Titanium Hydroxide as a New Inorganic Fluoride Ion Exchanger

Although TiO2 exhibits a small fluoride ion exchange capacity, it was found that titanium hydroxide, Ti(OH)4, can exchange fluoride ion with large saturation capacity of 1.60m·mol/g. Although the H2PO4- interferes with the F- exchange, the amount of F- exchange of Ti(OH)4 was hardly changed by the coexistence of Cl-, NO3-, and SO42-. The capacity for F- exchange was almost unchanged over 4 times repetition of ion-exchange and desorption and furthermore, the elution of Ti was negligibly small. Consequently, Ti(OH)4 is expected to be a new inorganic F- exchanger for the removal of fluoride ion from wastewater.