The characterization of mesoporous silica (Ms) supporting cerium carbonate (Ms-Ce) and its adsorption performance for defluorination in aqueous solutions.

In this paper, the mesoporous silica (denoted as Ms) was modified by cerium and the optimum preparation conditions were investigated for cerium loaded mesoporous silica materials (denoted as Ms-Ce). The Ms-Ce materials for the fluoride removal performance were characterized by using SEM, XRD, FT-IR and TG-DTA. The Ms-Ce had good defluorination performance due to its large surface area and good-dispersive effect. The results show that cerium is successfully loaded onto the surface of the Ms and the structure of Ms did not change during the loading process. The defluorination loading by Ms-Ce can reach 75.54% under the optimum conditions (nNaHCO₃/nCe = 3.0, nCe/nSi = 0.08 and 90°C drying temperature). The adsorption performance and capacities of Ms-Ce were investigated through adsorption kinetics and adsorption isotherm tests. The maximum fluorine removal efficiency on the loaded materials were that the adsorbent dosage, pH value and adsorption time. They were showed as 1.6 g/L, 3.0 and 240 min, respectively. Dynamics research results showed that the fluoride removal process conformed to pseudo-second order kinetic model. Isothermal adsorption results showed that the fluorine ion adsorption process of Ms-Ce was accord with the Langmuir isotherm adsorption model. The maximum adsorption capacity was 17.96 mg/g. The mainly reaction showed that the active component of cerium carbonate has completed ion exchange with fluoride ion to generate CeCO₃F. [ABSTRACT FROM AUTHOR]