It is quite important to ensure the safety and sustainable development of nuclear energy for the treatment of radioactive wastewater. To treat radioactive wastewater efficiently and rapidly, two multi-amine β-cyclode...It is quite important to ensure the safety and sustainable development of nuclear energy for the treatment of radioactive wastewater. To treat radioactive wastewater efficiently and rapidly, two multi-amine β-cyclodextrin polymers(diethylenetriamine β-cyclodextrin polymer(DETA-TFCDP) and triethylenetetramine β-cyclodextrin polymer(TETA-TFCDP)) were prepared and applied to capture uranium. Results exhibited that DETA-TFCDP and TETA-TFCDP displayed the advantages of high adsorption amounts(612.2and 628.2 mg·g-1, respectively) and rapid adsorption rates, which can reach(88 ± 1)% of their equilibrium adsorption amounts in 10 min. Moreover, the adsorbent processes of DETA-TFCDP and TETATFCDP on uranium(Ⅵ) followed the Langmuir model and pseudo-second-order model, stating they were mainly chemisorption and self-endothermic. Besides, TETA-TFCDP also showed excellent selectivity in the presence of seven competing cations and could be effectively reused five times via Na2CO3as the desorption reagent. Meanwhile, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy illustrated that the enriched multi-amine groups and oxygen-containing functional groups on the surface of TETA-TFCDP were the main active sites for capturing uranium(Ⅵ). Hence, multi-amine β-cyclodextrin polymers are a highly efficient, rapid, and promising adsorbent for capturing uranium(Ⅵ)from radioactive wastewater.展开更多
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
Amidoxime-functionalized ultra-high molecular weight polyethylene fibers(UHMWPEF-AO) were used to absorb uranium U(VI) from aqueous solutions.In this paper,we study effects of pH,initial U(VI) concentration,contact ti...Amidoxime-functionalized ultra-high molecular weight polyethylene fibers(UHMWPEF-AO) were used to absorb uranium U(VI) from aqueous solutions.In this paper,we study effects of pH,initial U(VI) concentration,contact time,and temperature on U(VI) adsorption by UHMWPEF-AO.The adsorption process agrees well with pseudo-second-order and Langmuir model.UHMWPEFAO exhibits excellent adsorptive performance for U(VI)with a maximum adsorption capacity of 176.12 mg/g at pH4 and 298 K.The structures of UHMWPEF-AO and U(VI)-loaded UHMWPEF-AO are characterized by FT-IR and nano-CT.U(VI)-loaded UHMWPEF-AO is sintered after adsorption process to recycle absorbed U(VI).Powders collected after sintering process are examined by scanning electron microscopy and X-ray diffraction.These results indicate that UHMWPEF-AO is a promising candidate to remove U(VI) from uranium aqueous solutions.展开更多
The sorption of the uranium(VI) ions from aqueous solutions by diethylethanolammonium organovolcanics(Kula-TURKEY) was investigated under different experimental conditions. DEEA was used to modify the surface of basal...The sorption of the uranium(VI) ions from aqueous solutions by diethylethanolammonium organovolcanics(Kula-TURKEY) was investigated under different experimental conditions. DEEA was used to modify the surface of basaltic volcanics. The characteristic of basaltic volcanic was analyzed by XRF, SEM–EDS, FTIR, and XRD. The BET surface areas of unmodified volcanics and DEEA-modified volcanics were found as 2.265 and3.689 m^2/g, respectively. The volcanic samples were treated by using different concentrations of DEEA. The adsorption of U(VI) on natural and modified volcanics was examined as a function of the contact time, initial p H of the solution, initial U(VI) concentration, and temperature.Langmuir, Freundlich, and D–R adsorption isotherms were used to describe the adsorption. While examining the adsorption percentage and distribution coefficient, these values for unmodified volcanics were found to be25% ± 0.76 and 10.08 m L/g, while the values for the DEEA-modified volcanics were 88% ± 1.04 and 220 m L/g, respectively. The pseudo-first-order and pseudo-secondorder kinetic models were used to describe the kinetic data.In this study, it can be seen that the adsorption process is suitable for the pseudo-second-order kinetic model. Various thermodynamic parameters(ΔG°, ΔH°, and ΔS°) were calculated with the thermodynamic distribution coefficients obtained at different temperatures. The sorption process was a chemical adsorption process. The results indicated that the processes are spontaneous and endothermic.展开更多
基金National Natural Science Foundation of China(21603064,52102214)Natural Science Foundation of Jiangxi Province(20202BABL203026,20212BAB203001,20202BABL214016)College Student Innovation and Enterprise Programme of Jiangxi Province(S202310405010)provided funding for this study.
