pH-dependent Cs leaching from nitrate bearing geopolymers: A combined experimental and model analysis

Yonatan Harnik, Ofra Klein-BenDavid, Erez Boukobza, Ira A. Weinstock, Gabriela Bar-Nes

Research output: Contribution to journalArticlepeer-review


Geopolymers are considered as promising wasteforms for the immobilization of low-level radioactive waste streams containing 137Cs. This work presents an experimental study and modelling of the pH-dependent leaching of Cs from nitrate bearing geopolymers. Longer curing periods and higher curing temperatures induce the formation of nitrate bearing zeolitic phases (NO3-sodalite and NO3-cancrinite), that exhibit higher Cs/Na selectivity relative to nitrate-free zeolitic phases (zeolite A and zeolite X). Such phase formation was found to have a significant effect on the pH-dependent leaching of Cs, as well as on the leaching of other major elements in the geopolymeric system. An innovative, semi-empirical geochemical thermodynamic model was developed for the sodium aluminum silicate hydrate (NASH) solid solution, based on the pH-dependent leaching experimental data. The model succeeded to describe most of the studied system, with emphasis on their interaction with Cs.

Original languageAmerican English
Article number104814
JournalProgress in Nuclear Energy
StatePublished - 1 Sep 2023


  • Cesium
  • Geochemical modelling
  • Geopolymers
  • Nitrate wastes

All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Safety, Risk, Reliability and Quality
  • Energy Engineering and Power Technology
  • Waste Management and Disposal


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