Query: Membranes for VRB

title: An overview of amphoteric ion exchange membranes for vanadium redox flow batteries
abstract: Vanadium redox flow battery (VRB) as the most promising large scale electrical energy storage units, has attracted extensive attention. Amphoteric ion exchange membrane (AIEM) as the core part of VRB, separates electrolyte on both sides of electrolytic tank and conducts H+ The AIEM with cation and anion groups possesses excellent performances, such as high ion conductivity (s) low vanadium ion permeability (PVn+ relative stability and low cost. However, the performance of AIEM directly depends on the chemical structure of polymers. In addition to ensuring foundational physical performance, ion selectivity of AIEM is significant since the crossover of vanadium ion with various valences may reduce the battery capacity. In this paper, AIEMs for VRB and their chemical structures as well as synthesis approaches to realize all kinds of high performing AIEMs are reviewed. The current trend and future direction of prospective materials for the VRB separators are documented in detail as well.

title: Dynamic model based membrane permeability estimation for online SOC imbalances monitoring of vanadium redox flow batteries
abstract: A model based approach is developed to determine the membrane permeability properties including vanadium ion crossover and water transfer behaviour for the vanadium redox flow battery (VRB) system. The permeability of vanadium ions and water transfer coefficients are estimated through nonlinear optimisation with measured negative and positive half cell potentials. Experimental studies were conducted to test two different membranes as examples to illustrate the effectiveness of the proposed approach. This method can significantly simplify the conventional approach to characterising the membrane permeability property. The results are useful for online prediction of the battery system capacity decay and for scheduling regular maintenance such as electrolyte rebalancing to restore capacity.

title: Amphoteric Nafion membrane with tunable cationic and anionic ratios for vanadium redox flow battery prepared via atom transfer radical polymerization
abstract: Nafion is currently the most stable ion exchange membrane for vanadium redox flow battery (VRB) In order to decrease the high vanadium permeability of Nafion while still keeping its high ionic conductivity and stability, in this study, solution atom transfer radical polymerization (ATRP) method is used with Nafion as initiator to prepare amphoteric Nafion membrane with tunable cationic and anionic ratios. Polymers of [2 (methacryloyloxy)ethyl] trimethylammonium chloride (METAC) and sodium 4 styrenesulfonate (NaSS) are chosen as cationic and anionic monomers, respectively. FT IR (Fourier transform infrared) and 1H NMR (nuclear magnetic resonance) tests prove that the METAC and NaSS have been successfully bonded on the Nafion molecules. The solution casted amphoteric Nafion membrane M 1:1 has shown the highest ion selectivity among all the grafted Nafion membranes. The VRB with M 1:1 membrane has shown the highest average energy efficiency of 83.9% at current density of 40 80 mA cm 2, which is 4.2% higher than that of Nafion 212 (79.7% One hundred cycles dynamic charge discharge test proves that the M 1:1 membrane possesses enough stability and good discharge capacity retention ability. On line self discharge test further proves that the M 1:1 membrane has lower vanadium ions permeation than that of Nafion 212 membrane. All the results prove that ATRP is an effective method for preparation of novel amphoteric materials for VRB application.

title: Bi functional side chain architecture tuned amphoteric ion exchange membranes for high performance vanadium redox flow batteries
abstract: The blended amphoteric membranes possessed a reducing cation exchange capacity with increasing the anion exchange capacity. Bi functional side chain type polymers are conducive to have both high cation exchange capacity and high anion exchange capacity at the same time, and further enhance ion conductivity of amphoteric ion exchange membranes (AIEMs) Herein, novel side chain type AIEMs are prepared via ring opening metathesis polymerization of norbornene possessing the advantages of yielding easily modified molecular architectures, simple and controllable polymerization, and producing the membranes with high chemical stability. To avoid the occurrence of excess water swelling arising from the increased zwitterionic groups, hydrophobic spacers (alkyl chain (CH2)6 were introduced to be situated between the aromatic main chain and ionic groups. This unique structure favors ion clusters to be aggregated and thus forms highly ordered water channels so that the protons can be efficiently transported along the center of channels and possess excellent proton conductivity. In addition, the ion crosslinking interactions enhance the mechanical stability of AIEMs. The resultant AIEM (1/2) exhibits a higher ion conductivity of 7.58 x 10 2 S cm 1 and vanadium ion permeability of 0.21 x 10 9 cm2 s 1 at room temperature. Based on these good properties, the vanadium redox flow batteries (VRBs) with prepared membranes and Nafion 212 were tested. The energy efficiency (EE) of VRBs with AIEM (1/2) still reaches 84.76% at the current density of 160 mA cm 2, which is better than that with Nafion 212 (76.26% Moreover, the EE of VRBs with AIEM (1/2) is 82.11% after 200 cycles, indicating that the prepared membranes possess a good stability.

