Electrodialysis Using Zero-Gap Electrodes Producing Concentrated Product Without Significant Solution Resistance...

Area of Science:

• Chemical Engineering
• Electrochemistry
• Separation Science

Background:

• Electrochemical separations are vital for producing dilute and concentrated streams.
• Traditional methods face economic challenges due to high ohmic losses and low current densities.
• Optimizing cell design is crucial for improving efficiency and reducing energy costs.

Purpose of the Study:

• To present a new electrochemical cell design that bypasses the dilute product stream.
• To enhance the economics and performance of electrochemical separation systems.
• To enable higher current densities and reduce balance-of-plant costs.

Main Methods:

• A three-chamber cell configuration with anion and cation exchange membranes was developed.
• Zero-gap membrane electrode assemblies were employed to improve cell voltage.
• The study analyzed ion transport and collection efficiency under varying current densities.

Main Results:

• The novel cell design eliminates current flow through the dilute stream, reducing ohmic losses.
• Higher current densities and faster feed flow rates were achieved compared to traditional electrodialysis.
• Ion collection efficiency increased with current, attributed to enhanced convective mass transfer.
• The system demonstrated a lower voltage penalty for product recovery.

Conclusions:

• The developed cell configuration offers significant advantages for electrochemical separations.
• This approach improves energy efficiency and reduces operational costs.
• The design is suitable for applications involving suspended solids and high throughput.