Oyster shell powder for Pb(II) immobilization in both aquatic and sediment environments

Heavy metal pollution has always been a serious environmental problem widely concerned by researchers all around the world. On the other side, the accumulation of biowastes has also occupied a large amount of space and caused a series of environment pollution. In this study, the waste oyster shell, was applied as a type of biogenic carbonate material for Pb(II) removal from the aquatic environment, and further as a remediation agent for metal stabilization in the contaminated river sediment. After simple pretreatment, the oyster shell powder (OSP) was characterized, and the results showed that the prepared OSP is mainly composed of calcite with particle size of micron-level. The OSP exhibited excellent Pb(II) adsorption performance, with the adsorption capacity as 639.9 mg/g through adsorption isotherm study. Furthermore, the OSP was applied to remediate the collected river sediment artificially contaminated by Pb(II). It was found that the proportion of residual Pb fraction (F4) was greatly increased from 39.6% of the original sediment to 76.7% in the 14-day incubated sediment with OSP. The Pb(II) concentration after leaching procedure was decreased from 810.7 to 108.6 μg/L even after 5-day incubation. Therefore, this study shows the potential of using waste oyster shell as adsorbent and amendment agent for effective metal immobilization in both aquatic and sediment systems.