Manganese oxide coated river sand for Mn(II) removal from groundwater

Abstract

BACKGROUND High levels of soluble Mn(II) are often detected in groundwater in many countries, including the northeast region of China. It is necessary to remove excess amounts of Mn(II) from groundwater, especially in country sites, outside big cities. Coating manganese oxides onto a stable, cheap granular media provides an attractive alternative for Mn(II) removal from water. RESULTS Manganese oxide coated sand (MOCS) was prepared by base activation of sand with 9% NaOH for 24 h, soaking base activated sand with 7% KMnO4 for 24 h and finally calcination at 250 °C for 4 h. The MOCS had a significantly rougher surface and its surface was apparently coated with newly formed clusters of crystalline manganese oxide with a mixed manganese oxidation state of (Mn(III) and Mn(IV)). The manganese oxide effectively oxidized Mn(II) in the water to Mn(III) and Mn(IV). MOCS exhibited good Mn(II) removal performance in the filter bed experiment. The results suggested that a new catalytic flocculent manganese oxide layer was generated on the MOCS surface after filtration. CONCLUSION The new prepared MOCS in this study has potential as a catalytic adsorbent for Mn(II) removal in small waterworks in country sites. © 2014 Society of Chemical Industry