Phase Equilibrium Feasibility Studies of Free Fatty Acids Extraction from Palm Oil Using Supercritical Carbon Dioxide

This work investigates the modeling of saturated fatty acids from palm oil using co-solvent modified supercritical carbon dioxide (SC-CO2). The objective of this work is the assessment of the feasibility studies of phase equilibrium mutual solubility process utilizing supercritical carbon dioxide. The knowledge of the phase equilibrium is one of the most important factors to study the design of extraction processes controlled by the equilibrium. The applied pressure was ranging from 60 to 180 bars and the extraction temperatures were 313.15 and 353.15 K. A thermodynamic model based on the Universal Functional Activity Coefficient (UNIFAC) used to predict the activity coefficients' expression for the system carbon dioxide / fatty acid. The parameters such as adsorption, diffusion, mass transfer coefficient, solubility, and desorption were determined using mass transfer modeling. Keywords: Supercritical Carbon Dioxide; Free Fatty Acids; UNIFAC; Activity Coefficient; Mass Transfer Modeling

Pore size distribution and supercritical hydrogen adsorption in activated carbon fibers

Pore size distributions (PSD) and supercritical H_2 isotherms have been measured for two activated carbon fiber (ACF) samples. The surface area and the PSD both depend on the degree of activation to which the ACF has been exposed. The low-surface-area ACF has a narrow PSD centered at 0.5 nm, while the high-surface-area ACF has a broad distribution of pore widths between 0.5 and 2 nm. The H_2 adsorption enthalpy in the zero-coverage limit depends on the relative abundance of the smallest pores relative to the larger pores. Measurements of the H_2 isosteric adsorption enthalpy indicate the presence of energy heterogeneity in both ACF samples. Additional measurements on a microporous, coconut-derived activated carbon are presented for reference

LiSc(BH_4)_4 as a Hydrogen Storage Material: Multinuclear High-Resolution Solid-State NMR and First-Principles Density Functional Theory Studies

A lithium salt of anionic scandium tetraborohydride complex, LiSc(BH_4)_4, was studied both experimentally and theoretically as a potential hydrogen storage medium. Ball milling mixtures of LiBH_4 and ScCl_3 produced LiCl and a unique crystalline hydride, which has been unequivocally identified via multinuclear solid-state nuclear magnetic resonance (NMR) to be LiSc(BH_4)_4. Under the present reaction conditions, there was no evidence for the formation of binary Sc(BH_4)_3. These observations are in agreement with our first-principles calculations of the relative stabilities of these phases. A tetragonal structure in space group I (#82) is predicted to be the lowest energy state for LiSc(BH_4)_4, which does not correspond to structures obtained to date on the crystalline ternary borohydride phases made by ball milling. Perhaps reaction conditions are resulting in formation of other polymorphs, which should be investigated in future studies via neutron scattering on deuterides. Hydrogen desorption while heating these Li−Sc−B−H materials up to 400 °C yielded only amorphous phases (besides the virtually unchanged LiCl) that were determined by NMR to be primarily ScB_2 and [B_(12)H_(12)]^(−2) anion containing (e.g., Li_2B_(12)H_(12)) along with residual LiBH_4. Reaction of a desorbed LiSc(BH_4)_4 + 4LiCl mixture (from 4LiBH_4/ScCl_3 sample) with hydrogen gas at 70 bar resulted only in an increase in the contents of Li_2B_(12)H_(12) and LiBH_4. Full reversibility to reform the LiSc(BH_4)_4 was not found. Overall, the Li−Sc−B−H system is not a favorable candidate for hydrogen storage applications

Argania spinosa as potential oilseed resource for the future: genotype impact in oil content and fatty acids composition

