Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Provincial Key Laboratory of Agricultural & Rural Pollution Abatement and Environmental Safety, College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China.
Université de Lorraine, INRAE, LSE, F-54000, Nancy, France.
J Environ Manage. 2024 Aug;366:121751. doi: 10.1016/j.jenvman.2024.121751. Epub 2024 Jul 6.
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.
热解是一种处理废弃矿山植物修复残渣的有效方法，可产生有价值的副产品——生物炭。然而，由于重金属带来的潜在环境风险，这类残渣制成的生物炭在环境中的应用受到限制。本研究以废弃矿山芒草为原料，在不同热解温度（300-700°C）下将其热解为生物炭，以促进植物修复残渣的安全再利用。结果表明，热解可显著稳定生物质中的重金属，其中 Cd 的稳定效果最为显著。在 700°C 时，Cd 的酸溶/可交换态和可还原态含量分别从 69.91%显著下降至 2.52%，而可氧化态和残渣态含量增加了约 3.24 倍。环境风险评估表明，热解温度高于 500°C 的生物炭环境风险较低（RI<30），更适合安全利用植物修复残渣。此外，吸附实验表明，高温（500-700°C）制备的生物炭具有更好的吸附能力，这归因于其碱性和沉淀作用。本研究表明，热解废弃矿山芒草制备的生物炭在 500°C 以上有望用于环境修复，为富金属生物质的再利用提供了新的思路。
