Fluoride Removal Using Capacitive Deionization with Electrodes Coated on Both Sides

The present study was focused on the fabrication of a device to remove fluoride using capacitive deionization (CDI). The conventional CDI device was modified such that electrodes coated on both sides could be used. The electrodes were prepared by mixing activated carbon (AC), graphite powder (GP), polyvinylidene fluoride (PVDF), and N, N-dimethylacetamide (NDMAc). The proportion of the constituents was varied to obtain the optimum composition for the most efficient electrodes. Electrodes with composition of AC:GP:PVDF=70∶16∶14 wt% were found to have sufficient mechanical strength and favorable capacitive characteristics for the electrosorption of fluoride ions. The maximum removal efficiency obtained with single-side coated electrodes was 90.38%±1.33% under 45 min, whereas for electrodes coated on both sides, the maximum efficiency achieved was 97.38%±0.44% under 25 min. The study was performed using a batch-type CDI device. The device could operate effectively at a low voltage of 1.5 V, making it an environment-friendly and efficient technology. The cost involved for the treatment of water was USD 0.039/L.