共查询到20条相似文献,搜索用时 31 毫秒
1.
Xiaoping Song Yajie Wang Jingjing Cai 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(2):991-1000
Bentonite has been studied extensively because of its strong sorption and complexation ability. In this study, GMZ bentonite (China) was studied as a potential sorbent for the removal of Th(IV) from aqueous solutions. The results indicate that the sorption of Th(IV) is strongly dependent on pH and ionic strength at pH <5, and is independent of ionic strength at pH >5. Outer-sphere surface complexation or ion exchange in inter-layer sites of the montmorillonite fraction of the GMZ bentonite may be the main sorption mechanism of Th(IV) onto 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. The presence of soil fulvic acid has a positive influence on the sorption of Th(IV) on GMZ bentonite at pH <5. The competition between Th(IV) with aqueous or surface adsorbed cation ions (e.g., herein Li+, Na+ and K+) and surface functional groups of GMZ bentonite is important for Th(IV) sorption on GMZ bentonite. The results of high sorption of Th(IV) suggest that the GMZ bentonite is a suitable backfill material in nuclear waste management. 相似文献
2.
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
3.
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
4.
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
5.
Songsheng Lu Zhiqiang Guo Caicai Zhang Shouwei Zhang 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(2):621-628
MX-80 bentonite was characterized by XRD and FTIR in detail. The sorption of Th(IV) on MX-80 bentonite was studied as a function
of pH and ionic strength in the presence and absence of humic acid/fulvic acid. The results indicate that the sorption of
Th(IV) on MX-80 bentonite increases from 0 to 95% at pH range of 0–4, and then maintains high level with increasing pH values.
The sorption of Th(IV) on bentonite decreases with increasing ionic strength. The diffusion layer model (DLM) is applied to
simulate the sorption of Th(IV) with the aid of FITEQL 3.1 mode. The species of Th(IV) adsorbed on bare MX-80 bentonite are
consisted of “strong” species
o \textYOHTh4 + \equiv {\text{YOHTh}}^{4 + } at low pH and “weak” species
o \textXOTh(OH)3 \equiv {\text{XOTh(OH)}}_{3} at pH > 4. On HA bound MX-80 bentonite, the species of Th(IV) adsorbed on HA-bentonite hybrids are mainly consisted of
o \textYOThL3 \equiv {\text{YOThL}}_{3} and
o \textXOThL1 \equiv {\text{XOThL}}_{1} at pH < 4, and
o \textXOTh(OH)3 \equiv {\text{XOTh(OH)}}_{3} at pH > 4. Similar species of Th(IV) adsorbed on FA bound MX-80 bentonite are observed as on FA bound MX-80 bentonite. The
sorption isotherm is simulated by Langmuir, Freundlich and Dubinin–Radushkevich (D–R) models, respectively. The sorption mechanism
of Th(IV) on MX-80 bentonite is discussed in detail. 相似文献
6.
Liang Chen Shaoming Yu Liming Zuo Bin Liu Lingli Huang 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):511-520
In this study, a local bentonite from Gaomiaozi county (Inner Mongolia, China) was converted to Na-bentonite and was characterized
by FTIR and XRD to determine its chemical constituents and micro-structure. The removal of cobalt from aqueous solutions by
Na-bentonite was investigated as a function of contact time, pH, ionic strength, foreign ions and temperature by batch technique
under ambient conditions. The results indicated that the sorption of Co(II) was strongly dependent on pH. At low pH, the sorption
of Co(II) was dominated by outer-sphere surface complexation or ion exchange whereas inner-sphere surface complexation was
the main sorption mechanism at high pH. The Langmuir, Freundlich, and D-R models were used to simulate the sorption isotherms
of Co(II) at the temperatures of 293.15, 313.15 and 333.15 K, respectively. The thermodynamic parameters (∆G°, ∆S°, ∆H°) of Co(II) sorption on GMZ bentonite calculated from the temperature-dependent sorption isotherms indicated that the sorption
of Co(II) on GMZ bentonite was an exothermic and spontaneous process. The Na-bentonite is a suitable material for the preconcentration
and solidification of Co(II) from aqueous solutions. 相似文献
7.
