Bipolar Membrane

• Catalog Number: ACMA00029766
• Category: Main Products
• Burst Strength: >1.0 MPa
• Hydrolysis Voltage: 1.0-1.3 V
• Size: W:1140mm, L:880mm
• Thickness: 0.28mm

Case Study

Diverse Applications of Bipolar Membranes

Pärnamäe R, et al. Journal of Membrane Science, 2021, 617: 118538.

A bipolar membrane (BPM) is a polymer membrane composed of two layers: a negatively charged cation exchange layer (CEL) and a positively charged anion exchange layer (AEL). Protons and hydroxide ions can be produced through a water dissociation mechanism. This unique property makes bipolar membranes attractive for various applications in many fields, such as the (bio)chemical industry, food processing, environmental protection, and energy conversion and storage.
· Bipolar membrane applications:
· Acid-base production and recovery
· Alkoxide production
· Production and recovery of ammonia
· Capture of CO2 and SO2
· Water and sludge treatment
·BPM-assisted energy applications

Bipolar Membranes (BPMs) for Battery Applications

Giesbrecht, Patrick K., and Michael S. Freund. Chemistry of Materials 32.19 (2020): 8060-8090.

The integration of bipolar membranes (BPMs) into electrochemical cells has become a technique for the generation of acids and bases, as well as a method for desalination. BPMs are recognized for their ability to control the half-reaction environment, including maintaining pH gradients, without significant loss of efficiency. Significant advances in BPM design have led to the rapid deployment of BPMs for a wide range of applications, from mineral mining to energy storage and conversion frameworks, iontronics. Ion exchange membranes (IEMs), a polymer hydrophobic structure functionalized with immobilized ions to form hydrophilic ion channels, facilitate the selective ion transport of either cations (CEMs) or anions (AEMs) across the membrane. The IEMs provide an ionic connection between the electrode compartments of an electrochemical cell coupling the two half-reactions, where the ionic current balances the electron flow in the external circuit. IEMs have become key components in alternative energy frameworks, with widespread incorporation into electrolyzers and fuel cells.
Redox-active Lewis acidic metal ions and metal oxides have also been explored for their ability to facilitate WD reactions in solution. Lewis acidic sites and oxygen vacancies on metal oxide and metal hydroxide surfaces promote metastable water adsorption, where water can transfer a proton to an adjacent oxygen atom to form a hydroxyl group that can be stabilized by non-dissociated water. Iron-based systems in particular have been extensively studied as WD catalyst layers in BPMs. Initial reports observed WD enhancement in the presence of Fe(OH)3 particles, which can lead to Fe ion loss during operation due to poor immobilization in the IL, resulting in CEL and electrode poisoning, reducing the efficiency of the BPM system due to increased impurity levels. The addition of stabilizing matrices such as mixed metals, metal-organic frameworks (MOFs), sol-gels, polymers, or carbon supports retains the metal ion content in the IL, where the functional groups of the support can also contribute to WD enhancement in the IL. Among them, the incorporation of Feions into a polyethyleneimine (PEI) matrix at the BPM IL improved the catalytic ability of the WD catalyst layer while minimizing Fe loss during operation. Alternative Lewis-acidic metal ions and metal oxides, such as titania and alumina, have also been explored as WD (photo)catalysts and enhance the WD in BPM ILs.

Bipolar membrane production of acids and bases

Xu, Tongwen. Desalination 140.3 (2001): 247-258.

Bipolar membrane (BM) is a composite membrane composed of at least one layer of cation selective membrane (with negative fixed charge) and one layer of anion selective membrane (with positive fixed charge) in a layered ion exchange structure. Similarly, the discovery of semiconductor N-P junctions has led to the invention of many new semiconductor instruments, and the combination of anion and cation exchange layers has brought many novelty, such as the separation of monovalent and divalent ions, anti deposition, anti fouling, hydrolysis, etc. Specifically, hydrolysis based on bipolar membrane technology is considered one of the most promising fields.
Bipolar membranes produce acids and bases from corresponding salts, which is a well-known technique derived from the dissociation of bipolar membranes. In this process, there are two main types of battery arrangements: one is a two compartment unit, and the other is a three compartment unit. The dual chamber unit structure is simple, but the base generated from the cathode tends to be transported through the anion membrane to the acid chamber, where it dissociates from the acid produced by water, thereby reducing the current efficiency. This drawback is overcome through a three compartment unit. In addition, in the three-layer structure, there is no direct contact between the cation layer and the acid, and between the anion layer and the base, resulting in a significant increase in the duration of the membrane. In fact, with this configuration, the generated acid and base can reach up to 6 mol/L. This technology can be used in industrial production to produce silicic acid (H2SiO3) using Na2SiO3 as raw material. Compared with traditional ion exchange methods, the energy consumption can be reduced from 1 kwh/kg to 0.6 kwh/kg at a current density of 10-12 mA/cm2