Both within the United States and internationally, hexavalent chromium or Cr(VI) is a contaminant of concern in drinking water supplies. The U.S. Environmental Protection Agency is considering a Cr(VI)-specific standard and California recently established a state drinking water standard for Cr(VI) of 10 µg/L. Thus improved technologies for Cr(VI) removal in drinking water are needed. Iron electrocoagulation (EC) is a technology that can successfully achieve low concentrations of Cr(VI) in treated drinking water.  In our research we have applied EC with iron serving as the sacrificial anode to treat simulated drinking water solutions.  Experiments have evaluated the effects of pH, dissolved oxygen, and voltage on Cr(VI) removal during batch EC treatment. Cr(VI) removal was faster with increasing pH because the reaction rate between Cr(VI) and Fe(II) increased with increasing pH from 4 to 8. Cr(VI) removal was also faster at higher applied voltages because more Fe(II) was generated for the same total reaction time.  Dissolved oxygen had almost no influence on Cr(VI) removal because Fe(II) reacts with O<sub>2</sub> much more slowly than it does with Cr(VI) at this pH. Fe(III) oxyhydroxides generated from Fe(II) oxidation when Cr(VI) is reduced in EC could accelerate Cr(VI) removal because heterogeneous reduction is faster than homogeneous reaction.<br/>

Hexavalent chromium removal by electrocoagulation in drinking water system

249th National Meeting (2015)

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