期刊：
JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY,2014年299(3):1903-1909 ISSN：0236-5731
通讯作者：
Ding, DX
作者机构：
[Fu, Pingkun; Xin, Xin; Hu, Nan; Li, Guangyue; Ding, Dexin] Univ South China, Key Discipline Lab Natl Def Biotechnol Uranium Mi, Hengyang 421001, Peoples R China.;[Li, Le] Univ South China, Sch Publ Hlth, Hengyang 421001, Peoples R China.
通讯机构：
[Ding, DX] Univ South China, Key Discipline Lab Natl Def Biotechnol Uranium Mi, Hengyang 421001, Peoples R China.
关键词：
Sodium feldspar;U(VI) ion adsorption;Low concentration aqueous solution;Kinetic;Water treatment
摘要：
The raw sodium feldspar (RSF) is activated with the concentrated sulfuric acid solution and the acid activated sodium feldspar (AASF) is obtained. The results obtained from the mercury intrusion method show that the acidification can increase the porosity and the specific surface area. The effects of the initial pH, contact time and ambient temperature on the adsorption of U(VI) ions are investigated in a batch process. The adsorption efficiency amounts to the highest at pH 6 and the adsorption equilibrium is reached in 600 min. The pseudo-second-order model is found to be more suitable for the adsorption process than the pseudo-first-order model and intra-particle model, indicating that the chemical adsorption is the predominant step for the adsorption process. Langmuir model is found to describe the adsorption process better than Freundlich model. This proves that the main form of U(VI) ions attached to RSF and AASF is the monolayer coverage. The thermodynamic parameters prove that the adsorption process is a spontaneous endothermic one. It was also found that acid activated treatment can help increase the adsorption rate and capacity. The results show that RSF and AASF can be used as a novel low cost adsorbent for removal of U(VI) ions from the low concentration aqueous solution.
摘要：
The anaerobic microcosms amended with 30 mM bicarbonate and without bicarbonate were established, respectively, and the reduction of U(VI) in the microcosms by functionalized indigenous microbial communities was investigated. Results of the chemical extraction and XANES analysis showed that the proportions of U(IV) in the microcosms amended with bicarbonate were 10 % lower than without bicarbonate at day 46. The amount of Cellulomonadaceae, Desulfovibrionaceae, Peptococcaceae and Veillonellaceae amended with bicarbonate was lower than without bicarbonate, so the reduction of U(VI) was less. The experimental results show that the high concentration bicarbonate has a significantly inhibitory effect on the reduction of U(VI).
作者机构：
[Tan, Yan; Hu, Nan; Xue, Jinhua; Wang, Yongdong; Xin, Xin; Zhang, Hui; Ding, Dexin; Li, Le] Key Discipline Laboratory for National Defense for Biotechnology in Uranium Mining and Hydrometallurgy, University of South China, Hengyang, China;[Tan, Yan; Xue, Jinhua; Li, Le] School of Public Health, University of South China, Hengyang, China
通讯机构：
[Ding, DX] Univ South China, Key Discipline Lab Natl Def Biotechnol Uranium Mi, Hengyang 421001, Peoples R China.
关键词：
Adsorption and desorptions - Adsorption and recoveries - Adsorption conditions - Gibbs free energy changes - Intraparticle diffusion equation - Langmuir isotherm models - Pseudo-second order model - Radioactive wastewater
摘要：
The thermally activated sodium feldspar (TASF), a novel material, was prepared by calcinating the micron sodium feldspar (SF) at 450 A degrees C for 45 min. The TASF and the SF were characterized using X-ray diffraction and mercury injection porosimetry, and the TASF was found to have larger specific surface area and larger porosity than SF. The effects of the initial pH, temperature, contact time and initial U(VI) ions concentration on the adsorption of U(VI) ions from the low concentration uranium solution by TASF were investigated. The maximum adsorption efficiency of TASF for 0.5 mg/L uranium solution amounted to 95.49 % when the initial pH was 5.0, the temperature, 318 K, and and the contact time, 600 min. The relationship between the adsorption capacity q (e) and equilibrium concentration C (e) can well be described by Freundlich equation. Adsorption isotherm and the analysis by FT-IR coupled with SEM revealed that U(VI) ions were adsorbed onto the surface of TASF in multimolecular or cluster states, and that the intraparticle diffusion occurred in spontaneous process. The basic thermodynamic parameters including free energy change, entropy change and enthalpy change were calculated to comprehend the intrinsic features and spontaneous nature of the adsorption process. The FT-IR spectroscopic characterization for the TASF indicated that many groups were involved in the adsorption process of U(VI) ions, and the -OH group played a more important role. The experimental results suggested that TASF had great adsorption efficiency and strong potentiality of enrichment and recovery for the low concentration U(VI).
