Fluoride removal by asymmetrical capacitive deionization using ion-selective biochar electrodes

Friday, November 15, 2019

Joshua Burcham

Department of Chemistry

College of Arts & Sciences

Fluoride contamination in water systems due to industrial and farming activities has been an emerging global concern. Capacitive deionization (CDI), which employs a pair of oppositely charged porous electrodes to remove ions from water, has been known as a cost-effective technology for water desalination. This study aims at exploring the feasibility of activated biochar as a low-cost carbon-based electrode material for capacitive deionization of fluoride ions. The removal capacity was enhanced by grafting sulfonic and amine functional groups to the activated biochar to develop cation and anion selectivity. This reduces the co-ion effect in which half of the energy applied to the porous electrode is used to repel the oppositely charged ions. Physical and electrochemical characterizations was performed to investigate the morphology and capacitive behavior of the ion-selective biochar electrodes. A 3D printed CDI cell was used with NaF solution fed to the cell by a peristaltic pump. The operating voltage was 1.2 V to avoid water electrolysis. The amount of fluoride ions removed from water was investigated using a fluoride ion-selective electrode. A fluoride removal capacity of 8.5 mg g-1 was found. This result is beneficial to advance biochar practical applications in fluoride removal by means of capacitive deionization.

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