An investigation of Cr(VI) removal with metallic iron in the co-presence of sand and/or MnO2

J Environ Manage. 2016 Apr 1:170:145-51. doi: 10.1016/j.jenvman.2016.01.013. Epub 2016 Jan 27.

Abstract

This study focused on the influence of sand and/or MnO2 co-presence on the mechanism and kinetics of Cr(VI) removal with Fe(0). The process was investigated under acidic and well-mixed conditions, over the temperature range of 6-32 °C. It was shown that both mechanism and kinetics of the removal process were highly dependent on composition and dose of reactive mixture added to Cr(VI) solution. At 22 °C, indirect chemical reduction with Fe(II) was the main removal path in H2O-Fe(0)-Cr(VI) and H2O-Fe(0)-Sand-Cr(VI) system, while in H2O-Fe(0)-MnO2-Cr(VI) and H2O-Fe(0)-MnO2-Sand-Cr(VI) system removal of Cr(VI) occurred mainly via adsorption on MnO2. The pseudo zero-order kinetic model provided the best match for H2O-Fe(0)-Cr(VI) and H2O-Fe(0)-Sand-Cr(VI) system, while in H2O-Fe(0)-MnO2-Cr(VI) and H2O-Fe(0)-MnO2-Sand-Cr(VI) system the process fitted well to the pseudo second-order model. Temperature influenced the efficiency and kinetics of the process in all investigated systems, and the removal mechanism only in H2O-Fe(0)-MnO2-Cr(VI) and H2O-Fe(0)-MnO2-Sand-Cr(VI) system.

Keywords: Hexavalent chromium; Manganese dioxide; Metallic iron; Sand; Water pollution.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adsorption
  • Chemical Phenomena
  • Chromium / chemistry*
  • Humans
  • Iron / chemistry*
  • Kinetics
  • Manganese Compounds / chemistry*
  • Oxides / chemistry*
  • Silicon Dioxide / chemistry
  • Water Pollution / prevention & control
  • Water Purification

Substances

  • Manganese Compounds
  • Oxides
  • Chromium
  • chromium hexavalent ion
  • Silicon Dioxide
  • Iron
  • manganese dioxide