Tanveer Hussain Bokhari A. Mushtaq Islam Ullah Khan 《Journal of Radioanalytical and Nuclear Chemistry》2010,285(2):389-398
In this work, sorption of Ni(II) from aqueous solution to goethite as a function of various water quality parameters and temperature
was investigated. The results indicated that the pseudo-second-order rate equation fitted the kinetic sorption well. The sorption
of Ni(II) to goethite was strongly dependent on pH and ionic strength. A positive effect of HA/FA on Ni(II) sorption was found
at pH < 8.0, whereas a negative effect was observed at pH > 8.0. The Langmuir, Freundlich, and D-R models were applied to
simulate the sorption isotherms at three different temperatures of 293.15 K, 313.15 K and 333.15 K. The thermodynamic parameters
(ΔH
0, ΔS
0 and ΔG
0) were calculated from the temperature dependent sorption, and the results indicated that the sorption was endothermic and
spontaneous. At low pH, the sorption of Ni(II) was dominated by outer-sphere surface complexation or ion exchange with Na+/H+ on goethite surfaces, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. 相似文献
8.
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
9.
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
10.
Liang Chen Shaoming Yu Lingli Huang Gang Wang 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(3):1181-1191
The sorption of radionuclide 63Ni(II) on bentonite/iron oxide magnetic composites was investigated by batch technique under ambient conditions. The effect
of contact time, solid content, pH, coexistent electrolyte ions, fulvic acid, and temperature on Ni(II) sorption to bentonite/iron
oxide magnetic composites was examined. The results demonstrated that the sorption of Ni(II) was strongly dependent on pH
and ionic strength at pH <8.0, and was independent of pH and ionic strength at high pH values. The sorption of Ni(II) was
dominated by outer-sphere surface complexation or ion exchange at low pH, whereas inner-sphere surface complexation was the
main sorption mechanism at high pH. The experimental data were well fitted by Langmuir model. The thermodynamic parameters
(∆G°, ∆S°, ∆H°) calculated from the temperature-dependent sorption isotherms indicated that the sorption of Ni(II) on bentonite/iron oxide
magnetic composites was an endothermic and spontaneous processes. The results show that bentonite/iron oxide magnetic composites
are promising magnetic materials for the preconcentration and separation of radionickel from aqueous solutions in environmental
pollution. 相似文献
11.
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
12.
Zhiqiang Guo Donglin Zhao Yuan Li Zhesheng Chen Haihong Niu Jinzhang Xu 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(3):829-837
The sorption of radiocadmium on Ca-montmorillonite as a function of contact time, pH, ionic strength, foreign ions, humic acid (HA) and fulvic acid (FA) was studied using batch technique. The results demonstrated that the sorption of Cd(II) was dependent on ionic strength at pH < 9, and was independent of ionic strength at pH > 9. Outer-sphere surface complexation and/or ion exchange were the main mechanism of Cd(II) sorption on Ca-montmorillonite at low pH, whereas the sorption at high pH was mainly dominated via inner-sphere surface complexation. The sorption of Cd(II) on Ca-montmorillonite was dependent on foreign ions at low pH values, but was independent of foreign ions at high pH values. A positive effect of HA/FA on Cd(II) sorption was found at low pH values, whereas a negative effect was observed at high pH values. The thermodynamic parameters (i.e., ??H 0, ??S 0, ??G 0) were calculated from the temperature dependent sorption isotherms, and the results indicated that the sorption process of Cd(II) on Ca-montmorillonite was spontaneous and endothermic. 相似文献
13.
