Biodiesel production from jatropha seeds: Solvent extraction and in situ transesterification in a single step

The objective of this study was to investigate solvent extraction and in situ transesterification in a single step to allow direct production of biodiesel from jatropha seeds. Experiments were conducted using milled jatropha seeds, and n-hexane as extracting solvent. The influence of methanol to seed ratio (2:1–6:1), amount of alkali (KOH) catalyst (0.05–0.1 mol/L in methanol), stirring speed (700–900 rpm), temperature (40–60 °C) and reaction time (3–5 h) was examined to define optimum biodiesel yield and biodiesel quality after water washing and drying. When stirring speed, temperature and reaction time were fixed at 700 rpm, 60 °C and 4 h respectively, highest biodiesel yield (80% with a fatty acid methyl ester purity of 99.9%) and optimum biodiesel quality were obtained with a methanol to seed ratio of 6:1 and 0.075 mol/L KOH in methanol. Subsequently, the influence of stirring speed, temperature and reaction time on biodiesel yield and biodiesel quality was studied, by applying the randomized factorial experimental design with ANOVA (F-test at p = 0.05), and using the optimum values previously found for methanol to seed ratio and KOH catalyst level. Most experimental runs conducted at 50 °C resulted to high biodiesel yields, while stirring speed and reaction time did not give significantly effect. The highest biodiesel yield (87% with a fatty acid methyl ester purity of 99.7%) was obtained with a methanol to seed ratio of 6:1, KOH catalyst of 0.075 mol/L in methanol, a stirring speed of 800 rpm, a temperature of 50 °C, and a reaction time of 5 h. The effects of stirring speed, temperature and reaction time on biodiesel quality were not significant. Most of the biodiesel quality obtained in this study conformed to the Indonesian Biodiesel Standard

Mise en réseau des acteurs de l’accueil et de l’intégration des réfugiés

Le sujet de l’accueil et de l’intégration des réfugiés est au coeur du débat public et suscite des réactions ou une réflexion au sein de la société française. Politiques, chercheurs, citoyens,entrepreneurs, employés, beaucoup sont ceux qui se saisissent de la question et tentent d’y apporter une réponse. Malgré l’importance du sujet, une certaine méconnaissance voire une désinformation caractérisent les débats. Dans ce contexte, la Délégation interministérielle chargée de l’accueil et de l’intégration des réfugiés (DIAIR) a été créée pour catalyser les politiques publiques et favoriser le dialogue et la mise en réseau des acteurs. Pour remplir cette dernière mission, le Lab’R, dont la préfiguration constitue ma mission professionnelle, a vu le jour et se définit comme un think tank opérationnel dont le but est de mettre en réseau les acteurs de l’accueil et de l’intégration pour favoriser l’action

Subduction of carbon, nitrogen, and oxygen in the northeast Atlantic

International audienceNortheast Atlantic mode waters (NEAMW) are formed by subduction in a region known to be a strong sink of atmospheric CO2. This study investigates the biological and physical carbon pumps involved in this sink. For that purpose, we estimate the annual transfer of carbon, nitrogen, and oxygen from the surface into the ocean interior through NEAMW subduction. Our estimates are based on a model simulation constrained with data collected during the Programme Océan Multidisciplinaire Méso Echelle (POMME). We found that subduction accounts for a large proportion of carbon export below the mixed layer in the POMME region (38°N-45°N, 16°W-22°W). Fifty percent of labile organic carbon is exported by the biological pump and 50% by subduction; 98% of the total carbon flux below the mixed layer is due to carbon subduction, essentially in the form of dissolved inorganic carbon and of more refractory dissolved organic matter. This is because they are the dominant pools of carbon and are passing through the winter mixed-layer depth gradient that characterizes the region. Our results emphasize that the net export of carbon represents a small fraction of the fluxes of carbon across the mixed layer through the processes of subduction and obduction. Moreover, our results indicate that NEAMW subduction occurs before the spring bloom. This implies that NEAMW is mostly subducted with end-winter characteristics with, in particular, relatively high nutrient content. This reflects a relative inefficiency in nutrient utilization and contrasts with subtropical mode waters, which are subducted during the bloom and are thus relatively poor in nutrients when they are subducted

Modifications of mode water properties by sub-mesoscales in a bio-physical model of the Northeast Atlantic

International audienceNortheast Atlantic mode waters (NEAMW) are formed by subduction in a region which is a strong sink of atmospheric CO2. The mechanisms underlying this sink were thoroughly examined in the frame of the POMME experiment, which covered the 2001 seasonal cycle with particular focus on meso to sub-mesoscales. The biological and physical data collected during POMME were used to initialize, constrain and evaluate a regional, 4.5 km-resolution, bio-physical model simulation of the 2001 seasonal cycle in the region of NEAMW formation. We used this model to examine the contribution of sub-mesoscales on the annual budget of carbon export below the mixed-layer and on NEAMW biogeochemical characteristics. This is done by comparing a high-resolution (eddy) simulation at 4.5 km resolution with a high-diffusivity (non-eddy) simulation where the only change is a stronger eddy diffusivity. We found that the model mixed-layer depth is more stratified and closer to reality in the eddy simulation. This result confirms with observational data the proposed mechanism of restratification of the upper ocean driven by sub-mesoscales. We found that the phytoplankton bloom and the subduction of NEAMW display strong contrasts at the sub-mesoscale. Nevertheless, the mean intensity of the bloom and of the subsequent biological pump are only marginally modified by sub-mesoscales (less than 5%), while the intensity of the physical pump (subduction of carbon) is moderately reduced (−10%) in the non-eddy experiment. Moreover, the biogeochemical and thermodynamical characteristics of NEAMW are substantially affected, with, in particular, a wider range of densities and biogeochemical characteristics biased toward winter conditions in the eddy simulation. These differences ensued essentially from lateral induction across sub-mesoscale filaments, which is found to contribute to subduction before seasonal stratification, i.e. before the effective subduction period

Evaluation des mécanismes d'éviction pour l'accès au logement en Île-de-France: Mise au point d'un outil de cartographie des effets d'éviction

Face à la situation critique du logement à Paris, la DRIHL souhaite disposer d’un outil de cartographie des effets d’éviction des ménages franciliens dans le parc locatif privé. Développé dans un objectif de pérennité, IDEAL (Interface de DEcision pour l’Accessibilité au Logement) s’appuie sur une base de données sans cesse actualisée et permet d’observer, en flux, les zones tendues, la mixité sociale ou encore les effets d’une politique publique comme la loi Pinel

Quelle procédure pour construire une vision commune des problèmes de gestion des eaux urbaines ? L'exemple de la réouverture d'un ru urbain

Colloque avec actes et comité de lecture. internationale.International audienceCette communication s’intéresse principalement aux avantages et inconvénients présentés par un processus de concertation utilisant une procédure de négociation basée sur l’analyse multi-critères. Elle a été testée sur un cas réel en région parisienne : la rivière de la Bièvre, un affluent de la Seine. La procédure de négociation expérimentée par les auteurs a impliqué les gestionnaires de réseau d’assainissement et les gestionnaires de parcs urbains et d’espaces verts de plusieurs collectivités territoriales concernées par le projet. Ce processus a permis aux acteurs de construire des scenarii réalistes, d’expliciter leurs préférences et d’admettre le bien-fondé des préférences des autres acteurs, et de parvenir à la construction d’une conception commune de ce que peut et doit être une rivière « à ciel ouvert