Facile synthesis of Ce(III)-rich cerium oxyhydroxide and its unselective adsorption of Sb(III) and Sb(V) via oxygen vacancies

The introduction of oxygen vacancies (OVs) into metal oxide materials is an effective method for modifying the surface properties of environmentally functional materials. However, limited attention has been paid to their roles as pollutant adsorbent. In this study, Ce(III)-enriched cerium oxyhydroxide particles (CeO(OH)2-OVs@CS) were prepared using a drop-in phase separation method and then used as adsorbents to address the challenges of conventional metal oxides that display notably lower adsorption efficiencies for Sb(V) than Sb(III). Within 60 min, more than 96 % of both Sb(III) and Sb(V) with an initial concentration of 50 mg/L were removed, with only a 2 % difference between them. XRD, XPS, EPR, and FT-IR results demonstrated that chitosan served as a carrier for Ce nanoparticles and, due to its reductive characteristics, enhanced the air stability of Ce(III), thereby creating more OVs. Meanwhile, chitosan's abundant functional groups such as OH, NH2, and CO in its structure can also facilitate the binding of Sb species onto CeO(OH)2. Density functional theory (DFT) calculations also indicated that antimonate ions were more prone to binding with OVs compared with defect-free crystal surfaces. Additionally, CeO(OH)2-OVs@CS showed great removal performance for organic ligands in antimony(III) potassium tartrate solution, and about 97 % of tartaric acid was removed simultaneously.