Elution characteristics of undesirable anionic species from fly ash blended cement in different aqueous solutions

Keiko Sasaki, Shingo Nakama, Quanzhi Tian, Binglin Guo, Mengmeng Wang, Ryoichi Takagi, Tomohiko Takahashi

Research output: Contribution to journalArticlepeer-review

Abstract

There are few reports to explore immobilization of undesirable anionic species released from fly ash (FA) blended cement. This study clarifies the stabilities of several undesirable anionic species, through dissolution tests under a different matrix. The immobilization mechanism mainly involves co-precipitation with ettringite and hydrocalumite, the marginal formation of insoluble Ca salts, and occlusion in calcium silicate hydrates and amorphous phases produced during the pozzolanic reaction. The products released some amounts of chromate, arsenate, and selenite but not borate in dissolution tests. Elution of borate was the most effectively immobilized by Ca additives, owing to selective incorporation in ettringite. Moreover, selenite showed a trend of dissolving in acidic conditions, presumably owing to the dissolution of CaSeO3 with relatively high Ksp in addition to coprecipitation with hydrocalumite and ettringite. Under the present mixing condition of cementation, only selenite is a cautionary species which excessively eluted over the environmental standard.

Original languageEnglish
Article number105171
JournalJournal of Environmental Chemical Engineering
Volume9
Issue number3
DOIs
Publication statusPublished - Jun 2021

All Science Journal Classification (ASJC) codes

  • Chemical Engineering (miscellaneous)
  • Waste Management and Disposal
  • Pollution
  • Process Chemistry and Technology

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