摘要：
The adsorption of U(VI) from low concentration solution by HKUST-1@H3PW12O40 was studied as a function of various experimental parameters including pH, interfering ions, contact time, initial uranium concentration and temperature by batch experiments. Equilibrium data were found to fit with Langmuir isotherm model better than Freundlich isotherm model. The kinetic adsorption was fitted by the pseudo-second-order model well. Thermodynamic data from the adsorption experiments indicate that adsorption process is spontaneous and endothermic. HKUST-1@H3PW12O40 can selectively adsorb U(VI) from multi-metal ion solutions and the adsorption capacity of HKUST-1@H3PW12O40 don't decrease significantly after three cycles of desorption-reuse. The results show that HKUST-1@H3PW12O40 is suitable for removal of U(VI) from low concentration solutions.
摘要：
Experiments on the removal and recovery of U(VI) from aqueous solution by tea waste were conducted. The adsorbent was characterized by scanning electron microscope and energy dispersive spectrometer before and after the adsorption treatment. The removal of U(VI) amounts to 86.80 % at optimum pH 6. The adsorption process reaches its equilibrium in 12 h at 308 K, and the kinetic characteristic can be described by the pseudo-second-order kinetic equation. The amount of adsorption increases from 22.92 to 142.21 mg g(-1) with the decrease of tea waste dosage from 100 to 10 mg for solution with an initial uranium concentration of 50 mg L-1. Desorption for the four strippants is higher than 80 %. The equilibrium data are more agreeable with Freundlich isotherm than Langmuir isotherm.
期刊：
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals,2015年25(11):3237-3245 ISSN：1004-0609
通讯作者：
Peng, Guo-Wen(pgwnh@sohu.com)
作者机构：
[ Zhang, Zhi-Jun ; Ding, De-Xin ; Peng, Guo-Wen ; Xiao, Fang-Zhu ; Hu, Nan ] Key Discipline Laboratory for National Defence for Biotechnology in Uranium Mining and Hydrometallurgy, University of South China, Hengyang, China;[Peng, Guo-Wen ; Wang, Xiao-Liang ] School of Chemistry and Chemical Engineering, University of South China, Hengyang, China;[ Zhou, Gui ; Huang, Hong ; Yang, Jin-Ran ] Wang Chuanshan College, University of South China, Hengyang, China;[Peng, Guo-Wen ] School of Resources and Safety Engineering, Central South University, Changsha, China
关键词：
Adsorption isotherm model - Adsorption kinetics - Adsorption temperature - Correlation coefficient - Functional modification - Initial concentration - Mesoporous Silica - Pseudo-second order model
摘要：
Many kinetic models for heap leaching of low grade ores have been proposed and the model parameters have been treated as constants. However, some of these model parameters change with the depth of the heap. In the present work an apparatus consisted of six columns with different heights was designed and used to simulate the leaching behavior within a 3-m-high uranium ore heap at a uranium mine in South China. It was found that the model parameters alpha and omega for heap leaching of the uranium ore varied with the depth of the heap, and that the relationships between alpha and between omega and the depth of the heap were in the form of the logistic and the quadratic functions, respectively. Furthermore, a kinetic model for heap leaching of the uranium ore considering the variation of the model parameters with the depth of the ore was proposed. The kinetic model gave the fitting precision of more than 95 % and prediction precision of more than 93 %. The present work provided an approach for establishing the kinetic model for heap leaching of low grade uranium ores.
通讯机构：
[Ding, DX] Univ South China, Key Discipline Lab Natl Def Biotechnol Uranium Mi, Hengyang 421001, Peoples R China.
