Capacitive Removal of Fluoride Ions via Creating Multiple Capture Sites in a Modulatory Heterostructure
Guizhi Wang, Tingting Yan, Junjie Shen, Jianping Zhang, Dengsong Zhang
Abstract
Fluoride pollution has become a major concern because of its adverse effects on human health. However, the removal capacity of defluorination agents in traditional methods is far from satisfactory. Herein, capacitive removal of F– ions via creating multiple capture sites in a modulatory heterostructure has been originally demonstrated. The heterostructure of uniformly dispersed Al2O3 coating on hollow porous nitrogen-doped carbon frameworks was precisely synthesized by atomic layer deposition. An exceptional F– ion removal efficiency at 1.2 V (95.8 and 92.9% in 5 and 10 mg/L F– solutions, respectively) could be finally achieved, with a good regeneration ability after 20 consecutive defluorination cycles. Furthermore, we investigated the removal mechanisms of F– ions by in situ Raman, in situ X-ray diffraction, and ex situ X-ray photoelectron spectroscopy measurements. The promotional removal capacity was realized by the multiple capture sites of the reversible conversion of Al–F species and the insertion of F– ions into the carbon skeleton. This work offers an important new pathway and deep understanding for efficient removal of F– ions from wastewater.