Copper(II) and lead(II) binding by alfalea biomass: use of chemical modification and x-ray absorption spectroscopy to determine the metal binding mechanism

摘要

Traditional methods currently employed to remediate heavy metal-contaminated waters prove to be cost prohibitive. Therefore, more-cost-effective methods of remediating heavy metals from contaminated waters need to be developed. Th use of plant materials as metal adsorbents may be a possible solution. Previously performed experiments have shown that alfalfa shoot biomass can bind an appreciable amount of heavy metal ions, even from multi-contaminate-containing solutions. Although alfalfa biomass has shown to be very effective at removing heavy metal ions from aqueous solution, more research is needed to understand the metal-binding mechanism. Carboxyl groups were chemically modified in order to determine their contribution to the metal-binding process. Batch experiments were performed with the modified biomass and suggest that carboxyl groups play a significant role in the binding of copper (II) and lead(II). In addition, X-ray absorption spectroscopic analysis (XANES and EXAFS) corroborates these results. These studies are important for determining the ligands that may be involved in the binding of copper and lead ions to alfalfa biomass, thus aiding ih our understanding of the mechanisms involved in the removal and recovery of metal ions from contaminated waters through phytofiltration.