Immobilization of uranium-contaminated soil into glass waste by microwave sintering: Experimental and theoretical study

To dispose of uranium-contaminated soil, the microwave sintering technology was used. A series of uranium-contaminated soils were successfully immobilized via microwave sintering for 30 min. When the amount of uranium ranges from 0 wt % to 1 wt %, glass phase occurred in saline-alkali soil, purple soil and red soil, while glass with presence of a crystalline phase occurred in yellow soil. The FT-IR analysis showed that the uranium-contaminated soils were mainly consist of [SiO4] units. The Qn distribution of Si-O tetrahedrons and network connectivity of 1 wt % uranium doped sintered soils were related to the composition of soils. The uranium ions were almost immobilized and evenly distributed in sintered soils. Theoretical results showed that the structures of uranium doped sintered soils were made of Si-O, Al-O and Fe-O tetrahedrons. The O-Si-O linkage was the most preferred one among all linkages and the network forming ability of Si was higher than Al.