Iron (III) oxyhydroxide powders with TEMPO-oxidized cellulose nanofibrils: effective adsorbents for removal of fluoride ion in water

Fluoride ions are toxic, and F − in groundwater for drinking should be sufficiently reduced to be less than the regulated concentration. In this study, cellulose nanofibril-containing iron oxyhydroxide (FeOOH) powders were synthesized, and their F − adsorption behaviors were studied under various conditions. 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibrils (CNFs) were added to 0.1 M FeCl 3 , and 1 M NaOH was added to the FeCl 3 /TEMPO–CNF mixture to prepare FeOOH precipitates at various FeOOH/TEMPO–CNF mass ratios. When TEMPO–CNFs were present in the FeCl 3 solution, the FeOOH/TEMPO–CNF precipitates were quantitatively obtained by straightforward filtration with filter paper; enabled by the larger size (> 300 µm) of the FeOOH/TEMPO–CNF precipitates than the FeOOH precipitates (