Novel Ion selective membranes

La capa mediante la técnica de capa se aplicó a modificar membrana de intercambio catiónico (FKB) para mejorar la selectividad de iones monovalentes de la membrana. Cationinc polielectrolito PDADMAC, PSS polielectrolito aniónico y polímero de ion híbrido PSBMA se utiliza para modificar FKB membrana de intercambio catiónico. Las membranas PEM modificado se caracterizaron por espectroscopia UV-Vis y el ángulo de contacto del agua. Rendimiento de la membrana se evaluó mediante la medición de la resistencia eléctrica, lo que limita la densidad de corriente y varios experimentos de difusión. A partir de la medición de la radiación UV-Vis, se obtuvo una relación lineal de la absorbancia en función del número de bicapas lo que significa que hemos depositado con éxito PEM en nuestro sustrato FKB y de manera estequiométrica. La membrana resistencias eléctricas y el ángulo de contacto del agua valores (CA) mostraron una tendencia alterna zig-zag debido a la potencial superficial cambio de capa más externa con cada deposición monocapa. Ángulo de contacto de agua oscilante mostró el comportamiento hidrofobicidad / hidrofilicidad debido al proceso de inversión de carga de superficie en cada deposición monocapa. Una buena propiedad de barrera con PEM se explica lo que puede mejorar la selectividad iónica cuando el número de bicapa es alta. Se encontró que la Ilim de bicapa 6,5 disminuye significativamente cuando se mide a 50 mM KCl entorno sal. La fuerte posibilidad es la exclusión y de capa alta interpenetración Donnan debido a la superficie positivo. Ion experimento transporte de iones únicos y el ion mixto (K + y Li +) por diálisis por difusión se llevó a cabo y se encontró que en bicapa 6,5, disminuye el flujo del K + significativamente a continuación, Li+, que en última instancia, reduce el K+ / Li+ selectividad. El hallazgo importante desde experimento de difusión es que la multicapa catiónico (bicapa 6,5) influyen en el valor de flujo como tal flujo de K+ disminuye más que el Li+, aparentemente selectividad de cualquiera de los compuestos puede ser cambiado por PEM multicapa sobre una membrana de intercambio catiónico. La razón se explica por la combinación de la exclusión de Donnan, radio iónico hidratado de K+ y Li+ y la carga superficial de la membrana

Optical anisotropy, molecular orientations, and internal stresses in thin sulfonated poly(ether ether ketone) films

The thickness, the refractive index, and the optical anisotropy of thin sulfonated poly(ether ether ketone) films, prepared by spin-coating or solvent deposition, have been investigated with spectroscopic ellipsometry. For not too high polymer concentrations (B5 wt%) and not too low spin speeds (C2000 rpm), the thicknesses of the films agree well with the scaling predicted by the model of Meyerhofer, when methanol or ethanol are used as solvent. The films exhibit uniaxial optical anisotropy with a higher in-plane refractive index, indicating a preferred orientation of the polymer chains in this in-plane direction. The radial shear forces that occur during the spin-coating process do not affect the refractive index and the extent of anisotropy. The anisotropy is due to internal stresses within the thin confined polymer film that are associated with the preferred orientations of the polymer chains. The internal stresses are reduced in the presence of a plasticizer, such as water or an organic solvent, and increase to their original value upon removal of such a plasticizer

Theoretical power density from salinity gradients using Reverse Electrodialysis

Reverse electrodialysis (RED) is a technology to generate power from mixing waters with different salinity. The net power density (i.e. power per membrane area) is determined by 1) the membrane potential, 2) the ohmic resistance, 3) the resistance due to changing bulk concentrations, 4) the boundary layer resistance and 5) the power required to pump the feed water. Previous power density estimations often neglected the latter three terms. This paper provides a set of analytical equations to estimate the net power density obtainable from RED stacks with spacers and RED stacks with profiled membranes. With the current technology, the obtained maximum net power density is calculated at 2.7 W/m2. Higher power densities could be obtained by changing the cell design, in particular the membrane resistance and the cell length. Changing these parameters one and two orders of magnitude respectively, the calculated net power density is close to 20 W/m

Salinity gradient energy

There exists a huge potential for the generation of energy from the mixing of saltwater and freshwater. The potential is 2.6 TW, which is more than the global electricity consumption (2.0 TW). Two membrane-based technologies exist to convert this potentially available energy into useful power: pressure-retarded osmosis (PRO) and reverse electrodialysis (RED). In PRO, water is transported through a semipermeable membrane from the less concentrated solution toward the concentrated salt solution to generate power. In RED, salt ions are transported from the concentrated salt solution through ion exchange membranes toward the less concentrated solution to extract the energy. Both technologies were developed in the 1970s and 1980s and both regained interest lately due to recent developments in membrane technology and the need for sustainable energy processes. This chapter describes the potential of salinity gradient energy of both processes in detail, and an overview of the relevant literature on both technologies is presented. Furthermore, it summarizes the recent developments, pilot testing, scale-up, and future expectations of both technologies

Mixed matrix membranes containing MOF's for ethelyne/ethane separation. Part A: Membrane preparation and characterization

Mixed matrix membranes (MMMs) containing three different metal organic frameworks (MOFs) (Cu3BTC2, FeBTC and MIL-53 (Al)) as filler in P84 were prepared and characterized in terms of ethylene/ethane separating ability. SEM, TGA and DSC suggest the absence of non-selective voids in the Cu3BTC2 and FeBTC MMMs. Gas permeation experiments confirmed this, and showed an increase in ethylene/ethane selectivity of 73% to a value of 7.1, while ethylene permeability remained constant at 17×10−18 mol m/(m2 s Pa) with addition of 20 wt% Cu3BTC2. Addition of 20 wt% FeBTC showed a reduced permeability, caused by the formation of a denser intermediate layer, and no significant change in selectivity. Addition of MIL-53 led to increased permeabilities and no change in selectivity, which is probably the result of the formation of non-selective voids or the absence of inherent selectivity of MIL-5