A bipolar membrane is a composite of an anion-exchange layer, a cation-exchange layer, and an intermediate catalytic layer. Under a direct-current electric field, water in the intermediate layer dissociates into hydrogen ions and hydroxide ions, directly converting salt into the corresponding acid and alkali. It is the core material of bipolar membrane electrodialysis (BMED).
Structure and Principle
- Composite structure consisting of an anion-exchange membrane layer, a cation-exchange membrane layer, and a water dissociation catalytic layer between them.
- Under a direct-current electric field, water molecules in the intermediate layer dissociate to generate hydrogen ions and hydroxide ions, which migrate to the two sides respectively.
- Combined with anion- and cation-exchange membranes to form a membrane stack, it can convert salt solutions into acid and alkali without adding chemical agents.
Product Features
- Can directly convert salt into acid and alkali, avoiding chemical dosing and by-products in conventional processes.
- Low water dissociation voltage helps reduce the electricity consumption per unit of product.
- The concentration of the product acid and alkali can be adjusted according to operating conditions to suit different reuse and production requirements.
- Combined with electrodialysis (ED) and diffusion dialysis (DD), it can form a complete process chain for acid and alkali recovery.
Application Industries
- Green production process for converting organic acid salts into organic acids and alkali.
- Acid and alkali preparation and material recycling in lithium salt and sodium salt systems.
- Separation and acid and alkali recovery for fermentation broth, amino acids, and other bio-based products.
- Supporting process for resource recovery conversion of industrial waste salt and zero liquid discharge.
Specifications and Models
| Parameter | Unit | Typical value |
|---|---|---|
| Membrane structure | — | Anion-exchange membrane layer / catalytic layer / cation-exchange membrane layer composite |
| Water dissociation voltage | V | 0.8–1.2 (typical value) |
| Current efficiency | % | 70–95 (typical value, depending on the system) |
| Product acid / alkali concentration | mol/L | 0.5–3.0 (typical value) |
| Operating temperature | ℃ | 5–40 (typical) |
| Applicable pH range | — | Actual operating conditions apply (typical values vary by system) |
The data in the table are common ranges for similar equipment and are for selection reference only; specific specifications, models, materials, connections, and control methods must be confirmed during the selection stage based on water quality, treatment scale, and site conditions.