Interplay between storage temperature, medium and leaching kinetics of hazardous wastes in Metakaolin-based geopolymer

• Published in: Journal of hazardous materials 2020-02, Vol.384, p.121377-121377, Article 121377
• Main Authors: He, Peigang, Cui, Jingyi, Wang, Meiling, Fu, Shuai, Yang, Hualong, Sun, Chengyue, Duan, Xiaoming, Yang, Zhihua, Jia, Dechang, Zhou, Yu
• Format: Article
• Language: English
• Subjects: Geopolymer; Hazardous wastes storage; Immobilization mechanism; Leaching environment
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2019.121377

[Display omitted] •Metakaolin-based geopolymer was prepared for hazardous wastes storage.•Temperature and medium-dependent leaching kinetics of hazardous wastes were probed.•Geopolymer showed better immobilization performance than Portland cement, ceteris paribus.•Microscopic leaching mechanisms were revealed under different leaching conditions. Notwithstanding the success of carbon-free nuclear power in the new energy industry, an effective way to address nuclear contamination is still lacking. As a generally accepted method to date, immobilization of radioactive nuclear wastes with inexpensive and environment-friendly matrix such as geopolymer has attracted extensive attention. In this contribution, Na-based and K-based metakaolin geopolymer were prepared to encapsulate simulated radioactive Cs+ and Sr2+ under different temperatures and environments during long-term leaching tests. The temperature-dependent and environmental-dependent leaching kinetics as well as their dominant leaching mechanisms have been revealed. The results showed that Na-based and K-based geopolymer exhibited better immobilization performance than that of Portland cement, ceteris paribus. For the immobilization of Cs+, Na-based geopolymer showed lower leaching rate than K-based geopolymer under the same leaching conditions. Both higher temperature and salt solution accelerated the leaching behaviors of Sr+ and Cs2+ from the encapsulation matrix. This contribution sheds light on understanding the dominant leaching mechanisms of hazardous elements under different storage environments and highlights the significance of salt-tolerant matrix for the immobilization of nuclear wastes.