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1.
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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3.
Yong Qiu Shaoming Yu Leilei Cheng Feifei Lu 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(3):1673-1681
The acid-activated sepiolite (ASEP) was prepared by physical purification and acid activation of natural sepiolite, and was characterized by XRD, FT-IR, SEM and N2 adsorption–desorption. The prepared ASEP was applied for the sorption of 60Co(II) from aqueous solutions. The sorption of 60Co(II) from aqueous solutions by ASEP was investigated as a function of contact time, solid content, pH, ionic strength, foreign ions, humic acid (HA) and temperature. The results indicated that the sorption of 60Co(II) on ASEP was strongly dependent on pH values. At low pH, the sorption of 60Co(II) was dominated by outer-sphere surface complexation or ion exchange, whereas inner-sphere surface complexation or surface precipitation was the main sorption mechanism at high pH. The presence of HA increased the sorption of 60Co(II) on ASEP at low pH values, and reduced the sorption at high pH values. The Langmuir and Freundlich models were applied to simulate the sorption of 60Co(II) at three temperatures of 298, 318 and 338 K. The thermodynamic parameters ( $ \Updelta G^\circ ,\,\;\Updelta S^\circ $ and $ \Updelta H^\circ $ ) calculated from the temperature dependent sorption isotherms indicated that the sorption of 60Co(II) on ASEP was an endothermic and spontaneous process. ASEP has a great application potential for cost-effective disposal of 60Co(II) from large volumes of aqueous solutions. 相似文献
4.
Influence of pH,soil humic acid,ionic strength and temperature on sorption of U(VI) onto attapulgite
Liqiang Tan Xiaoli Tan Xuemei Ren Huiyang Mei Xiangke Wang 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(3):981-991
The surface property of attapulgite was investigated by N2-BET surface area and zeta potential analysis in this paper. Solution pH had a remarkable effect on the sorption process, indicated an inner-sphere complexation. Humic acid (HA) in the solution enhanced U(VI) sorption significantly at pH?<?5.0, while decreased U(VI) sorption obviously at pH?>?9.0. The characteristic fluorescence changes of HA indicated that a strong chemical reaction occurred between the functional groups in HA and UO22+. The sorption was a spontaneous and endothermic process with increased entropy, and the increase in temperature would benefit the sorption. 相似文献
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Chen Lei Xiangping Tian Baohua Ma 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(2):1127-1135
In this paper, the attapulgite-iron oxide magnetic composites were synthesized by coprecipitation method and were characterized by SEM, XRD and FTIR in detail. The characterization results indicated that the iron oxide was successfully formed on the surface of attapulgite. The prepared attapulgite-iron oxide magnetic composites were applied as adsorbents to remove Eu(III) from aqueous solutions by using batch sorption experiments under different experimental conditions. The sorption properties of Eu(III) on bare attapulgite were also performed as comparison. The results indicated that the sorption of Eu(III) on attapulgite-iron oxide magnetic composites was strongly dependent on pH and temperature. The attapulgite-iron oxide magnetic composites can be separated from aqueous solutions using magnetic separation method in large scale. At low pH values, the sorption of Eu(III) was influenced by ionic strength and pH obviously, while the sorption of Eu(III) was not affected by ionic strength at high pH values. The sorption of Eu(III) was dominated by ion exchange or outer-sphere surface complexation at low pH values, and mainly by inner-sphere surface complexation at high pH values. The thermodynamic parameters (i.e., ?G °, ?S °, ?H °) calculated from the temperature dependent sorption isotherms indicated that the sorption of Eu(III) on attapulgite-iron oxide magnetic composites was an endothermic and spontaneous process. Although the sorption capacities of Eu(III) on attapulgite-iron oxide magnetic composites were a little lower than those of Eu(III) on bare attapulgite, the magnetic separation in large scale is suitable for the application of the magnetic composites in the preconcentration of Eu(III) from large volumes of aqueous solutions in possible real applications. 相似文献
7.
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
8.
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
9.
Liu Xia Chen Yuantao Chi Yaling Guo Zhijun Cai Linsen 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(3):1357-1366
In this article, a series of batch experiments were carried out to investigate the effect of various environmental factors
such as contact time, solid content, pH, ionic strength, foreign ions, temperature and coexisting humic acid on the sorption
behavior radionuclide 60Co(II) on illite. The results indicated that the sorption of Co(II) was strongly dependent on pH, ionic strength and temperature.
At low pH, the sorption was dominated by outer-sphere surface complexation and ion exchange on illite surfaces, whereas inner-sphere
surface complexation was the main sorption mechanism at high pH. The Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models
were used to simulate the sorption isotherms at three different temperatures of 303.15, 323.15 and 343.15 K. The thermodynamic
data (∆G
0, ∆S
0, ∆H
0) were calculated from the temperature dependent sorption isotherms and the results suggested that the sorption process of
Co(II) on illite was an endothermic and spontaneous process. The sorption test revealed that the illite can be as a cost-effective
adsorbent suitable for pre-concentration of Co(II) from large volumes of aqueous solutions. 相似文献
10.
