Selective electrochemical water treatment using capacitive deionization for high-recovery contaminant removal
Capacitive deionization (CDI) technology that selectively removes unwanted ions from water without removing beneficial species. This membraneless electrochemical approach uses nanoporous activated carbon to target hardness ions and other contaminants at low energy cost, enabling up to 95% water recovery for industrial and municipal water treatment.
Overview
Water treatment today relies heavily on reverse osmosis (RO), a membrane-based process that removes nearly all dissolved species. While effective, RO is energy-intensive and inefficient in applications where only certain contaminants need to be removed while others are beneficial. This proposal introduces capacitive deionization (CDI), a membraneless electrochemical technology that can selectively target unwanted ions while preserving desirable ones, achieving high water recovery at low energy consumption.
CDI uses inexpensive nanoporous activated carbon electrodes that are electrically charged to electrostatically attract and remove specific ions from solution. When discharged, the electrodes release the captured ions as a concentrated waste stream without requiring added chemicals. The technology has demonstrated the ability to preferentially remove hardness ions such as calcium over salt ions such as sodium, making it a versatile tool for tailored water treatment.
Technical specifications
Core technology:
- Capacitive deionization using nanoporous activated carbon electrodes
- Membraneless electrochemical design eliminates membrane fouling and replacement costs
- Size-based selectivity mechanism: smaller hydrated ions are stored preferentially over larger ones
- Selectivity tunable by adjusting operating conditions: can favor salt ions over mineral ions, or mineral ions over salt ions
Key performance targets:
- Selective hardness ion removal (calcium) while preserving salt ions (sodium)
- Water recovery target of 95%, up from previously demonstrated 80%+
- Discharge stream using only 5% of treated water volume
- Long-term stability validated through 1000 accelerated cycles
Potential applications:
- Industrial water softening and hardness management
- Municipal water treatment with selective contaminant removal
- Mining and mineral processing water streams
- Any application requiring targeted ion removal rather than total desalination
Technology readiness level
The CDI technology has been demonstrated at lab scale with selective removal of hardness ions over salt ions. The research group at Technion has built and tested lab-scale CDI cells and pioneered the concept of size-based selectivity. Current work focuses on pushing water recovery from over 80% to a target of 95% while maintaining selective functionality. Future validation will include long-term performance testing over 1000 accelerated cycles to detect and diagnose any performance degradation, particularly potential scaling issues caused by high mineral content during discharge. The technology is at an early-to-mid stage of development, with proven selectivity mechanisms and ongoing optimization for commercial readiness.
About Technion - Israel Institute of Technology
Technion – Israel Institute of Technology is a leading public technological university in Haifa with a STEM‑intensive, entrepreneurial culture and a globally engaged research community. Companies engage via co‑located labs and shared core facilities on campus, with access to prototyping and fabrication shops and contract research. The medical faculty’s integration with major teaching hospitals enables clinical studies and translation, and the campus lies within Israel’s high‑tech corridor, linking partners to startups and multinational R&D centers. Research is backed by national funding from the Israel Science Foundation and the Israel Innovation Authority, plus European programs like Horizon Europe and binational foundations; a dedicated technology transfer office supports IP, licensing, and startup formation.
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