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 languageEnglish
Article number104814
JournalProgress in Nuclear Energy
StatePublished - 1 Sep 2023


  • Cesium
  • Geochemical modelling
  • Geopolymers
  • Nitrate wastes

ASJC Scopus subject areas

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


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