 European countries have one or more studies on PDT. Clinical studies were mainly performed on skin. Actinic Keratosis treatment (20 studies) represents more than 45% of all studies. 21% were focused on eye, mainly on Age Macular Degeneration (AMD) (8 studies). In 2018, ten (10) clinical trials are in the recruitment phase. On November, 10, 2017, Padeliporfin (STEBA Biotech S.A, Luxembourg) obtained the marketing authorization throughout the European Union. Despite the critical importance of trial registration, compliance with requirements from governmental regulators which mandate the prospective registration of clinical trials has been imperfect. Besides, a large proportion of registry entries are never updated to reflect study completion. However, this review clearly demonstrated that PDT is progressively used in most European countries.

International audience; The so-called Graftfast reaction in water and at room temperature (RT) was applied to graft polyethylene glycol (PEG) at the surface of the microporous zeolitic imidazolate framework ZIF-8 nanoparticles (NPs) using acrylPEG of different chain lengths (480 Da and 5 kDa). In comparison to non-modified ZIF-8 NPs, both chemical and colloidal stabilities of PEGylated ZIF-8 NPs are significantly enhanced in water. A series of colloidal complex fluids by mixing PEG grafted ZIF-8 (i. e. PEG-g-ZIF-8) NPs with different amounts of polyvinylalcohol (PVA) was prepared and characterized by advanced characterization tools such as dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) thereby showing their long-term colloidal stability. Finally, dense and supported mixed matrix membranes were cast from PEG-g-ZIF-8/PVA solutions and have shown high performance in isopropanol (IPA) dehydration by pervaporation. The permeation flux of the supported MMM (i. e. 0.091 kg/(m$^2$h) is eleven times higher than that of the pure PVA membrane and these MMMs present a high separation factor (i. e. 7326). These transport properties are presumably due to the molecular sieving effects induced by ZIF-8 and the good interfacial properties of the membrane. The computational exploration of the ZIF-8/PVA and PEG/PVA interfaces provides a microscopic scale explanation for the enhanced compatibility of PVA with the PEGylated MOF when compared to that for the composite based on the bare ZIF-8 as a filler.

The purpose of this research work is to determine the maximum single carbon number (SCN) which can be reliably quantified using High Temperature Gas Chromatography (HTGC) analysis of heavy oil hydrocarbons, accounting for (i) thermal cracking risk and (ii) the non/incomplete elution. To that end, an in-house coupled numerical Pyrolysis-GC model has been developed, capable of calculating the degree of elution and of simulating the migration, partitioning, and pyrolysis conversion of a mixture of 11 heavy n-alkanes spanning the range from nC14H30 to nC80H16 throughout the GC column. On the basis of this model and using a commonly used column configuration and temperature program, two conclusions have been made: (i) half of the mass injected of nC80 thermally decomposed before nC70 has eluted, suggesting a possible coelution of both nC70 and the pyrolysis products of nC80 and therefore making the HTGC analysis of nC70 and heavier n-alkanes no longer reliable, and (ii) alkanes heavier than nC70 take progressi...

In carbon capture processes based on chemical absorption, the solution used for absorbing carbon dioxide plays a central role and must be carefully selected. It is expected to have the potential to capture large amounts of carbon dioxide on the one hand, and to be fully regenerated at the lowest energy price on the other hand. As a continuation of a study initiated by Coulier et al. some years ago, the present work focuses on the measurement and modeling of thermodynamic properties of aqueous solvents containing methylpiperidines (a class of amines), potentially usable in carbon capture processes and leading to liquid–liquid phase split in process conditions. To complete liquid–liquid equilibrium (LLE), excess enthalpy and excess heat capacity data previously measured by Coulier et al. for the N-methylpiperidine + water and 2-methylpiperidine + water systems, LLE data, and excess-enthalpy data were measured for the 3-methylpiperidine + water and 4-methylpiperidine + water systems. To model all these data,...

