Search

Solid-state batteries are a valuable option for sustainable energy storage. Their performance is strongly dependent on the ionic conductivity of the solid-state electrolyte (SSE). The mechanism of ion conduction in solid polymer electrolytes has been extensively studied in terms of flexibility of the polymer chains and their interactions with mobile cations that hop between conduction sites carrying the charge. The role of the counterion (i.e. anion) interacting with both the polymer and the cation has not been explored in detail. In this study we show however, that the anion can severely impact the conduction as well. The effect of the anion (I−, SCN−, BF4− and PF6−) on the thermal, structural and electrical properties of a solid polymer electrolyte (15C5BA polymer) was investigated. The results clearly show that the nature of the anions can be used as a parameter to actually tune the properties of the polymer electrolyte.

Reverse electrodialysis (RED) is a membrane-based renewable energy technology that can harvest energy from salinity gradients. The anticipated feed streams are natural river and seawater, both of which contain not only monovalent ions but also divalent ions. However, RED using feed streams containing divalent ions experiences lower power densities because of both uphill transport and increased membrane resistance. In this study, we investigate the effects of divalent cations (Mg(2+) and Ca(2+)) on RED and demonstrate the mitigation of those effects using both novel and existing commercial cation exchange membranes (CEMs). Monovalent-selective Neosepta CMS is known to block divalent cations transport and can therefore mitigate reductions in stack voltage. The new multivalent-permeable Fuji T1 is able to transport divalent cations without a major increase in resistance. Both strategies significantly improve power densities compared to standard-grade CEMs when performing RED using streams containing divalent cations.

In this work, the decisive role of rigidity, orientation, and order in the smectic liquid crystalline network on the anisotropic proton and adsorbent properties is reported. The rigidity in the hydrogen-bonded polymer network has been altered by changing the cross-link density, the order by using different mesophases (smectic, nematic, and isotropic phases), whereas the orientation of the mesogens was controlled by alignment layers. Adding more cross-linkers improved the integrity of the polymer films. For the proton conduction, an optimum was found in the amount of cross-linker and the smectic organization results in the highest anhydrous proton conduction. The polymer films show anisotropic proton conductivity with a 54 times higher conductivity in the direction perpendicular to the molecular director. After a base treatment of the smectic liquid crystalline network, a nanoporous polymer film is obtained that also shows anisotropic adsorption of dye molecules and again straight smectic pores are favored over disordered pores in nematic and isotropic networks. The highly cross-linked films show size-selective adsorption of dyes. Low cross-linked materials do not show this difference due to swelling, which decreases the order and creates openings in the two-dimensional polymer layers. The latter is, however, beneficial for fast adsorption kinetics.

Potassium is an important nutrient used in fertilizers but is not always naturally available We investigated the properties of polymer inclusion membranes (PIM) regarding their selective recovery of K+ over competitive ions typically present in urine (Na+ and NH4 +). The greatest flux was observed when the ratio of mass 2-nitrophenyl octyl ether (2-NPOE) used as plasticizer to cellulose triacetate (CTA) used as polymer was 0.25. The highest flux was achieved with a content of 24.8 wt % of dicyclohexan-18-crown-6 (DCH18C6) used as carrier, although the highest selectivity was observed with a content of 14.0 wt % of DCH18C6. We also studied whether the transport mechanism occurring in our system was based on co-transport of a counter-ion or ion exchange. Two different receiving phases (ultrapure water and 100 mM HCl) were tested. Results on transport mechanisms suggest that co-transport of cations and anions is taking place across our PIMs. The membrane deteriorated and lost its properties when the receiving phase was acidic; we suggested that this was due to hydrolysis of CTA. The greatest flux and selectivity were observed in ultrapure water as receiving phase.

The present invention pertains to a process for the separation of methanol and water from non-condensables wherein a feed stream comprising methanol, water and non-condensables is subjected to a membrane separation step at a temperature of at least 150°C and a pressure of at least 1 bar (100 kPa) thereby separating the mixture into a permeate being enriched in methanol and water as compared to the feed stream and a retentate being leaner in methanol and water as compared to the feed stream, characterized in that the membrane separation step is carried out using a membrane comprising a separating layer of sulfonated poly ether.

Composite ultrafiltration membranes were fabricated by coating a thin film of self-assembling polystyrene-block-poly(ethylene oxide) (PS-b-PEO) block copolymers and poly(acrylic acid) homopolymers on top of a support membrane. Block copolymers self-assembled into a nanostructure where the minority component forms cylinders, whereas homopolymers reside in the core of the cylinders. Selective removal of the homopolymers led to the formation of pores. The morphology of the polymer layer was controlled by varying the content of homopolymers or polymer concentration of the coating solution, which led to membranes with different molecular weight cutoffs (MWCOs) and permeabilities. Uniform pores were obtained using low homopolymer contents, whereas high homopolymer contents caused macrophase separation and resulted in large polydisperse pores or craters at the surface. The thickness of the block copolymer film also influenced the structure and performance of the membranes, where a thicker film results in a strong decrease in permeability but a lower MWCO.

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 (≤5 wt%) and not too low spin speeds (≥2000 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.

Kitty Nijmeijer (Universiteit Twente) vraagt de mensen in de collegezaal te kiezen tussen een glas helder mineraalwater en een glas met bruin water uit de grachten van Amsterdam. Dat is geen moeilijke keuze, maar Kitty weet zeker dat het publiek na het college van gedachten is veranderd. Deze week in Universiteit van Nederland: Chemicus prof. dr. ir. Kitty Nijmeijer! Prof. dr. ir. Kitty Nijmeijer is hoogleraar Membraantechnologie aan de Universiteit Twente. Professor Nijmeijer doet revolutionair onderzoek naar het opwekken van energie via een membraan, een soort supersonische filter. In 2014 bracht professor Nijmeijer haar onderzoek in de praktijk door de eerste blauwe energiecentrale aan de Afsluitdijk te openen.

Als je zout en zoet water mengt, dan ontstaat er energie. Maar het simpelweg door elkaar gooien is niet genoeg, als je dat soms denkt. Je moet de energie zien op te vangen met behulp van membranen. Kitty Nijmeijer (Universiteit Twente) legt het uit aan de hand van vrolijke balletjes en plastic velletjes, en laat ondertussen onbedoeld je scheikundeleraar van de middelbare school verbleken.

This article provides an up-to-date perspective on the use of anion-exchange membranes in fuel cells, electrolysers, redox flow batteries, reverse electrodialysis cells, and bioelectrochemical systems (e.g. microbial fuel cells). The aim is to highlight key concepts, misconceptions, the current state-of-the-art, technological and scientific limitations, and the future challenges (research priorities) related to the use of anion-exchange membranes in these energy technologies. All the references that the authors deemed relevant, and were available on the web by the manuscript submission date (30th April 2014), are included.

Carbon hollow fiber membranes have been prepared by pyrolysis of a P84/S-PEEK blend. Proximate analysis of the precursor was performed using thermogravimetry (TGA), and a carbon yield of approximately 40 can be obtained. This study aimed at understanding the influence of pyrolysis parametersend temperature, quenching effect, and soaking timeon the membrane properties. Permeation experiments were performed with N 2, He, and CO 2. Scanning electron microscopy (SEM) has been done for all carbon hollow fibers. The highest permeances were obtained for the membrane submitted to an end temperature of 750 C and the highest ideal selectivities for an end temperature of 700 C. In both cases, the membranes were quenched to room temperature.