Rapid vitrification of Sr-loaded zeolite by microwave sintering for disposal of secondary radioactive wastes: Mechanism and performance

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 498; p. 155214
• Main Authors: Yang, Yang, Shi, Keyou, Liu, Yong, Xie, Yupeng, Zhang, Zhijun, Mai, Yuzhen, Huang, Kun, Zhou, Yi
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.10.2024
• Subjects: Adsorption; Chemical durability; Microwave sintering; Sr-loaded zeolite; Vitrification; Microwave sintering; Adsorption; Chemical durability; Vitrification; Sr-loaded zeolite
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.155214

[Display omitted] •Microwave heating was employed as an energy-event method for the vitrification of as-spent absorbent;•B2O3 addition was testified to lower sintering temperature from 1200℃ to 1000℃；•Microwave sintered Sr-loaded zeolite exhibited excellent chemical durability. The rapid solidification of Sr-loaded zeolite, a potential secondary solid waste, is highly urgent for nuclear post-accident remediation. Microwave heating is first employed to dispose of spent Sr-loaded adsorbent. The adsorption kinetics and isotherm model of zeolite NaX for Sr(Ⅱ) was reported. Meanwhile, the effect of B2O3 additive on the phase evolution, microstructure, and chemical durability was systemically investigated. The results showed that the B2O3 addition could effectively lower the sintering temperature from 1200 ℃ to 1000 ℃ via microwave heating. The stable glass form was successfully obtained with sintering temperature of 1000 ℃, B2O3-doped amount of 25 wt.%, and dwell time of 40 min. The Sr was homogeneously distributed in the sintered matrix without substantial enrichment. Moreover, the leaching rate of Sr in the solidified form was about 1.19 × 10-5 g·m−2·d−1 after 42 days, demonstrating its excellent chemical stability. This study indicated rapid low-temperature vitrification of Sr-loaded zeolite by microwave heating was a promising approach for removal and immobilization of Sr in radioactive wastewater.