title: Numerical modeling of in plane thermal conductivity measurement methods based on a suspended membrane setup
abstract: A numerical modeling study based on 3D finite element method (FEM) simulation and 1D analytical solutions has been carried out to evaluate the capabilities of two ac methods for measuring in plane thermal conductivity of thin film deposited on the back of a suspended SiNx membrane setup. Two parallel metal strips are present on the top of the dielectric membrane. One strip (S1) serves as both heater and thermometer, while another one (S2) acts as thermometer only. For a modified phase shift (MPS) method, it is crucial to extract the in plane thermal diffusivity from the phase shift of the temperature oscillation on S2. It was found that the frequency window for carrying out the data fitting became narrower as the in plane thermal diffusivity of the composite membrane \alpha_{\parallel ,C} increased, primarily due to the failure of the semi infinite width assumption in the low frequency region. To ensure the validity of the method, the upper limit of \alpha_{\parallel ,C} should not exceed ~1.8$ \times $10 5 m2 s 1 for the specific membrane dimension under consideration (1$\times $1 mm2) On the other hand, inspired by a modified Angstrom method proposed by Zhu recently, we suggest a new data reduction methodology which takes advantage of the phase shift on both S1 and S2 as well as the amplitude on S1. Based on the simulation results, it is expected that the non ideality associated with the three observables may be at least partially cancelled out.Therefore, the frequency window selection for carrying out the data fitting is not sensitive to the magnitude of \alpha_{\parallel ,C} For typical specimen films whose in plane thermal conductivity ranges from 0.84 W m 1 K 1 to 50 W m 1 K 1, the method proposed here yields a theoretical measurement uncertainty of less than 5%

title: Electrochemical removal of amphoteric ions
abstract: Water treatment is required for a sustainable potable water supply and can be leveraged to harvest valuable elements. Crucial to these processes is the removal of charge pH dependent species from polluted water, such as boron, ammonia, and phosphate. These species can be challenging for conventional technologies. Currently, boron removal requires several reverse osmosis stages, combined with dosing a caustic agent. Capacitive deionization (CDI) promises to enable effective removal of such species without chemical additives but requires a deep understanding of the coupled interplay of pH dynamics, ion electrosorption, and transport phenomena. Here, we provide a detailed theory tackling this topic and show both theoretically and experimentally highly counterintuitive design rules governing pH dependent ion removal by CDI. Several harmful or valuable ionic species present in seawater, brackish water, and wastewater are amphoteric, weak acids or weak bases, and, thus, their properties depend on local water pH. Effective removal of these species can be challenging for conventional membrane technologies, necessitating chemical dosing of the feedwater to adjust pH. A prominent example is boron, which is considered toxic in high concentrations and often requires additional membrane passes to remove during seawater desalination. Capacitive deionization (CDI) is an emerging membraneless technique for water treatment and desalination, based on electrosorption of salt ions into charging microporous electrodes. CDI cells show strong internally generated pH variations during operation, and, thus, CDI can potentially remove pH dependent species without chemical dosing. However, development of this technique is inhibited by the complexities inherent to the coupling of pH dynamics and ion properties in a charging CDI cell. Here, we present a theoretical framework predicting the electrosorption of pH dependent species in flow through electrode CDI cells. We demonstrate that such a model enables insight into factors affecting species electrosorption and conclude that important design rules for such systems are highly counterintuitive. For example, we show both theoretically and experimentally that for boron removal, the anode should be placed upstream and the cathode downstream, an electrode order that runs counter to the accepted wisdom in the CDI field. Overall, we show that to achieve target separations relying on coupled, complex phenomena, such as in the removal of amphoteric species, a theoretical CDI model is essential.

