Sel alimentaire | EPFL Graph Search

vignette|Sel alimentaire blanc. Le sel de table, sel alimentaire ou sel de cuisine, est composé essentiellement de chlorure de sodium. Il se présente sous différentes formes : gros sel (ou sel gros), sel fin, fleur de sel. Histoire Histoire du sel Le sel est connu depuis la Préhistoire (voir une des plus anciennes villes préhistoriques d'Europe Solnitsata) pour ses caractéristiques d'assaisonnement et de conservation des aliments. Il était extrait de mines généralement très enfouies dans le sol (mines de roches évaporitiques telle que la halite), ou plus facilement de sources salées ou de la mer (saliculture). Les tessons de briquetages, céramiques utilitaires dans l'extraction de sel (marmites où l'on faisait bouillir la saumure sur des fours à feux de bois et bâtonnets d'argile cuite dont l'assemblage permettait une partie de l'évaporation de cette saumure) sont fréquemment retrouvés jusqu'à l'âge du fer, période qui voit l'apparition d'outillages plus robustes et de pl

Determining The Potential Of Salinity Gradient Energy Source Using An Exergy Analysis

Arash Emdadi

Mixing of fresh (river) water and salty water (seawater or saline brine) in a control fashion would produces an electrical energy known as salinity gradient energy (SGE). Two main conversion technologies of SGE are membrane-based processes; pressure retarded osmosis (PRO) and reverse electrodialysis (RED). In PRO, semipermeable membranes placed between the two streams of solutions allow the transport of water from low-pressure diluted solution to high-pressure concentrated solution. RED requires two alternating semipermeable membranes that allow the diffusion of the ions but not the flow of H2O. Lifetime and power density of the semipermeable membrane are two main factors affecting on deployment of PRO and RED. Semipermeable membranes with lifetime greater than 10 years and power density higher than 5 W/m(2) would lead to faster development of this conversion technology. An exergy analysis of an SGE system of sea-river can be applied to calculate the maximum potential power for electricity generation. Seawater is taken as reference environment (global dead state) for calculating the exergy of water since the seawater is the final reservoir. Once the fresh water is mixed with water of the sea or lake it becomes unuseful for human, agricultural or industrial uses loses all its exergy. Aqueous sodium chloride solution model is used in this study to calculate the thermodynamic properties of seawater. This model does not consider seawater as an ideal model and provides accurate thermodynamics properties of sodium chloride solution. As a case study, exergy calculation of Iran's Urmia Lake- GadarChay River system. The chemical exergy analysis considers sodium chloride (NaCl) as main salt in the water of Lake Urmia. The sodium chloride concentration is more than 200 g/L in recent years. Based on the exergy results the potential power of this system is 329 MW. This results indicates a high potential for constructing power plant for salinity gradient energy conversion.

Amer Soc Mechanical Engineers2016

Structural and Dynamical Properties of Potassium Dodecahydro-monocarba-closo-dodecaborate: KCB11H12

Mirjana Dimitrievska, Wei Zhou

MCB11H12 (M: Li, Na) dodecahydro-monocarba-closo-dodecaborate salt compounds are known to have stellar superionic Li+ and Na+ conductivities in their high-temperature disordered phases, making them potentially appealing electrolytes in all-solid-state batteries. Nonetheless, it is of keen interest to search for other related materials with similar conductivities while at the same time exhibiting even lower (more device-relevant) disordering temperatures, a key challenge for this class of materials. With this in mind, the unknown structural and dynamical properties of the heavier KCB11H12 congener were investigated in detail by X-ray powder diffraction, differential scanning calorimetry, neutron vibrational spectroscopy, nuclear magnetic resonance, quasielastic neutron scattering, and AC impedance measurements. This salt indeed undergoes an entropy-driven, reversible, order-disorder transformation and with a lower onset temperature (348 K upon heating and 340 K upon cooling) in comparison to the lighter LiCB11H12 and NaCB11H12 analogues. The K+ cations in both the low-T ordered monoclinic (P2(1)/c) and high-T disordered cubic (Fm (3) over barm) structures occupy octahedral interstices formed by CB11H12- anions. In the low-T structure, the anions orient themselves so as to avoid close proximity between their highly electropositive C-H vertices and the neighboring K+ cations. In the high-T structure, the anions are orientationally disordered, although to best avoid the K+ cations, the anions likely orient themselves so that their C-H axes are aligned in one of eight possible directions along the body diagonals of the cubic unit cell. Across the transition, anion reorientational jump rates change from 6.2 x 10(6) s(-1) in the low-T phase (332 K) to 2.6 x 10(10) s(-1) in the high-T phase (341 K). In tandem, K+ conductivity increases by about 30-fold across the transition, yielding a high-T phase value of 3.2 x 10(-4 )S cm(-1 )at 361 K. However, this is still about 1 to 2 orders of magnitude lower than that observed for LiCB(11)H(12 )and NaCB11H12, suggesting that the relatively larger K+ cation is much more sterically hindered than Li+ and Na+ from diffusing through the anion lattice via the network of smaller interstitial sites.

AMER CHEMICAL SOC2020