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Recent Advances in Anion Exchange Membranes for Fuel Cell Applications
Published in Anandhan Srinivasan, Selvakumar Murugesan, Arunjunai Raj Mahendran, Progress in Polymer Research for Biomedical, Energy and Specialty Applications, 2023
Vijayalekshmi Vijayakumar, Sang Yong Nam
The anion exchange membranes with high ionic conductivity and long-term durability remain a challenge in the development of the anion exchange membranes. Conductivity is proportional to the mobility coefficient and concentration of charge carriers. The lower mobility coefficient of OH− ions (only half) than H+ ions in infinitely dilute solutions at room temperature leads to low hydroxide ion conductivity. Increasing the concentration of anion exchange group (ion exchange capacity) is the most straightforward method to improve hydroxide ion conductivity however, maintaining dimensional as well as alkaline stability is a challenge [12]. In view of that, a variety of polymeric membranes with advanced architectures have been reported as great potential for fuel cell applications.
Desalination
Published in P.K. Tewari, Advanced Water Technologies, 2020
Electrodialysis uses membranes that are selectively permeable to ions, based on their charge. Two types of selective membranes are used, those for cation exchange and anion exchange. Membranes that permeate cations are called cation-exchange membranes. Membranes that permeate anions are known as anion-exchange membranes. These membranes are placed alternately, with flow channels between them. Electrodes are placed on each side. An electric current is applied to the ED unit. Due to the electric field, the respective membranes allow the cations and anions to pass through. The electrodes draw their counter-ions through the membranes, so that these are removed from the water, thus giving purified water.
Prospects on utilization of biopolymer materials for ion exchange membranes in fuel cells
Published in Green Chemistry Letters and Reviews, 2022
Angelo Jacob Samaniego, Richard Espiritu
Anion exchange membrane fuel cells (AEMFC) operate in a similar principle to PEMFC but produce OH- at the cathode through oxygen gas reduction and transport these through the anion exchange membrane (AEM) towards the anode (Figure 1(b)). Apart from this, AEMFC have the distinct advantage of having a faster oxygen reduction reaction than PEMFC which brings lower activation losses in effect permitting the use of cheaper non-noble metal catalysts for both electrodes (17–19). The possibility of cheaper fabrication costs has spurred research into numerous chemistries of AEM, employing similar strategies to PEM synthesis such as through formation of hydrophilic–hydrophobic phase separation for improved ionic conductivity, crosslinking of ionic clusters, and development of interpenetrating functionalized polymer networks (20). With all these considerations, researchers struggle to create the ideal IEM exhibiting high ionic conductivity and low fuel permeability while maintaining high durability and stability, all at an economical production cost (2, 21, 22).
Selective electrodialysis for simultaneous but separate phosphate and ammonium recovery
Published in Environmental Technology, 2021
Katie Charlotte Kedwell, Mads Koustrup Jørgensen, Cejna Anna Quist-Jensen, Tien Duc Pham, Bart Van der Bruggen, Morten Lykkegaard Christensen
A new method to concentrate both phosphorus and ammonium is selectrodialysis. Seletrodialysis utilizes traditional electrodialysis, in which ions move across ion-permeable membranes via an electrical charge, and combines this with a monovalent anion exchange membrane (MVA) [25]. This enables the separation of monovalent and divalent ions. Therefore, useful diluate charged components can be separated from contaminants or undesirable components if their charge valences are different [26–29]. Selectrodialysis can be used to separate phosphate and ammonium from digester supernatant. Previous studies have recovered phosphate, or ammonia, or both, in the same concentrate using MVA and CEM membranes. However, concentrating each in separate concentrate streams (i.e. anion concentrate and cation concentrate) has not been widely investigated [23,29,30].
Medium-chain-length poly-3-hydroxyalkanoates-carbon nanotubes composite as proton exchange membrane in microbial fuel cell
Published in Chemical Engineering Communications, 2019
Hindatu Yusuf, M. Suffian M. Annuar, Syed Mohammad Daniel Syed Mohamed, Ramesh Subramaniam
The application of natural rubber latex in MFC was compared with that of cation ion-exchange membrane (CEM) and anion exchange membrane (AEM). The startup time of the CEM was shorter than natural rubber at the initial period of MFC operation. However, the rubber material performance was enhanced with time and superseded that of CEM and AEM during long-term MFC operation. The superior performance was attributed to the increased permeability to ions diffusion consequential from the degradation of the latex material by attached biofilm (Winfield et al., 2013b). In a related experiment, biodegradable bio-bag and ceramic were proven to be efficient PEM material in MFC (Winfield et al., 2013a). These observations demonstrated that the effect of biofouling on membrane would not be as detrimental to the MFC performance if the material is biodegradable. The biodegradation produces colony craters that enhance membrane permeability to ions (Winfield et al., 2013b) thereby paving a way for application of other biodegradable polymers as PEM material in MFC. Medium-chain-length poly-3-hydroxyalkanoates (mcl-PHA) are biodegradable polymers produced by bacteria under nutrient-deprived conditions. They can be produced from different carbon sources ranging from purified fatty acids to complex sources such as palm oil mill effluent (POME) (Kourmentza et al., 2017). Being biodegradable, they are environmentally benign and sustainable.