Performance of phosphoric acid activated montmorillonite as buffer materials for radioactive waste repository

Tsing Hai Wang, Tsung Ying Liu, Ding Chiang Wu, Ming Hsu Li, Jiann Ruey Chen, Shi Ping Teng

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


In this study, the performance of phosphoric acid activated montmorillonite (PAmmt) was evaluated by cesium ions adsorption experiments. The PAmmt samples were obtained by activating with 1, 3 and 5 mol L-1 of phosphoric acid, respectively under reflux for 3, 12, and 24 h. Experimental results demonstrated that the treatment of raw K-10 montmorillonite with phosphoric acid increased the materials' affinity for Cs uptake and no significant amount of suspension solids were produced. A relatively insignificant variation in the CEC value was observed. Furthermore, PAmmt also showed high adsorption selectivity toward Cs ions. The improved sorptive properties were mainly related to the increased surface area and the relatively higher surface charge density. Increased specific surface area was the resulted from partial decomposition of lamellar structure of mmt; while the higher surface charge density was caused by the protonation of octahedral Al-OH sites during the acid activation. Generally speaking, stronger acid concentration and longer activation times would produce relatively more decomposed PAmmt particles. However, as the activation exceeds 3 h, the precipitation of Si4+ would passivate PAmmt against further acid attacks. Based upon our results, acid activation by phosphoric acid could produce PAmmt samples with high sorption capacity and selectivity, and good structural integrity, which are beneficial to be used at radioactive waste repository. Crown

Original languageEnglish
Pages (from-to)335-342
Number of pages8
JournalJournal of Hazardous Materials
Issue number1-3
StatePublished - 15 Jan 2010


  • Acid activation
  • Cesium
  • Montmorillonite
  • Radioactive waste repository
  • Safety assessment


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