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

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% KMnO 4 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