PDF Publication Title:
Text from PDF Page: 003
Membranes 2022, 12, 602 3 of 18 1.1.2. Without Separator It is theoretically possible to prepare hypochlorite directly by making electrolysis of a NaCl solution, leaving the reaction products in contact at the anode and cathode according to reaction II-1. Various side reactions may also occur, depending, in particular, on the electrodes used and the operating voltage, such as the oxidation of hypochlorite to chlorate [4,5,7]. Although this type of cell has the advantage of simplicity, it has many disadvantages. This includes the low concentrations obtained (<1% active chlorine), the impossibility of separating the production of chlorine and soda if desired, and the release of a dangerous mixture of hydrogen and oxygen. 1.1.3. With Separator The introduction of a separator makes it possible to separate the production of chlorine and soda and to avoid the hydrogen oxygen mixture. However, it is necessary that it allows electrical charges to pass through by ionic transfer. To this end, two solutions are used: either a simple porous system (diaphragm) or a selective system for ionic transport. In all cases, they must introduce the lowest possible resistance so as not to penalize energy consumption. The materials used must also be able to resist the oxidizing species produced. • Diaphragm The porous separators were initially made of asbestos. With the prohibition of the use of this material, different solutions were proposed. The most common solution is to use a porous Teflon, sometimes supplemented with inclusions of particles such as ceramics or ion- exchangers [7]. An alternative solution entails the use of conductive ceramic membranes [5]. • Ion-exchange membranes (IEMs) Ion-exchange membranes are polymeric membranes containing ionizable functional sites of positive (AEM) or negative (CEM) charge. They are appealing thanks to their good electrical conductivity and their transfer selectivity. However, they must be resistant to oxidizing environments. Therefore, perfluorosulfonic polymers are preferred in case a separate production of chlorine and sodium hydroxide is desired. The addition of a layer bearing carboxylic functions makes it possible to practically avoid any transfer of OH ions and leads to soda yields of up to 50% [5,8,9]. Due to the high cost of this type of material, other types of membrane have been the subject of research. In 2021, Kim et al. [5] obtained similar productions with Nafion®117 and 324 industrial membranes as with homemade SPEEK membranes for the production of low-concentration hypochlorite applicable to water treatment which does not require only concentrations below 1000 ppm. The three membranes give equivalent yields and concentrations. The use of SPEEK membranes, therefore, makes it possible to reduce costs thanks to the lower price of the membranes but also thanks to their lower electrical consumption. However, no lifespan study has been carried out. In 2020, Mohammadi et al. [10] compared the use of an anionic membrane based on polystyrene/divinyl benzene, including quaternary ammonium functions with two cationic membranes having sulfonic functions, with or without a Teflon weft. Operating parameters are selected based on use by direct injection into water supply systems with chlorine concentrations ranging from 355 to 916 mg·L−1. They show that the best quality of the product preservation is obtained with the Teflon reinforced cationic membrane; however, the quality of production with MEA proves to be mediocre. In the same study, Mohammadi et al. [10] also use a bipolar membrane whose performance is intermediate compared to the other two types. This type of process with MEI separator is reputed to be the most economically appealing. It tends to currently replace the old devices.PDF Image | Zero Gap Electrolysis Cell for Producing Bleach
PDF Search Title:
Zero Gap Electrolysis Cell for Producing BleachOriginal File Name Searched:
membranes-12-00602.pdfDIY PDF Search: Google It | Yahoo | Bing
Salgenx Redox Flow Battery Technology: Power up your energy storage game with Salgenx Salt Water Battery. With its advanced technology, the flow battery provides reliable, scalable, and sustainable energy storage for utility-scale projects. Upgrade to a Salgenx flow battery today and take control of your energy future.
CONTACT TEL: 608-238-6001 Email: greg@salgenx.com (Standard Web Page)