Application of iron/aluminum bimetallic nanoparticle system for chromium-contaminated groundwater remediation

Jiun Hau Ou, Yih Terng Sheu, Daniel C.W. Tsang, Yong Jun Sun, Chih Ming Kao

Research output: Journal article publicationJournal articleAcademic researchpeer-review

37 Citations (Scopus)


When the nanoscale zero valent iron (nZVI) is used for the reduction of hexavalent chromium (Cr6+) to trivalent chromium (Cr3+) in groundwater, the reduction efficiency is decreased due to the passivation of reactive sites by precipitation. The bimetallic nanoparticle (BNP) can be created with the addition of the second metal to achieve a higher activity and reduce the occurrence of the ferrous/ferric hydroxide precipitation. In this study, the iron-coated aluminum (Fe/Al) BNP and aluminum-coated iron (Al/Fe) BNP systems were designed for remediating Cr6+-contaminated groundwater. The chemical liquid-phase deposition and co-reduction method was applied to produce BNPs. Cr6+ removal rate by Fe/Al BNPs was directly proportional to the saturation concentration and reactive sites, which caused a higher Cr6+ removal rate. The pseudo-first-order kinetic model could be used to describe the Cr6+ adsorption mechanism by Fe/Al BNPs. Results show that Fe/Al BNPs and Al/Fe BNPs could reduce Cr6+ to Cr3+, and the removal efficiencies for Cr6+ were 1.47 g/g BNP and 0.07 g/g BNP, respectively. Detection of Cr3+ in the aqueous phase was observed during the Cr6+ removal process. Results from X-ray diffraction (XRD) analysis confirmed that Cr(OH)3 was present on the surface of BNPs. Main mechanisms caused Cr6+ removal included reduction, precipitation, and adsorption. The reduction of Cr6+ produced OH, which created alkaline environment and facilitated the formation of chromium hydroxide precipitates [Cr(OH)3]. Thus, the migration of Cr3+ was prevented and the environmental risk was reduced. BNP had a higher activity and stability, and it was applicable for Cr6+-contaminated site remediation.

Original languageEnglish
Article number127158
Publication statusPublished - Oct 2020


  • Bimetallic nanoparticle (BNP)
  • Groundwater contamination
  • Hexavalent chromium (Cr)
  • Nanoscale zero valent iron (nZVI)
  • Site remediations

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Chemistry(all)
  • Pollution
  • Health, Toxicology and Mutagenesis


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