Na-2-mica of the ideal composition of Na2Mg6Al2Si6O20F 4·xH2O was prepared from a mixture of NaF, magnesium nitrate, SiO2 and calcined kaolinite (the latter serving as a cost-effective aluminosilicate source) at 800°C and was found to excel in Sr removal from solutions at room temperature. This mica was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and 27Al and 29Si magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy. Fundamental studies of nNa+→Mn+ (Mn+ = Sr2+, Ca2+, Li+, K+ and Cs+) equilibria revealed a high selectivity and large capacity for Sr2+ ion uptake. A relatively low-temperature heat treatment (200°C) of the Sr-exchanged mica resulted in collapse of the hydrated interlayer spacings of the mica, which will be useful to immobilize strontium in the stable unhydrated phase. This selective Sr-ion exchanger is expected to be useful for 90Sr removal and its immobilization.
All Science Journal Classification (ASJC) codes
- Materials Chemistry