Reuse of heavy metal-accumulating Cynondon dactylon in remediation of water contaminated by heavy metals

Phytoremediation technology is regarded as a simple and efficient way to remove heavy metals from contaminated soil. A reasonable disposal of metal hyperaccumulators is always a major issue in waste reuse and resource-saving. The heavy metal-accumulating Cynondon dactylon (L.) was investigated where heavy metals were desorbed by a facile acid-treatment. The result indicated that more than 90% of heavy metals (Zn, Pb and Cu) was extracted from Cynondon dactylon with 0.2 mmol ·L −1 HCl. The plant residue was used to adsorb heavy metals ions. The adsorption fitted the Langmuir isotherm model with the saturation adsorption capacity of 9.5 mg ·g −1 Zn 2+ , 36.2 mg·g −1 Pb 2+ and 12.9 mg·g −1 Cu 2+ , and the surface complexation and the backfilling of heavy metal-imprinting cavities existed simultaneously during the adsorption. The treatment of wastewaters indicated that the plant residue exhibited a high removal rate of 97% for Cu. Also, the material could be recycled. The method offers a new disposal approach for heavy metal hyper-accumulator.