The adsorption of uranium(Ⅵ)on the manganese oxide coated zeolite(MOCZ)from aqueous solution was investigated in a fixed-bed column.The experiments were conducted to investigate the effects of bed height,flow rate,pa...The adsorption of uranium(Ⅵ)on the manganese oxide coated zeolite(MOCZ)from aqueous solution was investigated in a fixed-bed column.The experiments were conducted to investigate the effects of bed height,flow rate,particle size,initial concentration of uranium(Ⅵ),initial pH,presence of salt and competitive ions.The U-uptake by MOCZ increased with initial uranium(Ⅵ)concentration and bed height,but decreased as the flow rate and particle size increased.In the presence of salt and competitive ions,the breakthrough time was shorter.The adsorption capacity reached a maximum at pH of 6.3.The Thomas model was applied to the experimental data to determine the characteristic parameters of the column for process design using linear regression.The breakthrough curves calculated from the model were in good agreement with the experimental data.The BDST model was used to study the influence of bed height on the adsorption of uranium(Ⅵ).Desorption of uranium(Ⅵ)in the MOCZ column was investigated.The column could be used for at least four adsorption-desorption cycles using 0.1mol.L-1 NaHCO3 solution as the elution.After desorption and regeneration with deionized water,MOCZ could be reused to adsorb uranium(Ⅵ)at a comparable capacity.Compared to raw zeolite,MOCZ showed better capacity for uranium(Ⅵ)removal.展开更多
This work was conducted to determine the practicability of using a new adsorbent 4-ethyl thiosemicarbazide intercalated, organophilic calcined hydrotalcite （ETSC-OHTC） for the removal of uranium （U（Ⅵ））, and tho...This work was conducted to determine the practicability of using a new adsorbent 4-ethyl thiosemicarbazide intercalated, organophilic calcined hydrotalcite （ETSC-OHTC） for the removal of uranium （U（Ⅵ））, and thorium （Th（Ⅳ）） from water and wastewater. The FTIR analysis helped in realizing the involvement of nitrogen and sulphur atoms of ETSC in binding the metal ions through complex formation. Parameters like adsorbent dosage, solution pH, initial metal ions concentration, contact time and ionic strength, that influence adsorption phenomenon, were studied. The optimum pH for maximum adsorption of U（VI） and Th（IV） was found to be in the range 4.0-6.0. The contact time required for reaching equilibrium was 4 hr. The pseudo second-order kinetic model was the best fit to represent the kinetic data. Analysis of the equilibrium adsorption data using Langmuir, Freundlich and Sips models showed that the Freundlich model was well suited to describe the metal ions adsorption. The KF values were 25.43 and 29.11 mg/g for U（Ⅵ） and Th（Ⅳ）, respectively, at 30℃. The adsorbent can be regenerated effectively from U（Ⅵ） and Th（Ⅳ） loaded ones using 0.01 mol/L HC1. The new adsorbent was quite stable for many cycles, without much reduction in its adsorption capacity towards the metals.展开更多
Amidoxime-based adsorbents are widely studied as the main adsorbent in the recovery of uranium from seawater. However, the adsorption rate and loading capacity of such adsorbents should be further improved due to the ...Amidoxime-based adsorbents are widely studied as the main adsorbent in the recovery of uranium from seawater. However, the adsorption rate and loading capacity of such adsorbents should be further improved due to the economic viability consider- ation. In this paper, polyvinyl alcohol functionalized with amidoxime （PVA-g-AO） has been prepared as a new adsorbent for uranium （VI） adsorption from aqueous solution. The physicochemical properties of PVA-g-AO were investigated using infra- red spectroscopy （IR）, scanning electron microscope （SEM）, X-ray diffraction （XRD）, and X-ray photoelectron spectroscopy （XPS）. Results showed that the ligand monomers were successfully grafted onto the matrixes. The XRD and XPS analysis showed that uranium was adsorbed in metal ionic form rather than in crystal form. Uranyl （U （VI）） adsorption properties onto PVA-g-AO were evaluated. The adsorption of U （VI） by PVA-g-AO was fast, with an equilibrium time of less than 50 rnin. Additionally the maximum adsorption capacity reached 42.84 mg/g at pH 4.0.展开更多
基金Supported by the National Science Foundation for Postdoctoral Sciemists of China （20070420811） and the Science and Technology Department of Henan Province in China （200510459016）.
