Removal of manganese(II) and iron(II) from synthetic groundwater using potassium permanganate

ABSTRACT

The removal of Mn²⁺ and Fe²⁺ from synthetic groundwater via oxidation using potassium permanganate was investigated. Batch jar tests were carried out under a constant pH of 8.0, where the effect of parameters such as the oxidant dose, presence of co-ions (Ca²⁺, Mg²⁺) and alum addition on the removal of Mn²⁺ and Fe²⁺ was examined. The partial removal of Mn²⁺ using aeration in single and dual metal system was 30.6% and 37.2%, respectively. The oxidant dose of 0.603 mg/L KMnO₄ was the minimum amount needed to reduce Mn²⁺ below its maximum contaminant level. The presence of Fe²⁺ improved the removal of Mn²⁺ due to the autocatalytic effect of hydrous manganese-iron oxide, where its presence was confirmed by digital microscopy and EDX. The presence of Ca²⁺ and Mg²⁺ as well as the alum addition after oxidation has a negative effect on the removal of Mn²⁺. The removal mechanism of Mn²⁺ and Fe²⁺ was a combination of oxidation and adsorption or co-precipitation between the hydrous oxide and the dissolved metal ions.

Keywords:

• Iron
• Manganese
• Groundwater
• Oxidation
• Potassium permanganate

Acknowledgments

This research was financially supported by Taiwan Water Cooperation (Taiwan), Udon Thani Rajabhat University (Thailand) and Suranaree University of Technology (Thailand).