Enhancement of Zinc Ion Removal from Water by Physically Mixed Particles of Iron/Iron Sulfide

Yuya Kamba, Miharu Ueta, Md Azhar Uddin, Yoshiei Kato

Research output: Contribution to journalArticlepeer-review

Abstract

Zinc (Zn) removal by physically mixed particles of zero-valent iron (Fe) and iron sulfide (FeS) was investigated as one technology for Zn removal from waste groundwater. The effects of the Fe/FeS mass ratio, including a single Fe and FeS particles, and pH on changes in the concentrations of Zn, Fe, and S were examined by a batch test and column tests, and the mechanism of Zn elimination was discussed. Among all the mixing fractions of Fe and FeS, Zn was eliminated most effectively by 3Fe/7FeS (mass ratio of Fe/FeS = 3/7). The Zn removal rate decreased in the order of 3Fe/7FeS, FeS, and Fe, whereas the Fe concentration decreased in the order of Fe, FeS, and 3Fe/7FeS. The S concentration of FeS was larger than that of 3Fe/7FeS. The Zn removal rate by physically mixed 3Fe/7FeS particles was enhanced by a local cell reaction between the Fe and FeS particles. The electrons caused by Fe corrosion moved to the FeS surface and reduced the dissolved oxygen in the solution. Zn2+, Fe2+, and OH ions in the solution were then coprecipitated on the particles as ZnFe2(OH)6 and oxidized to ZnFe2O4. Moreover, Zn2+ was sulfurized as ZnS by both the Fe/FeS mixture and the simple FeS particles. The Zn removal rate increased with increasing pH in the range from pH 3 to 7. From a kinetic analysis of Zn removal, the rate constant of anode (Fe)/cathode (FeS) reaction was almost the same as that of ZnS formation and slightly larger than that of Fe alone.

Original languageEnglish
Article number17
JournalWater, Air, and Soil Pollution
Volume232
Issue number1
DOIs
Publication statusPublished - Jan 2021

Keywords

  • Groundwater treatment
  • Iron sulfide
  • Zero-valent iron
  • Zinc ion
  • Zinc removal

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Ecological Modelling
  • Water Science and Technology
  • Pollution

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