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Xuemei Ren Suowei Wang Shitong Yang Jiaxing Li 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(1):253-259
The sorption of U(VI) from aqueous solution on MX-80 bentonite was studied as a function of contact time, pH, ionic strength,
solid contents, humic acid (HA), fulvic acid (FA) and temperature under ambient conditions using batch technique. The results
indicate that sorption of U(VI) on MX-80 bentonite is strongly dependent on pH and ionic strength. The removal of U(VI) to
MX-80 bentonite is rather quick and the kinetic sorption data is simulated well by a pseudo-second-order rate equation. The
presence of HA enhances the sorption of U(VI) on MX-80 bentonite obviously, but the influence of FA on U(VI) sorption is not
obvious. The thermodynamic parameters (ΔH
0, ΔS
0, and ΔG
0) for the sorption of U(VI) calculated from temperature dependent sorption suggest that the sorption reaction is endothermic
and spontaneous. 相似文献
3.
Ping Li Qiao-hui Fan Duo-qiang Pan Sheng-ping Liu Wang-suo Wu 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(3):757-764
Effects of pH, Eu(III) concentration, ionic strength, temperature and humic acid (HA) on Eu(III) sorption to iron oxides were
investigated in detail. The sorption of Eu(III) to iron oxides was significantly dependent on pH and weakly dependent on ionic
strength, and higher temperature was gainful to Eu(III) sorption. In the presence of HA, Eu(III) sorption was enhanced significantly
at low pH; whilst obvious negative effect was observed in higher pH range. Below 12 mg/L HA, HA could obviously enhanced Eu(III)
sorption to iron oxides, nevertheless Eu(III) sorption decreased steeply with increasing HA while HA exceeded 12 mg/L. The
results were helpful for understanding radionuclides behaviors in natural environment. 相似文献
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Weigang Du Xuemei Liu Liqiang Tan 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(3):1173-1179
Attapulgite has been applied in the sorption of metal and radionuclide ions since its discovery. Herein, radionuclide Am(III)
sorption onto attapulgite was carried out at 25 °C in 0.01 mol/L NaNO3 solutions. Effects of contact time, Am(III) initial concentration, pH, humic acid and temperature on Am(III) sorption onto
attapulgite were investigated. The sorption of Am(III) increases with increasing contact time and reaches a maximum value
within 24 h at different Am(III) initial concentration. The fast sorption velocity indicates that strong chemical sorption
or strong surface complexation contributes to the sorption of Am(III) onto attapulgite under the experimental conditions.
The experimental data can be described well by the pseudo-second-order rate model. The sorption of Am(III) onto attapulgite
is strongly dependent on pH values and surface complexation is the main sorption mechanism. The presence of HA enhances the
sorption of Am(III) onto attapulgite at pH < 8.5, whereas, at pH > 8.5, little effect of HA on Am(III) sorption is observed.
The Langmuir, Freundlich and D-R models were used to simulate the sorption data at different pH values and the results indicated
that Langmuir model simulates the experimental data better than Freundlich and D-R models. The thermodynamic parameters indicates
that the sorption of Am(III) onto attapulgite is an endothermic and spontaneous process. The results suggest that the attapulgite
is a suitable material as an adsorbent for preconcentration and immobilization of Am(III) from aqueous solutions. 相似文献
6.
