Hydrogenated ceria nanoparticles for high-efficiency silicate adsorption

Abstract

Ce3+ ions from the surface of CeO2 nanoparticles play a key role as active sites in various chemical reactions including silicate adsorption. However, the insufficient concentration of Ce3+ ions at the CeO2 surface is a limitation in the use of CeO2 nanoparticles. In the present study, we introduce hydrogenated CeO2 nanoparticles with plentiful Ce3+ concentration for high-efficiency silicate adsorption. Surface-modified CeO2 nanoparticles were prepared using heat treatment at 800 degrees C for 10 hours with 10% and 20% hydrogen atmospheres to increase oxygen vacancies. During the modification process, two excess electrons from the increased oxygen vacancy formation localized the 4f-state of cerium ions, leading to a valence change in the Ce ions from Ce4+ to Ce3+. As a result, the concentration of Ce3+ ions increased by 45%, from 16.59 to 24.01%, according to hydrogen reduction. The adsorption properties of silicate ions onto hydrogenated CeO2 surfaces were investigated through adsorption isothermal analysis. Finally, the adsorption isotherm results were fitted using the Langmuir and Freundlich equations to elucidate their improved adsorption behaviors.