The evolution of the size and velocity of CO2 bubble absorbed into MEA/[Bmim][BF4] aqueous solutions was in-line investigated by a high-speed camera. The coupling effect between the variation of volume and the velocity of bubbles was highlighted. According to the evolution of average mass transfer coefficient, the mass transfer performance in the whole flow process was studied. The results indicated that both the length and velocity of bubble decreased gradually in the flow process due to mass transfer. A linear correlation between the relative velocity (the ratio of average bubble velocity to two-phase superficial velocity) and the relative lost length (the ratio of the lost length to the initial length) was proposed. The increase in overall liquid-phase volumetric mass transfer coefficient (kLa) at higher gas flow rate could be ascribed to the shorter residence time and larger specific surface area. While the increase of kLa at higher liquid flow rate and MEA or [Bmim][BF4] concentration was resulted from intensified mass transfer. An empirical correlation of overall liquid-phase volumetric mass transfer coefficient was proposed taking the gas-phase Reynolds number, liquid-phase Reynolds number and Damkohler number into account.

International audience; The objective of the LORVER project was the construction of fertile Technosols on an industrial brownfield using wastes and byproducts to produce biomass for industrial purposes (hemp as a fiber source and poplar for short rotation coppice). A Life Cycle Assessment (LCA) of the Technosol construction was conducted to highlight the most significant environmental contributions. Three scenarios were compared: a reference scenario (REF) without improvement of the brownfield, a Technosol scenario (LORVER) using industrial byproducts (treated excavated soil, dredging sediments, paper mill sludge, compost and green waste) and a scenario where the brownfield was covered by topsoil (TS). An LCA was performed using SimaPro 8.5, the Ecoinvent v3 database and the ILCD impact indicators. The main contributors to the LORVER scenario that affected air quality and had energy-related impacts were the indirect demand of quicklime due to the use of paper mill sludge, which would have otherwise been spread on fields to save calcic amendments, followed by the transportation of waste from its source to the brownfield site. For the REF and TS scenarios, transportation and organic material spreading caused the most significant impacts. The LORVER scenario was the best or one of the best options for the fertility, carbon and pollution regulation-related impact categories due to the high carbon storage capacity of Technosols and its potential as an alternative solution to waste landfilling. Sensitivity analyses have shown that the LORVER scenario was always the best scenario for the climate change and land-related impacts and that it outperformed alternative scenarios if their required transportation distances exceeded 200 km. This very first LCA of a constructed Technosol made of inert and organic wastes on a brownfield site has proven the merit of this new approach, provided that environmental impacts are evaluated on a case-by-case basis, with the main variability source being the used materials and their alternative management strategies. It has also been demonstrated that these unused soils and materials could provide provisioning, regulation and cultural ecosystem services.

Membrane distillation (MD) is considered an attractive technology for water desalination processes, but the low transmembrane water fluxes, compared to other desalination processes, is however often pointed out as an important disadvantage. This limitation can be tackled through an effective process engineering analysis. Membrane materials performances and process design (including operating conditions) can both generate increased water flux. These two possibilities are explored in this study, in order to better evaluate the interplay between materials and process role. In a first step, the impact of highly permeable and thin dense selfstanding membranes as an alternative to avoid pore wetting is studied. The use of passive process engineering strategies such as Dean vortices to enhance mass and heat transfer is further analyzed. It is shown that a highly permeable dense membrane material offers a potential twofold increase in water flux, when a permeability of 10−5 kg·m−2·s−1·Pa−1 is achieved. Alternatively, Dean vortices (helical hollow fibers) are of interest only when this level of permeance is obtained; a 20% increase in water flux could be achieved, thanks to a decrease of the temperature polarization effect.

High-performance and environment-friendly biomass-based composite films have drawn much attention recently. Here, bio-nanocomposites of TEMPO-oxidized cellulose nanofibrils (TOCNs) reinforced with layered double hydroxides (LDHs) were prepared through an environmentally benign pathway by aqueous dispersion. The results showed that LDHs could be uniformly dispersed in the cellulose nanofibril matrix to form an intercalated nanolayered structure due to good compatibility and the formation of ionic and hydrogen bonds between LDHs with positive charges and TOCNs with negative charges. The TOCN-LDH composite films exhibited high light transmittance, which exceeded 80% with an LDHs content of less than 10%. Moreover, the incorporation of LDHs improved not only the mechanical properties of the cellulose nanofibrils, but also their thermal stability, flame retardancy and hydrophobicity. More specifically, the highest Young's modulus and tensile strength reached 39.3 GPa of TOCN-LDH20 and 358 MPa of TOCN-LDH5, which were 364% and 178% of the neat TOCN film, respectively. The water contact angle and limiting oxygen index of the TOCN-LDH composite film increased from 46° to 103°, and from 25 to 31, respectively, with the LDH content increase from 0 to 20 wt%.