Y. Q. Wang Q. H. Fan P. Li X. B. Zheng J. Z. Xu Y. R. Jin W. S. Wu 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(1):231-237
The sorption of Eu(III) on calcareous soil as a function of pH, humic acid (HA), temperature and foreign ions was investigated
under ambient conditions. Eu(III) sorption on soil was strongly pH dependent in the observed pH range. The effect of ionic
strength was significant at pH < 7, and not obvious at pH > 8. The type of salt cation used had no visible influence on Eu(III)
uptake on soil, however at low pH values, the influence of anions was following the order: Cl− ≈ NO3
− > ClO4
−. In the presence of HA, the sorption edge obviously shifted about two pH units to the lower pH, whilst in range of pH 6–7,
the sorption of Eu(III) decreased with increasing pH because a considerable amount of Eu(III) was present as humate complexes
in aqueous phase, then increased again at pH > 11. The results indicated that the sorption of Eu(III) on soil mainly formed
outer-sphere complexes and/or ion exchange below pH ~7; whereas inner-sphere complexes and precipitation of Eu(OH)3(s) may play main role above pH ~8. 相似文献
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Effect of pH,ionic strength and humic substances on the adsorption of Uranium (VI) onto Na-rectorite
Donglin Zhao Shubin Yang Shaohua Chen Zhiqiang Guo Xin Yang 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(2):557-565
In this study, the adsorption of U(VI) from aqueous solution on Na-rectorite was studied as a function of various environmental
conditions such as contact time, pH, ionic strength, soil humic acid (HA)/fulvic acid (FA), solid contents, and temperature
under ambient conditions by using batch technique. The kinetic adsorption is fitted by the pseudo-second-order model very
well. The adsorption of U(VI) on Na-rectorite was strongly dependent on pH and ionic strength. A positive effect of HA/FA
on U(VI) adsorption was found at low pH, whereas a negative effect was observed at high pH. The presence of HA/FA enhanced
the U(VI) adsorption at low pH values, but reduced U(VI) adsorption at high pH. The thermodynamic parameters (ΔH
0, ΔS
0, and ΔG
0) were also calculated from the temperature dependent adsorption isotherms, and the results suggested that the adsorption
of U(VI) on Na-rectorite was a spontaneous and endothermic process. 相似文献
9.
P. Chang S. Yu T. Chen A. Ren C. Chen X. Wang 《Journal of Radioanalytical and Nuclear Chemistry》2007,274(1):153-160
Sorption of Th(IV) on Na-rectorite as a function of pH, ionic strength, soil humic acid (HA) and fulvic acid (FA) are studied
under ambient conditions by using a batch technique. The results indicate that the sorption of Th(IV) on Na-rectorite is not
only dependent on medium pH values, but also dependent on medium ionic strength and humic substances. Surface complexation
and cation competition exchange account for Th(IV) sorption on Na-rectorite. The sorption of Th(IV) on Na-rectorite decreases
with the increase on the concentration of NaNO3, Mg(NO3)2 and Ca(NO3)2, and increases with the increasing amount of HA/FA in the suspension/adsorbed on rectorite. Soil HA/FA enhances the sorption
of Th(IV) on rectorite at medium pH<4 drastically, but the presence of FA reduces the sorption of Th(IV) at medium pH>6, and
HA has no effect on Th(IV) sorption at medium pH>6. An interpretation for the results is attempted, considering the occurrence
of different sorption mechanisms. 相似文献
10.
Xiaoping Song Yajie Wang Jingjing Cai Songsheng Lu Yunfei Chen 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):685-695
The interaction of U(VI) with Na-attapulgite was studied by using batch technique at different experimental conditions. The effect of contact time, solid content, pH, ionic strength and temperature on the sorption of U(VI) onto Na-attapulgite in the presence and absence of humic acid was also investigated. The results showed that the sorption of U(VI) on Na-attapulgite achieved sorption equilibrium quickly. Sorption of U(VI) on Na-attapulgite increased quickly with increasing pH at pH < 6.5, and then decreased with pH increasing at pH > 6.5. The sorption curves were shifted to left in low NaClO4 solutions as compared those in high NaClO4 solutions. The sorption was strongly dependent on pH and ionic strength. The sorption was dominated by ion exchange or outer-sphere surface complexation at low pH values, and by inner-sphere surface complexation or surface precipitation at high pH values. The thermodynamic parameters (i.e., ΔH 0, ΔS 0, and ΔG 0) for the sorption of U(VI) were calculated from the temperature dependent sorption isotherms, and the results suggested that the sorption reaction was an endothermic and spontaneous process. The Na-attapulgite is a suitable material in the removal and preconcentration of U(VI) from large volumes of aqueous solutions in nuclear waste management. 相似文献
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Wubiao Zhu Zhengjie Liu Lei Chen Yunhui Dong 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(3):781-788
Sorption of U(VI) from aqueous solution to Na-attapulgite was investigated at different experimental chemistry conditions
by using batch technique. The attapulgite sample was characterized by FTIR and XRD. Sorption of U(VI) on attapulgite was strongly
dependent on pH and ionic strength. The sorption of U(VI) on attapulgite increased quickly with rising pH at pH < 6, and decreased
with increasing pH at pH > 7. The presence of humic acid (HA) enhanced the sorption of U(VI) on attapulgite obviously at low
pH because of the strong complexation of surface adsorbed HA with U(VI) on attapulgite surface. Sorption of U(VI) on attapulgite
was mainly dominated by ion exchange and/or outer-sphere surface complexation at low pH values, whereas the sorption was attributed
to the inner-sphere surface complexation or precipitation at high pH values. The sorption increased with increasing temperature
and the thermodynamic parameters calculated from the temperature dependent sorption isotherms suggested that the sorption
of U(VI) on attapulgite was a spontaneous and endothermic process. The results indicate that attapulgite is a very suitable
material for the preconcentration of U(VI) ions from large volumes of aqueous solutions. 相似文献
14.
