共查询到20条相似文献,搜索用时 15 毫秒
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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
3.
In this work, a series of batch experiments were carried out to investigate the effect of various environmental factors such
as contact time, pH, ionic strength, coexisting electrolyte ions, humic substances and temperature on the sorption behavior
of illite towards 64Cu(II). The results indicated that 64Cu(II) sorption on illite achieved equilibrium quickly. The pH- and ionic strength-dependent sorption suggested that 64Cu(II) sorption on illite was dominated by ion exchange or outer-sphere surface complexation at pH < 7, whereas the pH-dependent
and ionic strength-independent sorption indicated that the sorption process was mainly attributed to inner-sphere surface
complexation at pH > 7. A positive effect of humic substances on 64Cu(II) sorption was found at pH < 6.5, whereas a negative effect was observed at pH > 6.5. The Langmuir and Freundlich models
were used to simulate the sorption isotherms of 64Cu(II) at three different temperatures of 293, 313, and 333 K. The thermodynamic parameters (ΔH
0, ΔS
0, and ΔG
0) of 64Cu(II) sorption on illite were calculated from the temperature dependent sorption isotherms, and the results indicated that
the sorption of 64Cu(II) on illite was endothermic and spontaneous. From the experimental results, it is possible to conclude that illite has
good potentialities for cost-effective treatments of 64Cu(II)-contaminated wastewaters. 相似文献
4.
Lipeng Zhang Hui Zhang Zhiwei Ge Xianjin Yu 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(2):537-546
The fate and transport of toxic metal ions and radionuclides in the environment is generally controlled by sorption reactions.
The removal of 60Co(II) from wastewaters by MnO2 was studied as a function of various environmental parameters such as shaking time, pH, ionic strength, foreign ions, and
humic substances under ambient conditions. The results indicated that the sorption of 60Co(II) on MnO2 was strongly dependent on pH and ionic strength. At low pH, the sorption of 60Co(II) was dominated by outer-sphere surface complexation and ion exchange with Na+/H+ on MnO2 surfaces, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. The presence of HA/FA enhances
60Co(II) sorption at low pH values, whereas reduces 60Co(II) sorption at high pH values. The Langmuir and Freundlich models were used to simulate the sorption isotherms of 60Co(II) at three different temperatures of 298.15, 318.15 and 338.15 K. The thermodynamic parameters (ΔH
0, ΔS
0 and ΔG
0) calculated from the temperature dependent sorption isotherms indicated that the sorption process of 60Co(II) on MnO2 was endothermic and spontaneous. 相似文献
5.
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
6.
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
7.
Hui Zhang Xianjin Yu Lei Chen Jiaqiang Geng 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(1):249-258
The sorption of 63Ni(II) from aqueous solution using ZSM-5 zeolite was investigated by batch technique under ambient conditions. ZSM-5 zeolite
was characterized by point of zero net proton charge (PZNPC) titration. The sorption was investigated as a function of shaking
time, pH, ionic strength, foreign ions, humic acid (HA), fulvic acid (FA) and temperature. The results indicate that the sorption
of 63Ni(II) on ZSM-5 zeolite is strongly dependent on pH. The sorption is dependent on ionic strength at low pH, but independent
of ionic strength at high pH values. The presence of HA/FA enhances 63Ni(II) sorption at low pH values, whereas reduces 63Ni(II) sorption at high pH values. The sorption isotherms are simulated by Langmuir model very well. The thermodynamic parameters
(i.e., ∆H
0, ∆S
0 and ∆G
0) for the sorption of 63Ni(II) are determined from the temperature dependent sorption isotherms at 293.15, 313.15 and 333.15 K, respectively, and
the results indicate that the sorption process of 63Ni(II) on ZSM-5 zeolite is spontaneous and endothermic. 相似文献
8.
Sorption of tracer Am3+ to silicate particles was studied as a function of pcH (4 to 9) and of ionic strength [0.20M to 1.50M (NaClO4)] at 298 K. The sorption increased with increased pcH from 4 to 6 above which saturation was observed. The insensitivity
of Am3+ sorption to increased ionic strength indicates inner-sphere complexation with the surface silicate sites. The effects of
different complexing anions such as carbonate, acetate, oxalate, phosphate, citrate, EDTA and humic acid, on Am3+ sorption were investigated. Synergistic enhancement in Am3+ sorption was observed in the presence of phosphate (4≤pcH≤7) and acetate (4≤pcH≤5) ligands at 0.20M NaClO4. The presence of the other ligands inhibited Am3+ sorption in the order: EDTA > citrate > oxalate > carbonate. Am3+ sorption in the presence of HA (25.00 mg/l) increased in the pcH range of 4.0 to 5.5, then decreased. Increased ionic strength
enhanced Am3+ sorption in the presence of 25.00 mg/l HA for 4≤pcH≤9. The sorption increased in the presence of a mixture of HA (25.00 mg/l)
and phosphate (1.00·10−3M) as compared to that of HA (25.00 mg/l) alone. The presence of Fe3+ (1.00·10−4M) enhanced Am3+ sorption at pcH∼4 but suppressed it from pcH of 5 to 9; 1.00·10−4M of Ca2+ and of UO22+ ions had no effect on the sorption profile.
On leave from Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai -400 085, India. 相似文献
9.
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
10.
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
11.
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
12.
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
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Different kinds of clay minerals have been studied extensively in the removal of radionuclides from large volumes of aqueous solutions because of their high sorption capacity. Herein, the Na-montmorillonite was characterized by using XRD and FTIR in detail. The sorption of 63Ni(II) from aqueous solution to montmorillonite as a function of pH, ionic strength, foreign ions, humic substances and temperature was studied by batch technique. The sorption of 63Ni(II) on montmorillonite achieved equilibration quickly. The sorption of 63Ni(II) to montmorillonite was strongly dependent on pH, and dependent on ionic strength at low pH and independent of ionic strength at high pH values. The sorption of 63Ni(II) on montmorillonite was enhanced at low pH in the presence of humic acid (HA), while a negative effect of HA on 63Ni(II) sorption was found at high pH values. At low pH values, the sorption of 63Ni(II) was attributed to outer-sphere surface complexation or ion exchange, whereas the sorption was dominated by inner-sphere surface complexation at high pH values. The montmorillonite sample is a suitable material in the preconcentration of radionuclides from large volumes and the material can be used as backfill material in nuclear waste repository. 相似文献
16.
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
17.
S. Kumar N. Rawat B. S. Tomar V. K. Manchanda S. Ramanathan 《Journal of Radioanalytical and Nuclear Chemistry》2007,274(2):229-231
Sorption of technetium on hematite colloids, at varying pH (3–10), has been studied in absence and presence of humic acid
using 95mTc-96Tc radiotracers. Technetium was found to be weakly sorbed on hematite at lower pH (<5) values, while no sorption was observed
at higher pH values. Humic acid was found to have no effect on the sorption of technetium on hematite under aerobic conditions,
while at lower pH values small reduction was observed which was attributed to the reduced zeta potential of the hematite colloids
owing to the strong sorption of humic acid. 相似文献
18.
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
19.
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