Uranium-stressed soil caused by nuclear industry development and energy acquisition have attracted extensive attentions for a long time. This study investigated the effects of biochar application with different pyrolysis temperatures (300 ℃, 500 ℃ and 700 ℃) on remediation of uranium-stressed soil. The results showed that higher pyrolysis temperature (700 ℃) was benefit for ryegrass growing and caused a lower uranium accumulation in plants. At the same time, uranium immobilization was more effective at higher biochar pyrolysis temperature. Careful investigations indicated that activities of soil urease and sucrase were promoted, and bacterial diversity was strengthened in C700 group, which may contribute to uranium immobilization. The biochar application could activate metabolic of lipids and amino acids , organic acids and derivatives, and organic oxygen compounds. Nicotinate and nicotinamide metabolism, and Benzoxazinoid biosynthesis were unique metabolic pathways in the C700 group, which could enhance the uranium tolerance from different perspectives. Based on these results, we recommend to use biochar with 700 °C pyrolysis temperature when processing remediation of uranium-stressed soil. This study will facilitate the implementation of biochar screening and provide theoretical helps for remediation of uranium-stressed soil.
Quan Chen,Xiangmei Cheng,ShengSheng Liu,Dichen Xia,Yan Liu,Zhen Zhang,Pengcheng Gu
Biochar materials with low cost and desired properties have gradually been widely applied in multitudinous domains, especially in radioactive wastewater remediation. Multi-heteroatom doping is a useful method for the design of doping biochar with uranium immobilization of excellent performance. Herein, multi-heteroatom self-doped microporous carbon was designed and synthesized via extraction and carbonization of collagen by potassium compound assisted, which was extracted by low-cost fish scales as the precursor and tested for high-performance uranium immobilization . The multi-heteroatom self-doped biochar exhibited the maximum saturated adsorption capacity of 142.06 mg/g for U(VI) at pH = 5, reflecting the significant increase in available adsorption sites from multi-heteroatom doped. The strong complexation process was proposed for the mutual effect between U(VI) and multi-heteroatom doped biochar, where abundant functional groups (oxygen and amino) and sulfur metal sites groups were the primary active sites. The design of multi-heteroatom self-doped biochar provided a universal and effective method for purifying U(VI) from wastewater systems.
Peng Lyu,Guanghui Wang,Yelin Cao,Bing Wang,Nansheng Deng
The decommissioning of uranium mill tailings (UMTs) is usually accompanied by uranium (U) contamination in soil, which poses a serious threat to human health and ecological safety. In this study, a novel phosphorus-modified bamboo biochar (PBC) cross-linked Mg–Al layered double-hydroxide (LDH) composite (“PBC@LDH”) was successfully prepared by phosphate pre-impregnation and a hydrothermal method with Mg–Al LDH. Physicochemical analysis revealed that phosphorus-containing functional groups and Mg–Al LDH were grafted onto the pristine biochar (BC) matrix. Laboratory-scale incubation and column leaching experiments were performed on the prepared BC, PBC, and PBC@LDH. The results showed that, at a dosage of 10%, the PBC@LDH composite had a commendable ability to immobilize U in soil. After 40 days of incubation with the stabilizer, the more mobile U was converted into immobilized species. Furthermore, during a column leaching experiment with simulated acid rain, the cumulative loss and leaching efficiency of U were remarkably reduced by PBC@LDH treatment compared with the control, reaching 53% and 54%, respectively. Surface complexation, co-precipitation, and reduction described the adsorption and immobilization mechanisms. In conclusion, this research demonstrates that the PBC@LDH composite offers a potentially effective amendment for the remediation of U contaminated soil.
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