Studies on novel nano-bimetal doped cellulose nanofibers derived from agrowaste towards deflouridation

Cellulose nanofibers were extracted from sugarcane bagasse. Zerovalent‑iron (ZVI)/Zirconium(IV) (Zr)/ZVI-Zr doped cellulose nanofibers were prepared, characterized and evaluated for fluoride removal. The prepared nanofibers could effectively remove fluoride within a wide pH range of 3.0 to 8.0. The equilibrium reached within 3 h and the adsorption capacities followed the order ZrZVICNF > ZrCNF > ZVICNF. The Langmuir adsorption capacity of ZrZVICNF was 35.70 mg/g, much higher than various commercial adsorbents. Nitrate, chloride, sulphate, phosphate, has insignificant effect on fluoride adsorption and higher concentrations of bicarbonate and silicate ions affected fluoride sorption. Furthermore insignificant amount of Zr(IV) ions were leached during adsorption owing to its efficient complexation with hydroxyl groups of cellulose and the adsorbent could be successfully regenerated. Spectroscopic analysis revealed that fluoride ion complexed with both Zr(IV) and Fe(II)/Fe(III) ions. Thus high fluoride uptake capacity, faster kinetics, applicability at wide pH range, makes ZrZVICNF as attractive sorbent for defluoridation.