Anion Exchange Membranes
Anion exchange membrane refers to a semi-permeable membrane containing anion functional groups. During operation, because the positively charged groups on the membrane pore framework constitute a strong positive electric field, only anions can penetrate, but cations cannot. At the same time, it does not permeate gases such as oxygen or hydrogen during operation. The ion transfer between the external solution and the membrane is not true ion exchange, but selective dialysis. So its essence is an alkaline electrolyte. Because the anion exchange membrane can be used in an alkaline environment, which makes it possible to use non-platinum/low-platinum catalysts, the material cost of the anion exchange membrane is greatly reduced while achieving the same performance as the cation exchange membrane. The anion exchange membrane does not require regeneration and other steps and can be operated continuously. The anion exchange membrane also has the advantages of alkali resistance, oxidation resistance, chloride resistance, and diffusion and dialysis to recover acid.
Preparation of strong acid cation exchange resins
Most of the traditional anion exchange membranes use aromatic polymers as the backbone, such as polysulfone, polyether ether ketone, polyether sulfone ketone and so on. The quaternary ammonium is then introduced as a conductive functional group by chloromethylation. However, chloromethylation is carcinogenic and potentially harmful to human health. Therefore, researchers from various countries have devoted themselves to the development of anion exchange membrane preparation routes that avoid the use of chloromethyl ether. Chain halomethyl alkyl ethers are used as preparation methods for halomethylation reagents and the like. Using bromination instead of chloromethylation can also prepare homogeneous anion exchange membranes. Based on polyphenylene ether as the substrate, bromomethyl groups are generated by the methyl bromination treatment on the benzene ring of the polymer, and the functional grouping or crosslinking reaction with different amines can be used to obtain a series of different functional groups. Phase anion exchange membrane.
Fuel cells are an attractive alternative energy source in the 21st century. Proton exchange membrane (PEM) as an electrolyte has been used in the automotive field. However, the high cost of catalysts and electrolyte membranes limits their large-scale applications. The principle of anion exchange membrane (AEM) is similar to that of proton membrane, which can reduce or eliminate the disadvantages of proton membrane. In the next few years, anion exchange membrane fuel cells (AEMFC) will be used in many power applications, including automobiles, power generation, and portable power sources.( Dong X W, et al., 2015)
- Sea water desalination
- Tap water softening
- Electrodialysis, diffusion dialysis
- Electrochemical sensing and fuel cell
- Dong X W, et al. Development of anion-exchange membrane for anion-exchange membrane fuel cells[J]. Material Research Innovations, 2015.