Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510006, China; Faculty of Engineering and Natural Sciences, Tampere University, Tampere, Finland.
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510006, China.
J Hazard Mater. 2021 May 15;410:124588. doi: 10.1016/j.jhazmat.2020.124588. Epub 2020 Nov 14.
Environmentally sound disposal of hyperaccumulator harvests is of critical importance to industrialization of phytoremediation. Herein, transformation behaviors and environmental risk of heavy metals were comprehensively examined during subcritical hydrothermal liquefaction of Sedum plumbizincicola. It is concluded that low temperature liquefaction favored resource recovery of heavy oil and hydrochars in terms of higher energy density, improved carbon sequestration and less energy consumption. Heavy metals were mainly distributed into hydrochars and water soluble phase with less than 10% in heavy oil. All metal elements except As could be accumulated in hydrochars by extending reaction time, whereas more than 96% of As was redistributed into water soluble phase. Prolonged liquefaction time facilitated immobilization of Cd, Cr and As in hydrochars, but fast liquefaction favored Pb stabilization. Liquefaction significantly reduced environmental risk level of Cd, Zn and As, but may mobilize Pb and Mn, especially for Mn to very high risk level at 240 ºC. High temperature with long reaction time tended to inhibit leaching rate of Mn, whereas low liquefaction temperature with short reaction time prevented the leaching of Zn and As from hydrochars. Overall, these findings are essential for downstream upgrading of heavy oil and metals recovery from hydrochars.
为实现植物修复的产业化，妥善处理超富集植物收获物至关重要。在此，通过亚临界水热液化对垂盆草进行了全面的转化行为和重金属环境风险研究。研究结果表明，低温液化有利于重油和水热炭的资源回收，因为其具有更高的能量密度、改善的碳固存和更少的能耗。重金属主要分布在水热炭和水可溶相中，重油中含量不到 10%。除了 As 之外，所有金属元素都可以通过延长反应时间而积累在水热炭中，而超过 96%的 As 则重新分配到水可溶相中。延长液化时间有利于 Cd、Cr 和 As 在水热炭中的固定，但快速液化有利于 Pb 的稳定。液化显著降低了 Cd、Zn 和 As 的环境风险水平，但可能会使 Pb 和 Mn 发生迁移，尤其是 Mn 在 240°C 时迁移到很高的风险水平。高温和长时间的反应时间往往会抑制 Mn 的浸出率，而低温和短时间的反应时间可以防止 Zn 和 As 从水热炭中浸出。总的来说，这些发现对于重油的下游升级和从水热炭中回收金属都很重要。
