Ca-containing MgAl-LDH/PAN nanofiber membrane for fluoride removal and the recycled derivative for electrocatalytic oxygen

Fluoride contamination in groundwater and the disposal of spent adsorbents remain critical environmental challenges. Herein, a series of monolithic Ca-containing MgAl layered double hydroxide/polyacrylonitrile nanofiber membranes (Mg 2-x Ca x Al-LDH/PAN) were fabricated via electrospinning, which combine the high adsorption performance of LDH with the exceptional separability of nanofibrous matrices. Mg 1.9 Ca 0.1 Al-LDH/PAN showed 96.2% removal efficiency for 10 mg/L F - and maximum adsorption capacity of 16.7 mg/g at 25 °C in a batch reactor, and achieved a specific treatment rate of 150 L/kg/h in a fixed-bed column. The adsorption mechanisms were elucidated through combined experimental and DFT studies. More importantly, rather than following conventional regeneration routes, the spent fluoride-laden adsorbent was converted through pyrolysis into a fluorine-doped carbon-based electrode material. This upcycled material retained a high-surface-area fibrous structure and exhibited enhanced oxygen reduction reaction (ORR) activity compared to its non-fluorinated counterpart. This work presents an “adsorb-and-transform” paradigm that integrates efficient water decontamination with sustainable recovery of functional materials for energy applications. Download: Download high-res image (184KB) Download: Download full-size image