Highly efficient and rapid fluoride scavenger using an acid/base tolerant zirconium phosphate nanoflake: Behavior and mechanism

Zirconium phosphate (ZrP) has been developed as an efficient adsorbent, since the 1960s, but most research involving ZrP focuses on metal cation (e.g. K⁺/Ca²⁺/Pb²⁺/Cu²⁺) capture. Herein, we synthesized a ZrP nanoflake by simple in-situ precipitation procedures and successfully explored a new application area for it: fluoride scavenging. Completely different from the conventional metal oxides, the resultant ZrP exhibits good chemical stability in acidic or basic environments. More importantly, preferable fluoride uptake can be achieved at high concentrations of competitive anions (SO4²⁻/Cl⁻/NO3⁻) addition, exceeding that of commercial D201, activated Al2O3, manganese sands, etc. Kinetic results further demonstrate its efficiency for approaching equilibrium in 5 min. Furthermore, the actual application proves superior treatment capacities of approximately 1800 kg and 3900 kg for groundwater and acidic wastewater treatment, respectively and the exhausted materials can be readily regenerated using 5% NaOH solution for at least five cycles. XPS and FT-IR investigation reveal that the preferable fluoride adsorption can be ascribed to strong inner-sphere complexation achieved by ZrF bonds. All the results demonstrate that the representative ZrP nanoflake is an efficient and rapid fluoride-removing candidate for cleaning water.