Comparison of Powdered and PVC-Bound Todorokite Media for Heavy Metal Removal from Acid Mine Drainage Tailings

Acid mine drainage (AMD) is a prevalent danger to the environment as it contains high concentration of heavy metals at an acidic pH. Conventional treatment methodologies, such as lime neutralization, are an effective tool to raise the pH and significantly reduce the heavy metal concentration. However, solvated manganese is difficult to remove due to its high stability at alkaline pH, and conventional media treatment options for Mn(II) may not be appropriate for AMD. The need arises for an effective Mn(II) removal process from lime-treated AMD. This work investigates the preparation and applicability of poly(vinyl chloride) bound todorokite (PVC-T) beads as a means to scrub high Mn(II) concentration from lime neutralized AMD. While demonstrating lowered exchange kinetics due to mesoporous surface pores, the PVC-T suffered no capacity reduction when compared to the free todorokite powder (11 mg/g compared to 13 mg/g). Moreover, they were found to remove significant quantities of Mn(II) from lime neutralized AMD in a fixed bed column at a capacity of 7.76 mg/g. The PVC-T beads also markedly outperformed conventional greensands treatment and showed further capacity for Zn(II) and Co(II) removal. This work indicated that producing PVC/todorokite granules is an effective means of utilizing free powders in a fixed bed column to remedy real world environmental hazards.