Removal of Uranium(VI) in Contaminated Water Using Iron Based Nanoparticles and Simultaneous Adsorption of Uranium(VI) and 2-Chlorophenol by Activated Carbon Fiber supported Titanate Nanotubes

Abstract

Uranium is one of the most detected radionuclides in aquatic systems. Reductive immobilization and adsorption have been commonly practiced to remove uranium from water. In this study, CMC-stabilized iron sulfide (FeS) nanoparticles and FeS- modified zero-valent iron (FeS@Fe0) nanoparticles were synthesized to remove U(VI) from water through concurrent reduction and adsorption. Both types of nanoparticles exhibited high reduction reactivity towards U(VI). A retarded first-order kinetic model was able to interpret the kinetic data. The materials were able to perform well under simulated groundwater chemistry conditions. Spectroscopic and extraction studies revealed that the main removal mechanism of U(VI) was due to concurrent reductive conversion of U(VI) into U(IV) and adsorption of uranyl cations onto the nanoparticles. The immobilized uranium remained stable over prolonged periods of time under simulated groundwater conditions. Activated carbon fiber supported titanate nanotubes (TNTs@ACF) was prepared based on commercial activated carbon fiber and TiO2. TNTs@ACF combines the merits of TNTs and ACF, and was able to simultaneously remove U(VI) cations and 2-chlorophenol (2-CP). TNTs@ACF exhibited synergistic adsorption towards U(VI) and 2-CP when both contaminants were co-present. The synergistic effect is attributed to concurrent surface complexation and π-cation interactions of U(VI) and 2-CP on the material surface. CMC-FeS, FeS@Fe0, and TNTs@ACF hold the potential to facilitate reductive removal of U(VI) and simultaneous removal of metals/radionuclides and organic pollutants in contaminated water and soil.