Potential use of CeO₂, TiO₂ and Fe₃O₄ nanoparticles for the removal of cadmium from water

Financial support was provided by the Spanish Ministerio de Medio Ambiente y Medio Rural y Marino (Project Exp. 007/RN08/03.1). Sonia Recillas thanks Universitat Autònoma de Barcelona for the award of a post-doctoral fellowship. Altres ajuts: MAPAMA/007/RN08/03.1 Inorganic nanoparticles (NPs) of cerium oxide (CeO₂), iron oxide (Fe₃O₄) and titanium oxide (TiO₂) were studied for the removal of dissolved cadmium from water at concentrations ranging from 25 to 350 mg/L. Adsorption was the predominant mechanism for sequestration, and particularly efficient cadmium removal was demonstrated for Fe₃O₄ NPs. Experimental data were fitted to three different adsorption isotherms: Langmuir, Freundlich and Temkin. The best fit was obtained for the Freundlich isotherm (R² > 0.96 for all NPs). Adsorption was shown to follow pseudo second-order kinetics (R² ⩾ 0.91 for all NPs). All three NPs showed some removal of cadmium in aqueous solution, but after 72 h of process, Fe₃O₄ NPs showed a higher capacity of cadmium adsorption (101.1 mg Cd/g NP) than CeO₂ NPs (49.1 mg Cd/g NP) or TiO₂ NPs (12.2 mg Cd/g NP). These results demonstrate the potential use of this NPs to remove dissolved cadmium at high concentrations.