Electroblown titanium dioxide and titanium dioxide/silicon dioxide submicron fibers with and without titania nanorod layer for strontium(II) uptake

Abstract

Nuclear power is a clean alternative to fossil fuels. However, the use of nuclear energy generates hazardous fission products of which 90Sr is the second most important. To remove Sr2+ from aqueous solutions, we synthesized submicron TiO2 and TiO2/SiO2 composite fibers with Ti : Si molar ratios of 3 : 1 (3TiO2–1SiO2) and 1 : 1 (1TiO2–1SiO2) utilizing a novel electroblowing technique. After calcination at 500 °C, the TiO2 and 3TiO2–1SiO2 fibers had a predominantly anatase TiO2 structure with portions of rutile and brookite but the crystallites in the 3TiO2–1SiO2 fibers were smaller due to the SiO2 component. The 1TiO2–1SiO2 fibers were quasi-amorphous. Rutile TiO2 nanorods were grown on the fibers by a hydrothermal method. The rods seemed to grow only on the TiO2 domains of the fiber surface, which affected their size and morphology. In batch adsorption experiments all the fibers had excellent Sr2+ uptake with the hydrothermally modified TiO2 fibers having the highest distribution coefficient (Kd) of 3,490,000 mL g−1. The results show that both anatase and rutile TiO2 can efficiently adsorb Sr2+ from an aqueous environment. Hardly any damage was observed in the nanorods on the TiO2 fibers in a column operation test with flow rates up to 74 mL h−1 which is promising for the use of the fibers in industrial column mode wastewater treatment.