关键词：
Fractal kinetic model;Heap leaching;Fractal dimension;Uranium ore;Particle size distribution
摘要：
The varied particle size distribution of uranium ore for heap leaching, with its particle sizes ranging from 0 to 9 mm, is taken from a uranium mine in South China. Five uranium ore samples with the fractal dimensions (D) of particle size distribution of 1.6, 1.8, 2.0, 2.2 and 2.4, respectively, are further prepared by mixing different weights of the uranium ores for the size fractions of +8/-9, +7/-8, +6/-7, +5/-6, +4/-5, +3/-4, +2/-3, +1/-2, +0.5/-1 and -0.5 mm, respectively. The five samples are leached in columns to investigate the influences of the fractal dimensions of particle size distribution on their leaching performances. The leaching data are analyzed using the shrinking core model, and the whole process of the column leaching is divided into two phases based on the pH and the potential vs. saturated calomel electrode (SCE) of the pregnant leach solution (PLS) from the columns. When the value of pH is greater than 2.0 and the potential vs. SCE is less than 400 my, the leaching is in the first phase, the rate constant during the first phase k(1) is controlled by initial rate constant k(0) and the increase rate parameter lambda, and k(0), lambda and the length of the period for the first phase T-1 all have linear relationships with D. When the value of pH is less than or equal to 2.0 and the potential vs. SCE is greater than or equal to 400 mV, the leaching is in the second phase, and the rate constant during the second phase k(2) has non-linear relationship with D. From these analytical results, a fractal kinetic model for heap leaching of the uranium ore with fractal dimension of varied particle size distribution is established. And the experimental results show that the model is capable of predicting the recovery of uranium for heap leaching of uranium ore with fractal dimension of varied particle size distribution. (C) 2013 Elsevier B.V. All rights reserved.
作者：
Ding, De Xin;Xin, Xin;Li, Le;Hu, Nan;Li, Guang Yue;Wang, Yong Dong;Fu, Ping Kun
期刊：
Water, Air, and Soil Pollution,2014年225(12) ISSN：0049-6979
通讯作者：
Ding, DX
作者机构：
[Hu, Nan; Wang, Yong Dong; Fu, Ping Kun; Li, Guang Yue; Xin, Xin; Ding, De Xin] Key Discipline Laboratory for National, Defense for Biotechnology in Uranium Mining and Hydrometallurgy, University of South China, Hengyang, China;[Li, Le] School of Public Health, University of South China, Hengyang, China
通讯机构：
[Ding, DX] Univ South China, Key Discipline Lab Natl Def Biotechnol Uranium Mi, Hengyang 421001, Peoples R China.
摘要：
In order to develop an effective and economical method for removing U(VI) from the low concentration radioactive wastewater with the U(VI) concentration of less than 1 mg L<sup>-1</sup>, the biomass of Aspergillus niger was prepared and modified with ethylenediamine, and the biosorption of uranium from the low concentration radioactive wastewater by the unmodified and the modified biomasses was investigated in a batch system. The modified biomass exhibited the adsorption efficiency of 99.25 % for uranium under the optimum conditions that pH was 5.0, the contact time was 150 min, and the biosorbent dose was 0.2 g L<sup>-1</sup>. The adsorption fitted well to Langmuir isotherm, and the maximum sorption capacity of the modified biomass for U(VI) was determined to be 6.789 mg g<sup>-1</sup> which increased by 36.45 % compared with the unmodified biomass. The adsorption kinetics was better depicted by pseudo-second-order kinetic model. The Gibbs free energy change (ΔG <sup>0</sup>), enthalpy change (ΔH <sup>0</sup>), and entropy change (ΔS <sup>0</sup>) showed that the process of U(VI) adsorption was spontaneous, endothermic, and feasible. The changes in the groups, morphology, and the presence of U(VI) on the surface of the adsorbents which were characterized by FT-IR, SEM, and EDS, demonstrated that the U(VI) was successfully adsorbed onto the modified biomass. Moreover, the UO<inf>2</inf> <sup>2+</sup> absorbed on the modified biomass can be released by 0.1 mol L<sup>-1</sup> HNO<inf>3</inf> with high desorption efficiency of 99.21 %. The results show that the modified biomass can remove U(VI) from low concentration radioactive wastewater more effectively than the unmodified biomass.