Experimental study on treatment of mixed ion exchange resins by supercritical water gasification

• Published in: Journal of cleaner production 2023-01, Vol.385, p.135755, Article 135755
• Main Authors: Wang, Le, Chen, Jia, Cui, Jinhua, Wang, Gaoyun, Jin, Hui, Guo, Liejin
• Format: Article
• Language: English
• Subjects: batch systems; benzene; carbon; Carbon gasification efficiency; catalysts; energy; ethylbenzene; gasification; Gasification mechanism; ion exchange; liquids; Mixed ion exchange resins; naphthalene; nitrogen; nuclear power; radioactive waste; styrene; sulfur; Supercritical water gasification; temperature; toluene; trimethylamine; xylene
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2022.135755

Nuclear power acts as a significant role in the current world energy supply system. The treatment of radioactive waste from nuclear station is a considerable issue and has attracted more and more attention. Spent ion exchange resins used in nuclear power plants are typical organic nuclear waste which are difficult to deal with. Supercritical water gasification could offer an efficient and clean treatment to spent ion exchange resins. In this study, Supercritical water gasification of mixed ion exchange resins was carried out in a batch reactor with various conditions. Effects of reaction parameters such as temperatures (550oC–750 °C), concentrations (5 wt%-15 wt%), catalysts (K2CO3, Na2CO3, KOH and NaOH) and residence times (10 min–60 min) were investigated. Results showed that high temperature, low concentration, K2CO3 addition and long residence time promote the gasification result. And the carbon gasification efficiency reached up to 97.2% with 10 wt% concentration and K2CO3 catalyst addition at 750 °C. The main intermediate organic component residues in liquid products were trimethylamine, benzene, toluene, ethylbenzene p-xylene styrene benzene, 1-ethyl-4-methyl- and naphthalene. Reaction pathways in supercritical water have been discussed and proposed. And the conversion pathways and distributions of sulfur and nitrogen were disclosed. [Display omitted] •Gasification of mixed ion exchange resins in supercritical water was studied.•The carbon gasification efficiency was up to 97.2% with 60 min at 750 °C.•The reaction pathway and mechanism of organic skeleton structure and functional group were disclosed.