The BPED bipolar membrane electrodialysis (BMED) stack assembles bipolar membranes and anion- and cation-exchange membranes alternately into a membrane stack. Under a direct current electric field, it converts salts in the feed into corresponding acids and alkalis, achieving salt resource recovery without adding external chemicals.
Structure and Principle
- The membrane stack consists of bipolar membranes, cation-exchange membranes, and anion-exchange membranes arranged alternately in a specific order, forming acid, alkali, and feed compartments.
- Under an electric field, water dissociation in the intermediate layer of the bipolar membrane generates hydrogen ions and hydroxide ions, which combine with ions in the feed to form acid and alkali, respectively.
- The salt concentration in the feed compartment gradually decreases, while the acid and alkali compartments produce reusable acid and alkali solutions.
Product Features
- Electricity is used as the driving force to directly convert salts into acids and alkalis, avoiding chemical consumption in conventional neutralization and regeneration processes.
- The acid and alkali products have relatively high purity and can be directly reused in production or for pH adjustment.
- Modular membrane stack design enables flexible capacity expansion according to treatment scale and product concentration.
- Combined with diffusion dialysis (DD) and conventional electrodialysis (ED), it forms a complete process route for salt resource recovery.
Application Industries
- Preparation of organic acids and alkalis from organic acid salts, such as lactic acid, gluconic acid, tartaric acid, etc.
- Lithium salt conversion and lithium hydroxide preparation in lithium battery and new energy material production.
- Resource recovery and acid-alkali regeneration of industrial waste salts.
- Acid and alkali preparation and recovery in fermentation, pharmaceuticals, and fine chemicals.
Specifications and Models
| Parameter | Unit | Typical value |
|---|---|---|
| Treatment Capacity | m³/d | 2–500 (typical, parallel expansion possible) |
| Product acid / alkali concentration | mol/L | 0.5–3.0 (typical value) |
| Current efficiency | % | 70–95 (typical value, depending on the system) |
| Power consumption per unit product | kWh/kg | Actual operating conditions apply (typical values vary by system) |
| Number of membrane pairs per stack | 对 | 10–300 (typical) |
| Operating temperature | ℃ | 5–40 (typical) |
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.