A one pot synthesis of heterostructured bismuth oxide (Bi2O3)/graphitic carbon nitride (g-CN) photocatalysts was developed using Bi(NO3)3 and melamine in 1 M HNO3 as precursors. SEM, TEM and XPS analyses demonstrate that Bi2O3 is closely associated to g-CN, producing contacted interfaces between the two materials. The loading in Bi2O3 was varied from 1.25 to 10 wt% and the highest photocatalytic activity was obtained for the composite containing 2.5% BBN. The Bi2O3 (2.5%)/g-CN material exhibits excellent photocatalytic activity under visible light irradiation for the degradation of RhB as well as a good stability and reusability. Reactive species trapping experiments demonstrated that superoxide O2 − radicals and to a lesser extent holes play a key role in the decomposition of the dye. The high photocatalytic activity of the Bi2O3 (2.5%)/g-CN composite originates from the effective separation of photogenerated charge carriers, which was confirmed by photoluminescence and photocurrent measurements, and from its high specific surface area (26.1 m2/g). The convenient and low cost method developed for the preparation of g-CN-based photocatalysts is of high interest for the synthesis of new heterostructured materials for environmental remediation.

International audience; The cell-specific growth rate (µ) is a critical process parameter for antibody production processes performed by animal cell cultures, as it describes the cell growth and reflects the cell physiological state. When there are changes in these parameters, which are indicated by variations of µ, the synthesis and the quality of antibodies are often affected. Therefore, it is essential to monitor and control the variations of µto assure the antibody production and achieve high product quality. In this study, a novel approach for on-line estimation of µ was developed based on the process analytical technology initiative by using an in situ dielectric spectroscopy. Critical moments, such as significant µ decreases, were successfully detected by this method, in association with changes in cell physiology as well as with an accumulation of nonglycosylated antibodies. Thus, this method was used to perform medium renewals at the appropriate time points, maintaining the values of µ close to its maximum. Using this method, we demonstrated that the physiological state of cells remained stable, the quantity and the glycosylation quality of antibodies were assured at the same time, leading to better process performances compared with the reference feed-harvest cell cultures carried out by using off-line nutrient measurements. K E Y W O R D S antibody glycosylation, cell culture, in situ dielectric spectroscopy, real-time monitoring, specific cell growth rate

CO2 sequestration by reaction with abundant, reactive minerals such as olivine has often been considered. The most straightforward, direct process consists in performing the reaction at high temperature and CO2 pressure, in view to producing silica, magnesium and iron carbonates and recovering the traces of nickel and chromite contained in the feedstock mineral. Most of direct processes were found to have an overall cost far larger than the CO2 removal tax, because of incomplete carbonation and insufficient properties of the reaction products. Similar conclusions could be drawn in a previous investigation with a tubular autoclave. An indirect process has been designed for high conversion of olivine and the production of separate, profitable products e.g. silica, carbonates, nickel salts, so that the overall process could be economically viable: the various steps of the process are described in the paper. Olivine particles (120 μm) can be converted at 81% with a low excess of acid within 3 h at 95°C. The silica quantitatively recovered exhibits a BET area over 400 m2 g-1, allowing valuable applications to be considered. Besides, the low contents of nickel cations could be separated from the magnesium-rich solution by ion exchange with a very high selectivity.

This work is a contribution on thermo-economic analysis of a Liquefied Petroleum Gas (LPG) unit production which is simulated in Aspen HYSYS. The fractional unit of the plant will be studied in order to locate exergy destruction area in the system. The fractional unit contains mainly three sections: heat recovery, rectification columns and cooling section. Also we will determine the exergy for all streams, which will be useful for the thermo-economic analysis. As a result, two thirds of exergy destruction is in deethanizer, depropanizer, debutanizer composing the rectification section. So a detailed exergy analysis is developed for each section.