Argania spinosa (L.) is one of the most economically and culturally important indigenous species in Morocco. Its seeds contain a vegetable oil, internationally known as argan oil, which is widely used in edible, cosmetic and pharmaceutical sectors. The aim of this study was to assess the levels of variation in oil content and fatty acid composition of eighteen trees to identify genotypes with desirable traits in terms of oil quantity, quality and industrial utilization. Oil yield of eighteen genotypes was determined after mechanical pressing, and fatty acid methyl ester analysis was carried out using gas liquid chromatography. Obtained results show that oil yields ranged between 37.2 to 43.8% and major fatty acids in the extracted oil were oleic (47.15%), followed by linoleic (31.57%), palmitic (14.24%) and stearic (5.8%) acid. Fatty acids composition was significantly different among genotypes tested. Significant correlations, both positive and negative were located between some fatty acids. The high variability observed between genotypes represents a very promising base to develop a new argan variety with high oil quality

Disk-Graph Probabilistic Roadmap: Biased Distance Sampling for Path Planning in a Partially Unknown Environment

International audienceIn this paper, we propose a new sampling-based path planning approach, focusing on the challenges linked to autonomous exploration. Our method relies on the definition of a disk graph of free-space bubbles, from which we derive a biased sampling function that expands the graph towards known free space for maximal navigability and frontiers discovery. The proposed method demonstrates an exploratory behavior similar to Rapidly-exploring Random Trees, while retaining the connectivity and flexibility of a graph-based planner. We demonstrate the interest of our method by first comparing its path planning capabilities against state-of-theart approaches, before discussing exploration-specific aspects, namely replanning capabilities and incremental construction of the graph. A simple frontiers-driven exploration controller derived from our planning method is also demonstrated using the Pioneer platform

Selective mode excitation in SCM-OCDMA

A six-channel 2.4GHz subcarrier multiplexing - optical code division multiple access (SCM-OCDMA) system in conjunction with the selective excitation of LP01 and LP02 modes is presented for a multimode fiber Local Area Network. Simulation results demonstrate that mode selectivity increases the bandwidth-distance product and improves the BER performance of the channel

Composition en antioxydants et activité coagulante des artichauts sauvage et cultivé au Maroc (Cynara cardunculus L.)

Natural plant extracts are sustainable alternatives to chemical food additives with less side effects. Wild and cultivated artichoke bracts (cynara cardunculus L.) were evaluated for their bioactive content and scavenging activity on two stages (bracts stage) I and (full bloom stage) II. Head flowers were collected from the second stage and analyzed for their coagulating properties. Phenolic compounds, flavonoids total content in bracts extracts of wild artichoke significantly exceeded those of the cultivated plant; a decrease of these compounds was noted from stage I to stage II for both plants. Flowers Enzymatic extract of both plants exhibited a reduced clotting time and a lower proteolytic activity. Indeed, 280 μg tyr / ml was measured for microbial rennet, 90 μg tyr / ml for the wild artichoke flower extract and 85 μg tyr / ml for the cultivated artichoke flower. This study revealed the potential interest of valorization of artichoke different parts commonly considered as dietary waste in different food and health applications.Les extraits naturels de plantes sont des alternatives durables aux additifs alimentaires chimiques avec moins d'effets secondaires. Les bractées d'artichaut sauvage et cultivé (cynara cardunculus L.) ont été évaluées pour leur teneur en composés bioactifs et leur activité de piégeage sur deux stades (stade des bractées) I et (stade de pleine floraison) II. Les fleurs des capitules d’artichaut ont été récoltées en pleine floraison et analysées pour leurs propriétés coagulantes. Les résultats ont démontré que les composés phénoliques, les teneurs en flavonoïdes dans les extraits de bractées d'artichaut sauvage dépassaient significativement celles de la plante cultivée ; une diminution de ces composés a été notée du stade I au stade II pour les deux plantes. L'extrait enzymatique des fleurs des deux plantes a présenté un temps de coagulation réduit et une activité protéolytique plus faible. En effet, 280 μg tyr/ml a été mesuré pour la présure microbienne, 90 μg tyr/ml pour l'extrait de fleur d'artichaut sauvage et 85 μg tyr/ml pour la fleur d'artichaut cultivée. Cette étude a révélé l'intérêt potentiel de la valorisation des différentes parties de l'artichaut communément considérées comme des déchets alimentaires dans différentes applications alimentaires et de santé