Fu Haiying, Wang Shuai, Zhang Hui, Dai Zhongran, He Guicheng, Li Guangyue, Ding Dexin
Key Discipline Laboratory for National Defense for Biotechnology in Uranium Mining and Hydrometallurgy, University of South China, Hengyang, 421001, People's Republic of China.
School of Resource Environment and Safety Engineering, University of South China, Hengyang, 421001, People's Republic of China.
Environ Sci Pollut Res Int. 2022 Nov;29(51):77839-77850. doi: 10.1007/s11356-022-20704-1. Epub 2022 Jun 10.
Uranium (U) in the U-contaminated acidic red soil exhibits high mobility. In the present study, rice husk was used to produce biochar to remediate U-contaminated red soil under acid precipitation. Firstly, batch adsorption experiments showed that the dissolution of alkaline substance in biochar could buffer the pH value of acidic solution. The equilibrium pH value had a crucial influence on biochar adsorption capacity of U, and the neutral equilibrium pH value was favorable for adsorption. Then, the incubation experiments of red soil with biochar were performed, and the Synthetic Precipitation Leaching Procedure (SPLP) extraction of amended red soil showed that the short-term leachability of U was decreased from 26.53% in control group (without biochar) to 1.40% in 10% biochar-amended red soil. Subsequently, the sequential extraction showed that the fraction of U was mainly transformed from exchangeable and Fe/Mn oxide fraction to carbonate fraction after biochar amendment, and the total amount of exchangeable U and carbonate fraction U in soil was increased slightly. Finally, simulated acid rain leaching experiments showed that the capability of amended red soil to resist acid rain acidification was enhanced. And the long-term leachability of U in amended red soil was decreased from 26.37% in control group to 3.18% in the 10% biochar-amended red soil under the simulated acid rain leaching conditions. In conclusion, biochar has passivation effect on U in U-contaminated red soil, which can reduce the long-term and short-term mobility of U in acidic environments. This study provided an experimental basis for the application of biochar in remediation and improvement of U-contaminated acidic red soil.
铀污染酸性红壤中的铀具有高迁移性。在本研究中，稻壳被用于制备生物炭，以修复酸性降水条件下铀污染的红壤。首先，批次吸附实验表明，生物炭中碱性物质的溶解可缓冲酸性溶液的pH值。平衡pH值对生物炭对铀的吸附能力有至关重要的影响，中性平衡pH值有利于吸附。然后，进行了红壤与生物炭的培养实验，改良红壤的合成沉淀浸出程序（SPLP）提取结果表明，铀的短期浸出率从对照组（无生物炭）的26.53%降至10%生物炭改良红壤中的1.40%。随后，连续提取表明，生物炭改良后，铀的形态主要从可交换态和铁/锰氧化物态转化为碳酸盐态，土壤中可交换态铀和碳酸盐态铀的总量略有增加。最后，模拟酸雨淋溶实验表明，改良红壤抵抗酸雨酸化的能力增强。在模拟酸雨淋溶条件下，改良红壤中铀的长期浸出率从对照组的26.37%降至10%生物炭改良红壤中的3.18%。总之，生物炭对铀污染红壤中的铀具有钝化作用，可降低铀在酸性环境中的长期和短期迁移性。本研究为生物炭在铀污染酸性红壤修复和改良中的应用提供了实验依据。