文摘It is quite important to ensure the safety and sustainable development of nuclear energy for the treatment of radioactive wastewater. To treat radioactive wastewater efficiently and rapidly, two multi-amine β-cyclodextrin polymers(diethylenetriamine β-cyclodextrin polymer(DETA-TFCDP) and triethylenetetramine β-cyclodextrin polymer(TETA-TFCDP)) were prepared and applied to capture uranium. Results exhibited that DETA-TFCDP and TETA-TFCDP displayed the advantages of high adsorption amounts(612.2and 628.2 mg·g-1, respectively) and rapid adsorption rates, which can reach(88 ± 1)% of their equilibrium adsorption amounts in 10 min. Moreover, the adsorbent processes of DETA-TFCDP and TETATFCDP on uranium(Ⅵ) followed the Langmuir model and pseudo-second-order model, stating they were mainly chemisorption and self-endothermic. Besides, TETA-TFCDP also showed excellent selectivity in the presence of seven competing cations and could be effectively reused five times via Na2CO3as the desorption reagent. Meanwhile, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy illustrated that the enriched multi-amine groups and oxygen-containing functional groups on the surface of TETA-TFCDP were the main active sites for capturing uranium(Ⅵ). Hence, multi-amine β-cyclodextrin polymers are a highly efficient, rapid, and promising adsorbent for capturing uranium(Ⅵ)from radioactive wastewater.
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.
基金supported by the National Natural Science Foundation of China(Grants No.U1532259)
文摘Amidoxime-functionalized ultra-high molecular weight polyethylene fibers(UHMWPEF-AO) were used to absorb uranium U(VI) from aqueous solutions.In this paper,we study effects of pH,initial U(VI) concentration,contact time,and temperature on U(VI) adsorption by UHMWPEF-AO.The adsorption process agrees well with pseudo-second-order and Langmuir model.UHMWPEFAO exhibits excellent adsorptive performance for U(VI)with a maximum adsorption capacity of 176.12 mg/g at pH4 and 298 K.The structures of UHMWPEF-AO and U(VI)-loaded UHMWPEF-AO are characterized by FT-IR and nano-CT.U(VI)-loaded UHMWPEF-AO is sintered after adsorption process to recycle absorbed U(VI).Powders collected after sintering process are examined by scanning electron microscopy and X-ray diffraction.These results indicate that UHMWPEF-AO is a promising candidate to remove U(VI) from uranium aqueous solutions.
基金supported by the Manisa Celal Bayar University(No.BAP 2012-005)
文摘The sorption of the uranium(VI) ions from aqueous solutions by diethylethanolammonium organovolcanics(Kula-TURKEY) was investigated under different experimental conditions. DEEA was used to modify the surface of basaltic volcanics. The characteristic of basaltic volcanic was analyzed by XRF, SEM–EDS, FTIR, and XRD. The BET surface areas of unmodified volcanics and DEEA-modified volcanics were found as 2.265 and3.689 m^2/g, respectively. The volcanic samples were treated by using different concentrations of DEEA. The adsorption of U(VI) on natural and modified volcanics was examined as a function of the contact time, initial p H of the solution, initial U(VI) concentration, and temperature.Langmuir, Freundlich, and D–R adsorption isotherms were used to describe the adsorption. While examining the adsorption percentage and distribution coefficient, these values for unmodified volcanics were found to be25% ± 0.76 and 10.08 m L/g, while the values for the DEEA-modified volcanics were 88% ± 1.04 and 220 m L/g, respectively. The pseudo-first-order and pseudo-secondorder kinetic models were used to describe the kinetic data.In this study, it can be seen that the adsorption process is suitable for the pseudo-second-order kinetic model. Various thermodynamic parameters(ΔG°, ΔH°, and ΔS°) were calculated with the thermodynamic distribution coefficients obtained at different temperatures. The sorption process was a chemical adsorption process. The results indicated that the processes are spontaneous and endothermic.
