YU Xiaofeng1, ZHU Zhe1,2, GUO Xiangyu1, ZHANG Shuo1, SUN Zhiqiang1, SHEN Lie1

（1. School of Environmental Science and Safety Engineering, Tianjin University of Technology, Tianjin 300384, China;
2. Tianjin Key Laboratory of Hazardous Waste Safety Disposal and Recycling Technology, Tianjin 300384, China）

Abstract： In this study, Solanum nigrum that harvested from heavy metal contaminated site by Mn, Zn, Cr and Cd, was selected for the hydrothermal liquefaction (HTL) in isopropanol-water mixture to test the performance of bio-oil production and heavy metal distribution. The effect of isopropanol on product characteristics and migration-transformation of heavy metals (Mn, Zn, Cr and Cd) was investigated, and the HTL mechanism was illustrated. The HTL products were analyzed through elemental analysis, GC-MS, FT-IR, ICP-OES and XRD. In addition, the synergistic effect between water and isopropanol was evaluated. The results showed that the highest bio-oil yield of 61.34% and lowest solid yield of 3.16% was achieved with 50% of isopropanol in water at 300 oC. Besides, the bio-oil mainly consisted of hydrocarbons. Most of the heavy metals were distributed in the solid phase when HTL was carried out in isopropanol solvent, which were existed in low-valent oxidation state or even elemental metal by FT-IR and XRD analysis. The addition of isopropanol promoted the complexation of heavy metals with oxygen-containing functional groups. This paper provides an important reference for the further study on the harmless treatment of heavy metal contaminated plants and improvement the properties of bio-oil.

Key words：solanum nigrum；heavy metals；isopropanol；liquefaction

EARTH AND ENVIRONMENT Vol.51, No.4, Tot No.354, 2023, Page 412