Performance study of ion exchange resins solidification using metakaolin-based geopolymer binder

Abstract

In this work, a laboratory study was conducted to assess the solidification feasibility of spent ion exchange resins from Taiwan Research Reactor by using geopolymer technology. Geopolymer has many superior properties to encapsulate spent ion exchange resins. The solidification of ion exchange resins (NRW100 cationic resin) into geopolymer binder was prepared with metakaolin and sodium alkaline solution at room temperature. The development of geopolymer formulation was prepared using various SiO2/Na2O molar ratios and different blast furnace slag content in metakaolin reagent. The physical properties such as workability and compressive strength were investigated. It indicated that geopolymer should choices with good balance of compressive strength and workability. Various amounts of ion exchange resins loading ranging from 6, 12 to 18 wt% (wet base) within the geopolymer were performed. The results indicate the loading ratio of ion exchange resin up to 12 wt% (wet base) by geopolymer binder was practicable. The compressive strength of the sample was greater than 139 kgf/cm2 after 28 days curing time. The leachability of the imitating ions was tested to evaluate the solidification performance of geopolymer binders. The leaching indexes of Cs+ and Sr2+ ions were greater than 10 that indicated the low leachability of both according to the ANSI/ANS 16.1 test. All test results including compressive strengths and leaching indexes met the criteria of regulation act in Taiwan. These results suggest that this metakaolin-based geopolymer formulation is a potential material for the solidification of spent ion exchange resins. In additionally leaching test, it had been proven that ion exchange resins without solidify release more radionuclides in contact with sodium chloride solution.