Kan Li Jun Hu Zhengjie Liu Lei Chen Yunhui Dong 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(3):2125-2133
Multiwalled carbon nanotubes (MWCNTs) have attracted intense multidisciplinary study because of their special physicochemical properties. In this paper, the effect of solid content, contact time, pH, temperature and humic acid on radionuclide (60Co(II)) on MWCNTs was studied by using batch technique. The results indicate that the sorption of Co(II) on MWCNTs can achieve sorption equilibration in short time and the kinetic sorption can be described by pseudo-second-order model well. The sorption of Co(II) on MWCNTs is strongly dependent on pH and independent of ionic strength, suggesting that the sorption of Co(II) on MWCNTs is mainly dominated by inner-sphere surface complexation rather than by outer-sphere surface complexation or ion exchange. The thermodynamic parameters calculated from the temperature-dependent sorption isotherms indicate that the sorption of Co(II) on MWCNTs was an endothermic and spontaneous process. The results of high sorption capacity of Co(II) suggest that MWCNTs can be used as efficient materials for the preconcentration of radiocobalt from large volumes of aqueous solutions in radionuclide polluted water. 相似文献
15.
Liang Gao Ziqian Yang Keliang Shi Xuefeng Wang Zhijun Guo Wangsuo Wu 《Journal of Radioanalytical and Nuclear Chemistry》2010,284(3):519-526
U(VI) sorption on kaolinite was studied as functions of contact time, pH, U(VI) concentration, solid-to-liquid ratio (m/V) by using a batch experimental method. The effects of sulfate and phosphate on U(VI) sorption were also investigated. It
was found that the sorption kinetics of U(VI) can be described by a pseudo-second-order model. Potentiometric titrations at
variable ionic strengths indicated that the titration curves of kaolinite were not sensitive to ionic strength, and that the
pH of the zero net proton charge (pHPZNPC) was at 6.9. The sorption of U(VI) on kaolinite increased with pH up to 6.5 and reached a plateau at pH >6.5. The presence
of phosphate strongly increased U(VI) sorption especially at pH <5.5, which may be due to formation of ternary surface complexes
involving phosphate. In contrast, the presence of sulfate did not cause any apparent effect on U(VI) sorption. A double layer
model was used to interpret both results of potentiometric titrations and U(VI) sorption on kaolinite. 相似文献
16.
