ENVR 144 |
| Acid mine drainage (AMD), usually generated from mine sites, contains elevated levels of toxic heavy metals, which can have an adverse impact to the surrounding environment. The major pathway involved in generation of AMD is weathering of pyritic mineral ores, where sulfur is oxidized to sulfate followed by the release of metal ions. Due to the low pH of the AMD, the metals are present in the dissolved phase and are, therefore, highly active and more mobile. Increased awareness of heavy metal toxicity and extent of contamination throughout the country have stimulated the regulators to investigate treatment processes which can remove heavy metals present in the surface water including mine drainage. In this study, we report the mechanisms of toxic heavy metal removal from acid mine drainage using chitin as a biosorbent. Chitin, obtained from exoskeletons of crabs and other arthropods, is regarded as cellulose with a N-acetyl group. Due to its behavior of forming stable metal complexes, chitin is an excellent physical sorbent, especially at low pH. Chitin also retains its permeability during degradation, making it an excellent candidate for use in AMD remediation. Batch adsorption experiments on AMD removal using chitin were performed. Heavy metals reached equilibrium within 24 h, with more than 90% metal removal. The effect of pH, sorbent loading and addition of manure was also investigated. The mechanisms for the removal of free heavy metal ions by chitin was based mainly on the complexation adsorption model, as well as an affinity of hydroxyl groups of the materials on metals. |
|
General Papers
6:00 PM-8:00 PM, Wednesday, August 22, 2007 BCEC -- Exhibit Hall - B2, Poster
Division of Environmental Chemistry |