Nanocomposite of Ceria and Trititanate Nanotubes as an Efficient Defluoridating Material for Real-Time Groundwater: Synthesis, Regeneration, and Leached Metal Risk Assessment

Abstract

Ceria-incorporated trititanate nanotube composite (CTNC) was synthesized via a simple two-step wet chemical route for efficient fluoride removal not only from synthetic water but also from groundwater. The synthesized nanomaterial was systematically characterized for its physical and chemical properties. CTNC was shown to be highly porous with a surface area of 267 m2/g. The high surface area exposed majority of its adsorption sites, that is, surface hydroxyl groups, for fluoride removal. The plausible adsorption mechanism deduced based on FTIR and XPS data showed that ion exchange between the surface hydroxyl groups and the fluoride ions in water played a vital role in defluoridation by CTNC. A novel approach was used to quantify the adsorption sites with the use of BET and thermogravimetric analysis. TEM images confirmed the morphology of CTNC to be nanotubes decorated with ceria particles. The analysis of treated water samples for the metal ion content was carried out by an ICP-MS technique. CTNC exhibited characteristics of an ideal adsorbent such as high adsorption capacity, faster kinetics, pH independent adsorption, good regeneration, and negligible leaching of metal ions into the effluent. These attractive characteristics enabled the applicability of CTNC for real-time use.