Sol–Gel Synthesis of CeO2 Nanoparticles Using a Gelatine Template for Effective Adsorptive Removal of Arsenate and Fluoride from Water

Abstract

In this study, CeO₂ nanoparticles were synthesized by the sol–gel method using gelatine templates. The prepared CeO₂ analyzed by analytical techniques displayed the fluorite structure with uniform sizes of 10–25 nm, a BET-specific surface area of 65.8 m²/g, a pore volume of 0.144 cm³/g, and the existence of oxygen vacancies, suggesting their compatibility for adsorption removal of pollutants. The adsorption of arsenate and fluoride on CeO₂ exhibited the maximal adsorption capacity of 224 and 64 mg/g, respectively. The kinetics of the adsorption fitted the pseudo-second-order model perfectly. Compared to fluoride, the adsorption of arsenate was found kinetically more but thermodynamically less favored. It can lie on the more stable complexes formed between arsenate and the prepared CeO₂, the larger size of arsenate ions, and the mesoporosity of the prepared CeO₂. As a result, the pore of the prepared CeO₂ is filled quickly with arsenate ions, becoming full after a specific time that prevents the filling of further arsenate ions. Moreover, the CeO₂ adsorbent demonstrated its high reusability up to 9 times without losing remarkable adsorption capacity (≤10%). Overall, the prepared CeO₂ can be applied for the treatment of drinking water and wastewater in several regions of Vietnam.