Department of Environmental Science & Engineering, Hunan Agricultural University, Changsha 410128, China.
Department of Materials Science, Hunan Agricultural University, Changsha 410128, China.
Int J Environ Res Public Health. 2023 Jan 11;20(2):1311. doi: 10.3390/ijerph20021311.
The removal of heavy metals is crucial to the utilization of contaminated biomass resources. In this study, we report an efficient process of hydrothermal conversion (HTC) of sunflower straw ( L.) to remove heavy metals. The effect of different HTC temperatures and concentrations of HCl additives on heavy metal removal efficiency was investigated. The results revealed that increasing the temperature or concentration of HCl promoted the transfer of heavy metals from hydrochar to liquid products during HTC. The heavy metals removed to the liquid products included up to 99% of Zn and Cd, 94% of Cu, and 87% of Pb after hydrothermal conversion with a temperature of 200 °C and HCl 2%. The species of heavy metals in hydrochars converted from unstable to stable with an increase in temperature from 160 °C to 280 °C. The stable fractions of heavy metals in the acidic condition decreased as the acid concentration increased. This aligns well with the high transfer efficiency of heavy metals from the solid phase to the liquid phase under acidic conditions. The FTIR indicated that the carboxy and hydroxy groups decreased significantly as the temperature increased and the concentration of HCl increased, which promoted the degradation of sunflower straw. A scan electron microscope showed that the deepening of the destruction of the initial microstructure promotes the transfer of heavy metals from hydrochars to liquid phase products. This acid-assisted hydrothermal process is an efficient method to treat biomass containing heavy metals.
去除重金属对于利用受污染的生物质资源至关重要。在本研究中，我们报告了一种有效的向日葵秸秆（L.）水热转化（HTC）过程，用于去除重金属。研究了不同 HTC 温度和 HCl 添加剂浓度对重金属去除效率的影响。结果表明，在 HTC 过程中，升高温度或增加 HCl 浓度会促进重金属从水炭向液体产物转移。在 200°C 和 HCl 2%的条件下进行水热转化后，高达 99%的 Zn 和 Cd、94%的 Cu 和 87%的 Pb 被转移到液体产物中。随着温度从 160°C 升高到 280°C，水热转化得到的水炭中重金属的形态从不稳定向稳定转变。在酸性条件下，重金属的稳定分数随着酸浓度的增加而降低。这与在酸性条件下重金属从固相高效转移到液相的情况一致。FTIR 表明，随着温度升高和 HCl 浓度增加，羧基和羟基基团显著减少，促进了向日葵秸秆的降解。扫描电子显微镜显示，初始微观结构破坏程度的加深促进了重金属从水炭向液相产物的转移。这种酸辅助的水热工艺是处理含重金属生物质的有效方法。