Sorption and desorption of radioeuropium on red earth and its solid components to remove organic matter was studied at pH
5.3±0.1 and 4.5±0.1, and in 0.01M and 0.001M NaClO4 solutions, respectively. Eu(III) sorption showed strong pH and humic acid concentration dependency, and NaClO4 concentration independency. The sorption increased with increasing pH and amount of HA adsorbed on red earth. The sorption
of Eu(III) on red earth was mainly dominated by surface complexation. Humic acid and high pH had a great tendency to immobilize
the movement of Eu(III) in red earth. Sorption-desorption hysteresis of Eu(III) on red earth indicated that the sorption was
irreversible. 相似文献
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Lei Chen Xianjin Yu Zengdian Zhao 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(1):187-193
A highly sensitive separation procedure has been developed to investigate uranium and thorium activities and their isotopic
ratios in environmental water samples in Tokushima, Japan. Uranium and thorium isotopes in environmental water samples were
simultaneously isolated from interfering elements with extraction chromatography using an Eichrom UTEVA™ resin column. After
the chemical separation, activities of U and Th isotopes coprecipitated with samarium fluoride (SmF3) were measured by α-spectrometry. It has been confirmed that uranium isotopes are isolated successfully from thorium decay
chains by analyzing a test aqueous solution as a simulation of an environmental water sample. The separation procedure has
been first applicable to the determination of U and Th activities and their isotopic ratios in a drinking well water named
“Kurashimizu” in Tokushima City, Japan. The specific activities of 238U and 232Th in “Kurashimizu” were deduced to be within the upper limits of <0.31 and <0.19 mBq/l, respectively. 相似文献
18.
Su-Wen Chen Bo-Long Guo Yu-Long Wang Yuan Li Li-Juan Song 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(2):1435-1442
The mesoporous silicas (MCM-41 and MCM-48) are synthesized by hydrothermal method, which are characterized by XRD and BET techniques. The application of mesoporous silicas for the sorption of U(VI) from aqueous solution are studied by using batch technique under ambient condition. The effects of contact time, solid-to-liquid ratio (m/V), solution pH, ionic strength and temperature are determined, and the results indicate that the sorption of U(VI) to MCM-41 or MCM-48 are strongly dependent on pH values but independent of ionic strength. Compared with Langmuir model, the sorption isotherms can be simulated by Freundlich model well according to the high relative coefficients. The parameters for Langmuir and Freundlich sorption isotherms are calculated from the temperature at 298, 318 and 338 K, respectively, and the results suggest that the sorption of U(VI) on MCM-41 or MCM-48 is a spontaneous and exothermic process. In contrast to its sorption capacity for U(VI), MCM-48 is a suitable material for the preconcentration of U(VI) from large volumes of aqueous solutions. 相似文献
19.
Lu Songsheng Xu Hua Wang Mingming Song Xiaoping Liu Qiong 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(2):889-895
The bentonite from Gaomiaozi county (Inner Mongolia, China) (denoted as GMZ bentonite) was characterized by X-ray powder diffraction
and Fourier transform infrared spectroscopy. The effect of pH, contact time, ionic strength, humic acid (HA) and Eu(III) concentrations
on Eu(III) sorption to the GMZ bentonite was studied by batch technique under ambient conditions. The sorption of Eu(III)
on GMZ bentonite was strongly dependent on pH and independent of ionic strength. The sorption of Eu(III) on GMZ bentonite
was mainly dominated by surface complexation rather than by ion exchange. The presence of HA enhanced Eu(III) sorption at
low pH values, but decreased Eu(III) sorption at high pH values. The enhanced sorption of Eu(III) on GMZ bentonite at low
pH was attributed to the strong complexation of Eu(III) with surface adsorbed HA on GMZ bentonite and the reduced sorption
of Eu(III) at high pH was attributed to the formation of soluble HA–Eu complexes in aqueous solution. The strong sorption
of Eu(III) on GMZ bentonite suggested that the GMZ bentonite could be used as the backfill material in nuclear waste disposal. 相似文献
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Mingming Wang Jun Qiu Xinquan Tao Cuiping Wu Weibing Cui Qiong Liu Songsheng Lu 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(3):895-901
Multiwalled carbon nanotubes (MWCNTs) have attracted multidisciplinary study because of their unique physicochemical properties. Herein, the sorption of U(VI) from aqueous solution to oxidized MWCNTs was investigated as a function of contact time, pH and ionic strength. The results indicate that U(VI) sorption on oxidized MWCNTs is strongly dependent on pH and ionic strength. The sorption of U(VI) is mainly dominated by surface complexation and cation exchange. The sorption of U(VI) on oxidized MWCNTs is quickly to achieve the sorption equilibrium. The sorption capacity calculated from sorption isotherms suggests that oxidized MWCNTs are suitable material in the preconcentration and solidification of U(VI) from large volumes of aqueous solutions. 相似文献