Environmental remediation potential of a pioneer plant (Miscanthus sp.) from abandoned mine into biochar: Heavy metal stabilization and environmental application

• Published in: Journal of environmental management Vol. 366; p. 121751
• Main Authors: Li, Xiao, Lin, Shukun, Ouvrard, Stephanie, Sirguey, Catherine, Qiu, Rongliang, Wu, Bohan
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.08.2024
• Subjects: Adsorption; Environment risk; Heavy metals; Phytoremediation residue; Pyrolysis; Pyrolysis; Environment risk; Adsorption; Heavy metals; Phytoremediation residue
• ISSN: 0301-4797; 1095-8630; 1095-8630
• DOI: 10.1016/j.jenvman.2024.121751

Pyrolysis stands out as an effective method for the disposal of phytoremediation residues in abandoned mines, yielding a valuable by-product, biochar. However, the environmental application of biochar derived from such residues is limited by the potential environmental risks of heavy metals. Herein, Miscanthus sp. residues from abandoned mines were pyrolyzed into biochars at varied pyrolysis temperatures (300–700 °C) to facilitate the safe reuse of phytoremediation residues. The results showed that pyrolysis significantly stabilizes heavy metals in biomass, with Cd exhibiting the most notable stabilization effect. Acid-soluble/exchangeable and reducible fractions of Cd decreased significantly from 69.91 % to 2.52 %, and oxidizable and residue fractions increased approximately 3.24 times at 700 °C. The environmental risk assessment indicated that biochar pyrolyzed over 500 °C pose lower environmental risk (RI < 30), making them optimal for the safe utilization of phytoremediation residues. Additionally, adsorption experiments suggested that biochars prepared at higher temperature (500–700 °C) exhibit superior adsorption capacity, attributed to alkalinity and precipitation effect. This study highlights that biochars produced by pyrolyzing Miscanthus sp. from abandoned mines above 500 °C hold promise for environmental remediation, offering novel insight into the reutilization of metal-rich biomass. [Display omitted] •Heavy metals in Miscanthus sp. obtained from abandoned mines could be stabilized after pyrolysis.•The environment risk of heavy metals in biochars generated above 500 °C were low.•Higher pyrolysis temperature could achieve better Cd2+ adsorption capacity of biochars.•500–700 °C were suitable for the safe reutilization of phytoremediation residues.