Yunhui Dong Zhengjie Liu Yueyun Li 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(1):257-265
Bentonite has been studied extensively because of its strong sorption and complexation ability. Herein, GMZ bentonite from
Gaomiaozi county (Inner Mongolia, China) was investigated as the candidate of backfill material for the removal of Th(IV)
ions from aqueous solutions. The results indicate that the sorption of Th(IV) is strongly dependent on pH and ionic strength
at pH < 5, and independent of ionic strength at pH > 5. Outer-sphere surface complexation or ion-exchange are the main mechanism
of Th(IV) sorption on GMZ bentonite at low pH values, whereas the sorption of Th(IV) at pH > 5 is mainly dominated by inner-sphere
surface complexation or surface precipitation. Soil fulvic acid (FA) and humic acid (HA) have a positive influence on the
sorption of Th(IV) on bentonite at pH < 5. The different addition sequences of HA and Th(IV) to GMZ bentonite suspensions
have no obvious effect on Th(IV) sorption to HA-bentonite hybrids. The high sorption capacity of Th(IV) on GMZ bentonite suggests
that the GMZ bentonite can remove Th(IV) ions from large volumes of aqueous solutions in real work. 相似文献
11.
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
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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
15.
Wang Mingming Xie Hongqin Tan Liqiang Qiu Jun Tao Xingquan Wu Cuiping 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(2):763-770
Herein, the sorption properties of Eu(III) on Na-attapulgite were performed by using batch sorption experiments under different
experimental conditions, such as contact time, pH, ionic strength, humic acid and temperatures. The results indicated that
the sorption of Eu(III) on Na-attapulgite was strongly dependent on pH and temperature. At low pH values, the sorption of
Eu(III) was influenced by ionic strength, whereas the sorption was not affected by ionic strength at high pH values. The sorption
of Eu(III) was mainly 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 sorption of Eu(III) onto Na-attapulgite increased with
increasing temperature. The Langmuir and Freundlich models were applied to simulate the sorption isotherms, and the results
indicated that the Langmuir model simulated the sorption isotherms better than the Freundlich model. The thermodynamic parameters
(∆G
o, ∆S
o, ∆H
o) were calculated from the temperature dependent sorption isotherms at 293, 313 and 333 K, respectively, and the results indicated
that the uptake of Eu(III) on Na-attapulgite was an endothermic and spontaneous process. The results of high Eu(III) sorption
capacity on Na-attapulgite suggest that the attapulgite is a suitable material for the preconcentration and immobilization
of Eu(III) ions from large volumes of aqueous solutions. 相似文献
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The adsorption of Am(III) (total concentration 10(-9) mol/l) on alumina, silica, and hematite was studied by a batch technique. The effects of pH, ionic strength, and humic substances on the adsorption of Am(III) on alumina and silica were investigated, and the adsorption isotherms of Am(III) on alumina and silica at different pH values were determined. It was found that compared with the adsorption of Am(III) on alumina, the adsorbability of silica on the basis of mass is less, the relative adsorption rate on silica is slower, the sensitivity of adsorption on silica to ionic strength is less, the dependence of adsorption on silica on pH is gentler, and consequently that the adsorption characteristics of Am(III) on alumina and silica are distinctly different. The negative effect of fulvic acid on the adsorption on silica and the positive effect of humic acid on the adsorption on alumina were found. In contrast to the Am(III) adsorption on alumina and silica, a tremendously high adsorbability of Am(III) on hematite was found. The sequence of adsorbabilities of Am(III) on the basis of mass is Fe2O3 > Al2O3 > SiO2. 相似文献
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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
20.
The mesoporous molecular sieves (Al-MCM-41) are synthesized with montmorillonite as silica–alumina source by hydrothermal
method. The application of Al-MCM-41 for the adsorption of Th(IV) from aqueous solution is studied by batch technique. The
effects of contact time, solid content, pH, ionic strength, foreign ions, and temperature are determined, and the results
indicate that the adsorption of Th(IV) to Al-MCM-41 is strongly dependent on pH values but independent of ionic strength.
The adsorption isotherms are simulated by D–R and Freundlich models well. The thermodynamic parameters (ΔH
0, ΔS
0, ΔG
0) are calculated from the temperature dependent adsorption isotherms at 293, 313 and 333 K, respectively, and the results
suggest that the adsorption of Th(IV) on Al-MCM-41 is a spontaneous and endothermic process. Al-MCM-41 is a suitable material
for the preconcentration of Th(IV) from large volumes of aqueous solutions. 相似文献