[2B08-11] Geopolymer 2 and Alkali Activated Material

[2B09] Cs⁺, Sr²⁺ and Co²⁺ uptake in metakaolin-based geopolymer

*Yogarajah Elakneswaran¹, Xiaobo Niu¹, Yuka Morinaga¹, John Provis², Tsutomu Sato¹ (1. Hokkaido University, 2. The University of Sheffield)

Keywords:Adsorption, Ionic exchange, Zeta potential, Geochemical model

In this study, the interaction of Cs⁺, Sr²⁺ and Co²⁺ with Na/K-geopolymer is investigated. The geopolymer samples with the composition of SiO₂/K₂O: Al₂O₃/K₂O: H₂O/K₂O = 1:1:11 (where K: Na or K) were synthesised for the experiments, and the surface electrostatic characteristics of the geopolymer is examined by zeta potential measurement. The zeta potential experimental results show that Sr²⁺ and Co²⁺ can be adsorbed on the surface of the geopolymer, but not Cs⁺. The ion-exchange with Na⁺/K⁺ is the main mechanism for the Cs⁺ incorporation into the geopolymer. An ion-exchange model is developed in a geochemical code PHREEQC to predict the adsorption behaviour of Cs⁺ and the modelling results predict satisfactorily the experimental data.