Zhiqiang Guo Dapeng Xu Donglin Zhao Shouwei Zhang Jinzhang Xu 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(2):505-512
This work contributed to the adsorption of radiocobalt on goethite as a function of contact time, pH, ionic strength and foreign
ions in the absence and presence of fulvic acid (FA) under ambient conditions. The results indicated that adsorption of Co(II)
was dependent on ionic strength and foreign ions at low pH values (pH < 7.8), and independent of ionic strength and foreign
ions at high pH values (pH > 7.8). Outer-sphere surface complexation and/or ion exchange were the main mechanisms of Co(II)
adsorption on goethite at low pH values, whereas inner-sphere surface complexation was the main adsorption mechanism at high
pH values. The presence of FA enhanced Co(II) adsorption at low pH values, but reduced Co(II) adsorption at high pH values.
The thermodynamic data (ΔH
0, ΔS
0, ΔG
0) were calculated from the temperature dependent adsorption isotherms, and the results suggested that adsorption process of
Co(II) on goethite was spontaneous and endothermic. The results are crucial to understand the physicochemical behavior of
Co(II) in the nature environment. 相似文献
14.
The ammonium citrate tribasic was successfully modified to attapulgite clay and the effect of modifying was characterized
by FTIR and XRD techniques. Experimental results showed that the ammonium citrate tribasic modified attapulgite clay had a
strong sorption ability to remove Th(IV) from aqueous solutions. The sorption of Th(IV) from aqueous solutions has been systematically
investigated as a function of several variables including contact time, solid content, pH, ionic strength, Fulvic acid (FA)/humic
acid (HA) and temperature under ambient conditions. The results indicate that the sorption of Th(IV) onto ammonium citrate
tribasic modified attapulgite clay is strongly dependent on pH, Th(IV) initial concentration, ionic strength, temperature
and HA/FA. Surface complexation and ionic exchange are the main sorption mechanisms. Sorption of Th(IV) onto ammonium citrate
tribasic modified attapulgite is quick and can be fitted by a pseudo-second-order rate model very well. Sorption of Th(IV)
onto ammonium citrate tribasic modified attapulgite is promoted at higher temperature and the sorption reaction is an endothermic
process. Langmuir isotherm model fits the experimental data better than Freundlich and D-R isotherm models. The results suggest
that the ammonium citrate tribasic modified attapulgite sample is a suitable material in the preconcentration and solidification
of radionuclide Th(IV) from large volumes of aqueous solutions. 相似文献
15.
Lei Chen Bin Gao Songsheng Lu Yunhui Dong 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(3):851-858
Sorption of radionickel on attapulgite is studied as a function of contact time, ionic strength, pH and temperature. The results indicate that the sorption of Ni(II) on attapulgite is strongly ionic strength-dependent at pH <8, and independent of ionic strength at pH >8. Outer-sphere surface complexation or ion exchange contributes to Ni(II) sorption on attapulgite at pH <8, whereas the sorption of Ni(II) is mainly dominated by inner-sphere surface complexation at pH >8. The sorption of Ni(II) on attapulgite increases with increasing temperature, and the thermodynamic parameters (??H 0, ??G 0 and ??S 0) calculated from the temperature dependent sorption isotherms suggest that the sorption of Ni(II) on attapulgite is a spontaneous and endothermic process. The high sorption capacity of attapulgite suggests that attapulgite is a suitable material for the preconcentration and solidification of radionickel from large volumes of aqueous solutions. 相似文献
16.
Keliang Shi Yuanlv Ye Ning Guo Zhijun Guo Wangsuo Wu 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(1):583-589
Bentonite has been studied extensively because of its strong sorption and complexation ability. In this work, the sorption of Se(IV) on purified GMZ bentonite was investigated under ambient temperature as functions of contact time, pH, Se(IV) concentration and co-existing ion Eu(III) using batch techniques. Sorption kinetics of Se(IV) was successfully described by the pseudo-second-order rate equation. The sorption amount of Se(IV) was strongly dependent on the solution pH, and a positive effect was observed on Se(IV) and Eu(III) co-sorption when these two elements existed in the same system under high surface coverage of sorbent. Double layer model was set up and used to quantitatively interpret the sorption experimental data collected in binary and ternary sorption systems. From the experimental results, one can conclude that GMZ bentonite may have good potentialities for immobilizing selenium in nuclear wastes. 相似文献
17.
