Investigating the role of sodium persulfate as a hydroxyl radical initiator in Catalyzing zeolite synthesis from fly ash

Dingcheng Liang*, Qingping Chen, Ruicong Zhang, Qiang Xie, Mengyuan Zhu, Guangbo Liu, Yutong Wang, Yang Song, Zhijun Zhang, Fei Xie, Jinchang Liu, Zhucan Xie, Xiao Yang, Noritatsu Tsubaki*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Sodium persulfate (Na2S2O8) was employed as an initiator to enhance the depolymerization and dissolving of fly ash and to direct rearrangement of dissolved silicon-aluminum to construct high quality zeolite through the generation of hydroxyl radicals (•OH). The results demonstrated that Na2S2O8 effectively generated •OH in the alkaline fly ash synthesis system, with the amount of •OH produced increasing proportionally to the concentration of Na2S2O8. Furthermore, the introduction of •OH reduced the synthesis time by 12 h and accelerated the formation of pore fractals during the zeolite synthesis from fly ash by an additional 12 h. The average size of the synthesized NaP zeolite decreased from 283.81 to 164.95 nm, the interlayer distance decreased from 0.55 nm to 0.34 nm, the surface area increased from 34.23 to 41.77 m2/g, and the silicon-to-aluminium ratio increased from 1.08 to 1.51, yielding a higher-quality zeolite product within a shorter synthesis period. In addition, theoretical calculations indicated that the reaction pathway for •OH-catalyzed depolymerization of inert silicon-aluminium is similar to that of hydroxide ions (OH). The energy barrier for the depolymerization reaction with the participation of •OH was 3.29 kcal/mol, which is lower than the 3.43 kcal/mol required for OH. Consequently, •OH demonstrated a more pronounced catalytic effect on the depolymerization of inert silicon-aluminium species compared to OH, and •OH significantly reduced the required alkalinity for the synthesis system, thereby optimizing the conditions for zeolitization of fly ash. This study will provide valuable insights for the future design and synthesis of nanomaterial from fly ash.

Original languageEnglish
Article number160714
JournalChemical Engineering Journal
Volume507
DOIs
StatePublished - 2025/03/01

Keywords

  • Fly ash
  • Hydroxyl radicals
  • Reaction pathway
  • Sodium persulfate
  • Zeolite

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry
  • General Chemical Engineering
  • Industrial and Manufacturing Engineering

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