文摘The adsorption of uranium(Ⅵ)on the manganese oxide coated zeolite(MOCZ)from aqueous solution was investigated in a fixed-bed column.The experiments were conducted to investigate the effects of bed height,flow rate,particle size,initial concentration of uranium(Ⅵ),initial pH,presence of salt and competitive ions.The U-uptake by MOCZ increased with initial uranium(Ⅵ)concentration and bed height,but decreased as the flow rate and particle size increased.In the presence of salt and competitive ions,the breakthrough time was shorter.The adsorption capacity reached a maximum at pH of 6.3.The Thomas model was applied to the experimental data to determine the characteristic parameters of the column for process design using linear regression.The breakthrough curves calculated from the model were in good agreement with the experimental data.The BDST model was used to study the influence of bed height on the adsorption of uranium(Ⅵ).Desorption of uranium(Ⅵ)in the MOCZ column was investigated.The column could be used for at least four adsorption-desorption cycles using 0.1mol.L-1 NaHCO3 solution as the elution.After desorption and regeneration with deionized water,MOCZ could be reused to adsorb uranium(Ⅵ)at a comparable capacity.Compared to raw zeolite,MOCZ showed better capacity for uranium(Ⅵ)removal.
文摘This work was conducted to determine the practicability of using a new adsorbent 4-ethyl thiosemicarbazide intercalated, organophilic calcined hydrotalcite （ETSC-OHTC） for the removal of uranium （U（Ⅵ））, and thorium （Th（Ⅳ）） from water and wastewater. The FTIR analysis helped in realizing the involvement of nitrogen and sulphur atoms of ETSC in binding the metal ions through complex formation. Parameters like adsorbent dosage, solution pH, initial metal ions concentration, contact time and ionic strength, that influence adsorption phenomenon, were studied. The optimum pH for maximum adsorption of U（VI） and Th（IV） was found to be in the range 4.0-6.0. The contact time required for reaching equilibrium was 4 hr. The pseudo second-order kinetic model was the best fit to represent the kinetic data. Analysis of the equilibrium adsorption data using Langmuir, Freundlich and Sips models showed that the Freundlich model was well suited to describe the metal ions adsorption. The KF values were 25.43 and 29.11 mg/g for U（Ⅵ） and Th（Ⅳ）, respectively, at 30℃. The adsorbent can be regenerated effectively from U（Ⅵ） and Th（Ⅳ） loaded ones using 0.01 mol/L HC1. The new adsorbent was quite stable for many cycles, without much reduction in its adsorption capacity towards the metals.
基金supported by the Science and Technology Development Foundation of China Academy of Engineering Physics(2011A0301003)
文摘Amidoxime-based adsorbents are widely studied as the main adsorbent in the recovery of uranium from seawater. However, the adsorption rate and loading capacity of such adsorbents should be further improved due to the economic viability consider- ation. In this paper, polyvinyl alcohol functionalized with amidoxime （PVA-g-AO） has been prepared as a new adsorbent for uranium （VI） adsorption from aqueous solution. The physicochemical properties of PVA-g-AO were investigated using infra- red spectroscopy （IR）, scanning electron microscope （SEM）, X-ray diffraction （XRD）, and X-ray photoelectron spectroscopy （XPS）. Results showed that the ligand monomers were successfully grafted onto the matrixes. The XRD and XPS analysis showed that uranium was adsorbed in metal ionic form rather than in crystal form. Uranyl （U （VI）） adsorption properties onto PVA-g-AO were evaluated. The adsorption of U （VI） by PVA-g-AO was fast, with an equilibrium time of less than 50 rnin. Additionally the maximum adsorption capacity reached 42.84 mg/g at pH 4.0.
