Perfluorinated Sulfonic Acid Ion Selective Membranes
Perfluorosulfonic acid ion exchange membrane is a solid polymer electrolyte. It uses polytetrafluoroethylene as the skeleton structure, and the branch is a perfluorovinyl ether structure with a sulfonic acid group at the end group. Due to the high electronegativity of fluorine, the short bond length of the CF bond, high bond energy, and the volume of fluorine atoms is larger than that of hydrogen atoms, it can form a fluorine protective layer with low surface free energy. Therefore, perfluorinated ion exchange membranes have higher mechanical properties. Strength, excellent thermal and chemical stability. In addition, the presence of sulfonate groups makes the ion membrane have cation selective permeability. The strong electron-withdrawing effect of fluorine atoms increases the acidity of perfluorosulfonic acid, thereby enhancing the ion conductivity of the ion membrane.(Yinghao Luan, et al., 2005)
The modified perfluorosulfonic acid ion exchange membrane can be used as a selective potential sensor for the determination of lysine monohydrochloride in a neutral amino acid mixed aqueous solution. Lysine is an indispensable type of amino acid in the human body. Lack of lysine in the body can cause fatigue, headaches, rupture of blood vessels in the eyes, hair loss, loss of muscle mass, loss of calcium, reduced immune response to viral infections, anemia and reproductive dysfunction. Since food contains less lysine and needs additional supplementation, the food industry needs an analytical method for rapid determination of lysine. The measurement principle of perfluorosulfonic acid ion exchange membrane is based on the proton decomposition reaction. The single-charged lysine ions in the solution are transferred to the double-charged ions in the membrane phase, and the protons are almost completely replaced from the membrane.( Bobreshova O V, et al., 2009) Perfluorosulfonic acid membranes can also be used in vanadium redox flow batteries (VRFB). The ideal membrane of VRFB needs to have low vanadium permeability, high conductivity, small area resistance, excellent chemical and mechanical stability, and must have low cost. Perfluorosulfonic acid membranes show good performance in VRFB.
Fig. 1 The schematic representation for the VRFB single cell (Sha'Rani S S, et al., 2018)
- Chlor-Alkali Industry
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- Yinghao Luan, et al. Preparation and performance of perfluorosulfonic acid ion exchange membranes[J]. Journal of Functional Polymers,2005.
- Bobreshova O V, et al. Potentiometric determination of lysine in aqueous solutions using MF-4SK modified perfluorinated membranes[J]. Journal of Analytical Chemistry, 2009.
- Sha'Rani S S, et al. Improved vanadium barrier properties of perfluorinated sulfonic acid membranes for vanadium redox flow battery[J]. Iop Conference, 2018.