Electrodialysis Plastic Spacer

Property

The electrodialysis (ED) spacer is a crucial component in ED stacks, acting as a mechanical support to maintain channel spacing between ion-exchange membranes, promoting fluid turbulence for better mixing, and reducing concentration polarization for efficient ion transport, significantly impacting overall energy efficiency and water quality. These usually mesh-like or net-like structures are designed with specific geometries (like diagonal patterns) to enhance mass transfer, reduce power consumption, and can even be chemically modified (e.g., ion-exchange spacers) to improve performance further.

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Main Functions and Applications

An electrodialysis spacer performs vital roles in the stacks:
Mechanical Support: It maintains a precise, uniform distance between the Cation Exchange Membranes (CEM) and Anion Exchange Membranes (AEM). Without it, the membranes would touch, short-circuiting the system or blocking the fluid flow. To prevents membranes from touching and collapsing, ensuring defined flow paths.
Flow Channel Creation: It creates the path through which the "diluate" (clean water) and "concentrate" (brine) streams flow.
Turbulence Promotion: This is perhaps its most important job. By disrupting the flow, the spacer prevents concentration polarization-a phenomenon where ions build up near the membrane surface, creating a "clog" that increases electrical resistance.
Sealing (Gasket Function): Many spacers are integrated with a perimeter gasket that prevents the salt water from leaking out of the stack or mixing between the diluate and concentrate chambers.
Hydrodynamic Mixing: Creates turbulence, breaking down boundary layers near membranes, which boosts mass transfer of ions.
Reduces Polarization: Minimizes concentration build-up (polarization) that hinders ion flow, improving performance. Improves Efficiency: Better mixing and reduced polarization lead to lower electrical resistance and less energy use.