A novel composite of layered double hydroxide/geopolymer for co-immobilization of Cs+ and SeO4 2− from aqueous solution

Quanzhi Tian, K. Sasaki

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

Geopolymers are always considered as promising materials for the treatment of radioactive wastes. In order to extend the application of geopolymer to the immobilization of anionic species, a novel composite of layered double hydroxide/geopolymer (LDH/GEO) was synthesized and applied for cosorption of Cs+ and SeO4 2−. The ability of LDH/GEO to sorb Cs+ was maintained as that of pure GEO, even though the surface of geopolymer was homogeneously covered by the LDH platelets. The sorption of Cs+ onto LDH/GEO composite occurred via ion exchange, which was controlled by particle diffusion. It is different with Cs+ sorption onto pure GEO governed by film diffusion. Therefore, “Pocket diffusion” was proposed for the particle diffusion as the case of LDH/GEO because this kind of diffusion would be restricted in a certain distance around the ring entrance gate due to the amorphous essence of GEO. For SeO4 2− sorption by LDH/GEO, ion-exchange with the interlayer NO3 and surface sorption could be the main mechanisms. Importantly, the sorption speed of SeO4 2− achieved by LDH/GEO composite was much faster than that by pure LDH. In the binary system (Cs++ SeO4 2−), the sorption of Cs+ was slightly suppressed compared to the single system, which might be due to the formation of ion-pair complex of [CsSeO4]. However, it did not have negative effect on the SeO4 2− sorption. In the presence of other cations or anions, the cosorption performances of Cs+ and SeO4 2− were satisfactorily obtained. Furthermore, the Cs+ and SeO4 2- sorption densities were superior to the previously reported values. The combined MgAl-LDH/geopolymer composite could be a promising material for the immobilization of Cs+ and SeO4 2−, and this work would provide guidance for the development of geopolymer-based materials for environmental applications.

Original languageEnglish
Article number133799
JournalScience of the Total Environment
Volume695
DOIs
Publication statusPublished - Dec 10 2019

All Science Journal Classification (ASJC) codes

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution

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