Bio-inspired interfacial micro-electric field of FeOCl nanosheets for rapid adsorption of perfluorocarboxylic acids (PFCAs)

In this study, a FeOCl adsorbent was demonstrated to rapidly remove perfluorocarboxylic acids (PFCAs). The unique coordination environment led to preferential dissociation of the Cl− in the FeOCl lattice by hydration, forming a high-intensity interfacial micro-electric field. The interfacial micro-electric field could apply an electric driving force to increase the external diffusion flux of PFCAs, thus achieving rapid adsorption (adsorption equilibrium time ∼10 min). In addition, the interfacial micro-electric field excited synergistic adsorption of multiple interactions (complexation, electrostatic interaction, and halogen-bonding interaction), being able to reach 277.01 mg/g for perfluorooctanoic acid (PFOA). Additionally, we developed a continuous flow column using FeOCl to demonstrate its potential for decontaminating drinking water with PFCAs at environmentally relevant concentrations. The FeOCl adsorbent exhibited a bed life of 125,000 BV upon reaching breakthrough concentration of breakthrough concentration of 70 ng/L in dynamic adsorption experiment, which outperformed conventional activated carbon F400D and ion exchange resin IRA67 adsorbents. Spent FeOCl absorbent could be easily regenerated in mild regeneration conditions and maintained a high PFOA removal in subsequent usage cycles. FeOCl demonstrated great potential in the purification of PFCA-contaminated water for household or municipal applications.