An Electroactive and Regenerable Fe3O4@Polypyrrole Nanocomposite: Fabrication and Its Defluorination in an Electromagnetic Coupling System

An electrochemically regenerable Fe3O4@polypyrrole (PPy) core–shell nanocomposite with superparamagnetism for selective fluoride ion removal from wastewater is fabricated. The rapid fluoride ion uptake kinetics is realized in a batch experiment due to the good affinity of PPy toward fluoride ions. It is found that the pseudo-second-order model can well describe the adsorption kinetics and the equilibrium data fits well with the Freundlich isotherm model. The spontaneity and exothermic nature of the fluoride ion adsorption are confirmed based on thermodynamic parameter analysis. In an electromagnetic coupling system, the nanocomposites exhibit a high regeneration efficiency around 95% in each cycle and only a slight drop in the capacity retention rate of fluoride ion adsorption even after 20 adsorption–regeneration cycles. This intelligently magnetic nanocomposite should be a promising alternative material for fluoride ion removal from wastewater.