Selective fluoride removal in capacitive deionization by reduced graphene oxide/hydroxyapatite composite electrode

Area of Science:

• Materials Science
• Environmental Science
• Electrochemistry

Background:

• Capacitive deionization (CDI) is a promising desalination method known for its environmental friendliness and energy efficiency.
• Conventional activated carbon (AC) electrodes in CDI lack selectivity for anions, leading to inefficient fluoride removal from water and increased energy consumption.
• Fluoride contamination in water poses significant health risks, necessitating effective removal strategies.

Purpose of the Study:

• To develop a novel electrode material for selective fluoride removal in capacitive deionization (CDI) systems.
• To investigate the performance of a reduced graphene oxide/hydroxyapatite composite (rGO/HA) as a fluoride-selective electrode.
• To evaluate the capacity, selectivity, and stability of the rGO/HA electrode for treating fluoridated water.

Main Methods:

• Fabrication of a reduced graphene oxide/hydroxyapatite (rGO/HA) composite material for CDI electrodes.
• Testing the rGO/HA electrode's fluoride removal capacity in a ternary solution containing fluoride, chloride, and nitrate ions.
• Evaluating electrode performance under varying applied voltages and assessing stability over multiple cycles (50 cycles).

Main Results:

• The rGO/HA electrode demonstrated a 4.9 times higher fluoride removal capacity compared to the AC electrode.
• Fluoride removal capacity was optimized with appropriate voltage application.
• The rGO/HA electrode exhibited excellent stability and reusability, maintaining 0.21 mmol g^-1 fluoride removal capacity and 96% regeneration efficiency after 50 cycles.

Conclusions:

• The developed rGO/HA composite is a highly effective and selective electrode material for fluoride removal in CDI systems.
• This material offers a significant improvement over traditional AC electrodes for treating fluoridated water.
• The study presents a viable solution for enhancing the efficiency and selectivity of CDI technology for targeted ion removal.