title: Association between Urinary Metabolites and the Exposure of Intensive Care Newborns to Plasticizers of Medical Devices Used for Their Care Management
abstract: Care management of newborns in the neonatal intensive care unit (NICU) requires numerous PVC (PolyVinyl Chloride) medical devices (MD) containing plasticizers that can migrate and contaminate the patient. We measured the magnitude of neonates' exposure to plasticizers (di ethylhexylphthalate (DEHP) and alternatives) in relation to urinary concentrations of their metabolites. Plasticizers' exposure was evaluated (1) by calculating the amounts of plasticizers prone to be released from each MD used for care management, and (2) by measuring the patients' urinary levels of each plasticizers' metabolites. 104 neonates were enrolled. They were exposed to di isononylphthalate (DINP) especially via transfusion and infusion MD, and to DEHP via ECMO (Extra Corporeal Membrane Oxygenation) and respiratory assistance MD. Mean exposure doses exceeded the derived no effect level of DINP and DEHP by a 10 fold and a 1000 fold factor. No PVC MD were plasticized with di isononylcyclohexane 1,2 dicarboxylate (DINCH) High urinary concentrations of DEHP metabolites were directly correlated with DEHP exposure through ECMO MD. Urinary concentrations of DINP metabolites in transfused patients were also high. DINCH metabolites were found in urine, suggesting another route of exposure. Neonates in NICU are considerably exposed to plasticizers, with magnitudes varying with the type of MD used. The high exposure to DEHP and DINP leads to a risk of their metabolites' toxicity.

title: Nebulized Colistin in Ventilator Associated Pneumonia and Tracheobronchitis: Historical Background, Pharmacokinetics and Perspectives
abstract: Clinical evidence suggests that nebulized colistimethate sodium (CMS) has benefits for treating lower respiratory tract infections caused by multidrug resistant Gram negative bacteria (GNB) Colistin is positively charged, while CMS is negatively charged, and both have a high molecular mass and are hydrophilic. These physico chemical characteristics impair crossing of the alveolo capillary membrane but enable the disruption of the bacterial wall of GNB and the aggregation of the circulating lipopolysaccharide. Intravenous CMS is rapidly cleared by glomerular filtration and tubular excretion, and 20 25% is spontaneously hydrolyzed to colistin. Urine colistin is substantially reabsorbed by tubular cells and eliminated by biliary excretion. Colistin is a concentration dependent antibiotic with post antibiotic and inoculum effects. As CMS conversion to colistin is slower than its renal clearance, intravenous administration can lead to low plasma and lung colistin concentrations that risk treatment failure. Following nebulization of high doses, colistin (200,000 international units/24h) lung tissue concentrations are five times minimum inhibitory concentration (MIC) of GNB in regions with multiple foci of bronchopneumonia and in the range of MIC breakpoints in regions with confluent pneumonia. Future research should include: (1) experimental studies using lung microdialysis to assess the PK/PD in the interstitial fluid of the lung following nebulization of high doses of colistin; (2) superiority multicenter randomized controlled trials comparing nebulized and intravenous CMS in patients with pandrug resistant GNB ventilator associated pneumonia and ventilator associated tracheobronchitis; (3) non inferiority multicenter randomized controlled trials comparing nebulized CMS to intravenous new cephalosporines/ss lactamase inhibitors in patients with extensive drug resistant GNB ventilator associated pneumonia and ventilator associated tracheobronchitis.

title: Correction to: Relation of anatomy with function following the surgical treatment of idiopathic epiretinal membrane: a multicenter retrospective study
abstract: A Correction to this paper has been published: https:/doi.org/10.1007/s00417 021 05131 1

title: Two dimensional MoS2 nanosheets constructing highly ion selective composite membrane for vanadium redox flow battery
abstract: A novel double layer composite membrane with a MoS2 rich layer and a polymer rich layer is prepared by the method of one step slow solvent evaporation for vanadium redox flow batteries. The composite membrane is composed of MoS2 nanosheets as protecting layer, providing the membrane with lower VO2+ permeability and excellent chemical stability, and sulfonated modified PBI as substrate, providing high proton conductivity. The introduction of MoS2 nanosheets greatly reduces the area resistance of the PBI PS/MoS2 membrane (0.42 O cm2) which is comparable to that of Nafion 212 (0.41 O cm2) The cell equipped with PBI PS/MoS2 membrane presents improved coulombic efficiencies and energy efficiencies. At 200 mA cm 2, a high EE of about 80% is achieved. The cell maintains stable performances for nearly 800 cycles, showing impressive durability. The cell also shows a self discharge rate of as low as 0.0021 V h 1. The MoS2 nanosheets layer based composite membrane is promising for VRBs.