Zirconium‐2‐Imidazolidinethione Functionalized Reduced Graphene Oxide Aerogel for Efficient Removal of Fluoride Ions and Anionic Dyes from Aqueous Solutions: Multivariate Process Optimization

Abstract A multifunctional aerogel (zirconium‐2‐imidizalodinethione‐reduced graphene oxide aerogel, Zr‐IMDT/rGOA) is synthesized by functionalizing graphene oxide with ZrCl 4 and 2‐imidazolidinethione through one‐pot hydrothermal reduction and subsequent freeze drying. The aerogel is employed for the removal of anionic pollutants. Zr‐IMDT/rGOA shows good removal performance for both fluoride ions (F − ) and anionic dyes (Alizarin Red S (ARS) and Eosin Y (EY)). The removal efficiency of F − is 97.96% at pH 4.6, time 30 min, an initial concentration of 10 mg L −1 , and an adsorbent dosage of 0.01 g as optimized by the Box Behnken Design in response surface methodology. . Brouers‐Sotolongo isotherm model fits well with the equilibrium sorption data and maximum sorption capacity ( Q max ) of 328.28, 694.00, and 1449.28 mg g −1 is obtained for F − , ARS, and EY, respectively. Fractal‐like pseudo‐second‐order kinetic model is best suited to the kinetic data and >50% removal is attained for all analytes within 5 min indicating fairly fast kinetics. Zr‐IMDT/rGOA shows good selectivity for F − in the presence of counter ions (Cl − , NO 3 − , SO 4 2− , HCO 3 − , and H 2 PO 4 − ) and could be regenerated up to five cycles with >90% removal. The synthesized aerogel is successfully applied to remove F − from groundwater, river water, and tea infusion.