In this study, the geopolymer from fly ash as based-raw material has been examined on the ability of immobilization of several heavy metal ions. The fly ash analyzed for its physical and chemical properties. Fly ash and heavy metals were then mixed with an activator base until being homogeneous prior to be cast into a cylindrical mold following ASTM C 39-86 and left for 7 days. Subsequently, the geopolymer was characterized by SEM, FTIR, XRD, compressive strength test and toxicity characteristic leaching procedure (TCLP). The diffractogram of fly ash exhibited the existence of mullite, alumina and iron oxide phase, which were suitable with XRF result. From FTIR spectra, the vibration on finger print area appeared indicating the vibration of T-O-T from geopolymer network. The observation revealed that the addition of Pb2+ cations caused microcracking from SEM image and affected the compressive strength of the geopolymer. Sr2+ was an ion that was very easily leached compared to other three ions, and it caused a weak interaction between Sr2+ and geopolymer network. The higher amount of metal ions into the geopolymer network reduced the compressive strength of geopolymer.

Original languageEnglish
Pages (from-to)112-118
Number of pages7
JournalCommunications in Science and Technology
Issue number2
Publication statusPublished - 2022


  • Fly ash
  • environmentally sound technologies
  • geopolymer
  • immobilization


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