Removal of Cr(VI) from Cr-contaminated groundwater through electrochemical addition of Fe(II)

J Environ Manage. 2007 Jan;82(1):66-76. doi: 10.1016/j.jenvman.2005.12.005. Epub 2006 Mar 20.

Abstract

The conventional chemical reduction-precipitation technique in the removal of Cr(VI) from contaminated groundwater involves a two-step process whereby Cr(VI) is first reduced to Cr(III) at an acidic pH by a reducing agent and in a subsequent step, Cr(III) is precipitated as insoluble hydroxide at an alkaline pH. In a variation of this method, Fe(II) is added electrochemically to the Cr(VI) containing water. From a pure iron electrode, Fe(2+) ions are released into the solution and bring forth the reduction of Cr(VI). At the cathode, H(2)O is reduced whereby the OH(-) ions entering the solution keep the pH of the solution in the alkaline range. This latter fact greatly facilitates simultaneous reduction of Cr(VI) to Cr(III) and co-precipitation of hydroxides of trivalent Cr and Fe. On the basis of a set of experimental data, it is shown that this process is both thermodynamically and kinetically efficient, meaning, with the electrochemical method, rapid and nearly complete removal of Cr(VI) from a groundwater source with both high and low levels of Cr-contamination can be achieved. These factors make the electrochemical process superior to the conventional chemical process in remediation of Cr-contaminated groundwater.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cations, Divalent
  • Chromium / isolation & purification*
  • Electrochemistry
  • Electrodes
  • Geography
  • Hydrogen-Ion Concentration
  • Industrial Waste
  • Iron / chemistry*
  • Kinetics
  • Thermodynamics
  • Waste Disposal, Fluid / methods*
  • Water Pollutants, Chemical / isolation & purification*
  • Water Supply*

Substances

  • Cations, Divalent
  • Industrial Waste
  • Water Pollutants, Chemical
  • Chromium
  • chromium hexavalent ion
  • Iron