고분자 폴리설폰으로 제올라이트를 고정화한 PS-Zeolite 비드의 제조 및 방사성 이온의 제거

Abstract

In order to remove Sr and Cs ions from aqueous solution, PS-zeolite beads were prepared by immobilizing commercial Na-A type zeolite with polysulfone (PS). The prepared PS-zeolite beads were then characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR) and Thermo gravimetric analysis (TGA). The adsorption characteristics of Sr and Cs ions by PS-zeolite beads were well described by the pseudo-second-order kinetic model and Langmuir isotherm. The maximum adsorption capacities by PS-zeolite beads were calculated from Langmuir isotherm as 102.8 mg/g zeolite (65.0 mg/g bead) for Sr ions and 124.2 mg/g zeolite (76.4 mg/g bead) for Cs ions, while the maximum adsorption capacities by powder zeolite were 158.9 mg/g zeolite for Sr ions and 221.9 mg/g zeolite for Cs ions. The adsorption capacities by PS-zeolite beads gained about 60% of the values with powder zeolite. The thermodynamic parameters (G°, H° and S°) calculated from experiments at different temperatures showed that the adsorption of Sr and Cs ions by PS-zeolite is spontaneous and endothermic, and thus the adsorption capacity increases by raising the solution temperature. Meanwhile, impact factors were calculated as 0.58~0.75 for Sr ion and 0.69~0.95 for Cs ion in binary mixture solutions, which showed that the adsorption of Sr ion was more inhibited by the presence of Cs ion. Finally, any sign of zeolite leakage or damage of PS-zeolite beads was not detected even after five adsorption-desorption cycles, while the adsorption capacity of Sr ion by PS-zeolite beads was stably maintained.