Mesoporous zirconium pyrophosphate for the adsorption of fluoride from dilute aqueous solutions

Mesoporous zirconium pyrophosphate(ZPP) adsorbents were synthesized, with six quaternary ammonium salts (Quats), namely, Octyltrimethylammonium (OTMA, C8), Decyltrimethylammonium (DCTMA, C10), Dodecyltrimethylammonium (DDTMA, C12), Tetradecyltrimethylammonium (TDTMA, C14), Hexadecyltrimethylammoium (HDTMA, C16), and Octadecyltrimethylammonium (ODTMA, C18), as template for studying fluoride adsorption. Quats of long carbon chain length significantly affected the specific surface area mesoporous ZPP adsorbents. C18-ZPP exhibited largest adsorption density. Fluoride density remained constant at pH < 7.0, decreased sharply increased beyond 7, became minimal > 10–11. Langmuir isotherm described characteristics well. Results showed that synthesized C18 Zr to molar ratio 0.57:1 best capacity (32 mmol/g) among all prepared various ratios. two-fold increase in removal compared plain ZPP. The reusability was assessed by running least five cycles. is a promising adsorbent from water much enhanced capacity, regenerability, reusability.