Enhanced Salt Removal in an Inverted Capacitive Deionization Cell Using Amine Modified Microporous Carbon Cathodes

Area of Science:

• Materials Science
• Electrochemistry
• Environmental Engineering

Background:

• Capacitive deionization (CDI) is a promising technology for water desalination.
• Optimizing electrode materials is crucial for enhancing CDI performance.
• Surface functionalization of carbon materials can tune their electrochemical properties.

Purpose of the Study:

• To functionalize SpectraCarb carbon cloth to create tailored electrode materials for inverted capacitive deionization (i-CDI).
• To investigate the impact of surface modifications on electrode properties and desalination performance.
• To evaluate the potential of these modified electrodes for efficient salt removal.

Main Methods:

• SpectraCarb carbon cloth was treated with nitric acid to introduce negative charges (COO-).
• Further modification with ethylenediamine introduced positive charges (-NH3+) via amine groups.
• Characterization of surface charges, potential of zero charge, and point of zero charge was performed.
• An inverted CDI cell was assembled using acid-treated anodes and amine-treated cathodes.
• Constant-voltage switching operation was employed for desalination tests using NaCl solution.

Main Results:

• Amine-treated carbon exhibited decreased potential of zero charge and increased point of zero charge, opposite to acid-treated carbon.
• The inverted CDI cell achieved a salt removal capacity of approximately 5.3 mg g(-1) at 1.1/0 V.
• Performance showed expanded salt capacity and potential window compared to previous carbon xerogel CDI studies.
• Improved performance was attributed to an enlarged cathodic working voltage window and enhanced microporosity.

Conclusions:

• Surface functionalization of SpectraCarb carbon cloth with acidic and amine groups effectively creates tailored electrodes for i-CDI.
• The developed electrode materials demonstrate enhanced desalination performance, including higher salt removal capacity and wider operating voltage.
• This study highlights the potential of functionalized carbon materials for efficient and scalable water desalination applications.