分类： 核科学技术 >> 核材料与工艺技术 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
LAN Tu
DING Cong-Cong
LIAO Jia-Li
LI Xiao-Long
LI Xing-Liang
ZHANG Jie
ZHANG Dong
YANG Ji-Jun
LUO Shun-Zhong
AN Zhu
WU Qi-Qi
YANG Yuan-You
FENG Su
TANG Jun
LIU Ning
摘要： To develop a microbe-based bioremediation strategy for cleaning up thorium-contaminated sites, we have investigated the biosorption behavior and mechanism of thorium on Bacillus sp. dwc-2, one of the dominant species of bacterial groups isolated from soils in Southwest China. Thorium biosorption depended on the pH of environment, and its rapid biosorption reached a maximum of up to 10.75 mg Th per gram of the bacteria (wet wt.) at pH 3.0. The biosorption agreed bettter with Langmuir isotherm model than Freundlich model, indicating that thorium biosorption was a monolayer adsorption. The thermodynamic parameters, negative change in Gibbs free energy and positive value in enthalpy and entropy, suggested that the biosorption was spontaneous, more favorable at higher temperature and endothermic process with an increase of entropy. Scanning electron microscopy (SEM) indicated that thorium initially binded with the cell surface, while transmission electron microscopy (TEM) revealed that Th deposited in the cytoplasm and served as cores for growth of element precipitation (e.g., phosphate minerals) or by self-precipitation of hydroxides, which is probably controlled by ion-exchange, as evidenced by particle induced X-ray emission (PIXE) and enhanced proton backscattering spectrometry (EPBS). Fourier Transform Infrared (FTIR) further indicated that thorium biosorption involved carboxyl and phosphate groups and protein in complexation or electrostatic interaction. Overall results indicated that a combined electrostatic interaction-complexation-ion exchange mechanism could be involved in thorium biosorption by Bacillus sp. dwc-2.
分类： 核科学技术 >> 核材料与工艺技术 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
LIU Xiao-Qing
YANG Yuan-You
LIAO Jia-Li
OU Wei
KONG Fang
LAN Jing-Bo
LUO Shun-Zhong
LIU Guo-Ping
HE Jia-Heng
YANG Ji-Jun
TANG Jun
LIU Ning
摘要： Uranium removal efficacy of fullerence multi-macrocyclic polyamine derivatives (C60-MMP), a novel chelating agent, was evaluated in mice. C60-MMP was administrated intravenously into mice at 30 min after the uranium contamination. The molar ratio of chelating ligand/uranium was about 1:1. The results indicate that C60-MMP can effectively prevent accumulation of uranium in liver at 8 h after C60-MMP injection. At 48 h after the last injection, uranium deposition in liver of C60-MMP treated mice is approximately 65% less than that of the control group. C60-MMP reacted positively in promoting the removal of uranium from kidney, and the urinary uranium excretion increased significantly, compared with the control and DTPA-treated mice. However, repeated administration of C60-MMP, and combined injection of DTPA and C60-MMP, did not show desirable effects on uranium removal from mice. It implies that more investigations are needed for the treatment protocols and clinical applications of C60-MMP.
分类： 核科学技术 >> 核材料与工艺技术 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： The complexation, precipitation, and migration behavior of uranium in the presence of humic acid (HA) or fulvic acid (FA) were investigated by cation exchange, ultrafiltration and dynamic experiment, respectively. The results showed that (i) complex equilibrium between the uranium and humic substances was achieved at approximately 72 h, (ii) the coordination number varied from 1:1 to 1:2 ( U(VI) : humic acid) as pH increased from 3 to 6; and (iii) , while the complex stability constant decreased when temperature increased, but increased with pH value. We found that the precipitation of uranyl could only be observed in presence of HA, and the precipitation was influenced by conditions, such as pH, uranium concentration, temperature, and the HA concentration. The maximum precipitation proportion up to 60% could be achieved in the condition of 40 mg/L HA solution at pH 6. We further observed that the migration behavior of uranium in soil in the presence of humic acid (HA) or fulvic acid (FA) was different from that in the presence of inorganic colloid, and the effect of humic substances (HS) was limited.
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