Removal of fluoride from drinking water by cellulose@hydroxyapatite nanocomposites

Cellulose@hydroxyapatite (HA) nanocomposites were prepared in NaOH/thiourea/urea/H2O solution via situ hybridization. The composite materials combine the advantage of cellulose and HA with the high specific surface area and the strong affinity toward fluoride. The composite materials were characterized by FTIR, SEM, XRD, TG and XPS, and the adsorption of fluoride was investigated. Adsorption kinetics indicated the adsorption equilibrium of fluoride was within 360 min and the adsorption process was well described by the pseudo-second-order kinetic model. The Langmuir and Freundlich isotherm models could fit the experimental data well. At the initial fluoride concentration of 10 mg/L, the residual concentration using above 3 g/L adsorbent dose could meet the drinking water standard of WHO norms. Furthermore, the coexisting anions had no significant effect on fluoride adsorption.