Hui Zhang Lei Chen Lipeng Zhang Xianjin Yu 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(1):357-365
In this work, adsorption of Ni(II) from aqueous solution onto hematite under various solution chemistry and temperature was
investigated. The results indicated that the pseudo-second-order rate equation fitted the kinetic adsorption well. The adsorption
of Ni(II) onto hematite was strongly dependent on pH and ionic strength. At low pH, the adsorption was dominated by outer-sphere
surface complexation or ion exchange, whereas inner-sphere surface complexation was the main adsorption mechanism at high
pH. A positive effect of FA on Ni(II) adsorption was found at pH < 8.0, whereas a negative effect was observed at pH > 8.0.
The Langmuir, Freundlich, and D–R models were applied to simulate the adsorption isotherms at three different temperatures
of 293.15, 313.15 and 333.15 K. The thermodynamic parameters were calculated from the temperature dependent adsorption, and
the results indicated that the adsorption was endothermic and spontaneous. 相似文献
18.
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
19.
Jian-Hui Chen Ding-Qiang Lu Bin Chen Ping-Kai OuYang 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(3):2233-2241
In this paper, the multiwalled carbon nanotubes (MWCNTs) were modified with chitosan (CS) by using low temperature plasma grafting technique (denoted as MWCNT-CS). The prepared MWCNTs and MWCNT-CS were characterized by SEM, TEM, FTIR and Raman spectroscopy in detail and the results suggested that CS molecules were successfully grafted on the surfaces of MWCNTs. The materials were applied as adsorbents in the removal of U(VI) ions from large volumes of aqueous solutions as a function of environmental conditions. The removal of U(VI) from aqueous solution to MWCNTs and MWCNT-CS increased with increasing pH values at pH < 7, and then decreased with increasing pH values at pH > 7. The sorption of U(VI) on MWCNTs and MWCNT-CS was strongly dependent on pH and independent of ionic strength. The sorption of U(VI) on MWCNTs and MWCNT-CS was dominated by inner-sphere surface complexation rather than by ion exchange or outer-sphere surface complexation. The surface grafted chitosan molecules can enhances U(VI) sorption on MWCNTs obviously, which was also evidenced from the XPS spectroscopy analysis. The results of high sorption capacity of U(VI) on MWCNT-CS suggest that the MWCNT-CS nanomaterial is a suitable candidate in the preconcentration of U(VI) ions from large volumes of aqueous solutions. 相似文献
20.
Liqiang Tan Yeling Jin Jing Chen Xiaochun Cheng Jie Wu Liangdong Feng 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):601-610
The sorption of Co(II) on Na-attapulgite as a function of contact time, solid content, pH, ionic strength, foreign ions, fulvic
acid (FA) and temperature under ambient conditions was studied. The kinetic of Co(II) sorption on Na-attapulgite was described
well by pseudo-second-order model. The sorption of Co(II) on Na-attapulgite was strongly dependent on pH and ionic strength.
The sorption of Co(II) was mainly dominated by outer-sphere surface complexation and/or ion exchange at low pH, whereas inner-sphere
surface complexation or surface precipitation was the main sorption mechanism at high pH values. The presence of FA did not
affect Co(II) sorption obviously at pH <7, and a negative effect was observed at pH >7. The Langmuir and Freundlich models
were used to simulate the sorption data at different temperatures, and the results indicated that the Langmuir model simulated
the data better than the Freundlich isotherm model. The thermodynamic parameters (∆G°, ∆S°,
∆H°) calculated from the temperature-dependent sorption isotherms indicated that the sorption of Co(II) on Na-attapulgite was
an endothermic and spontaneous process. The results suggest that the attapulgite sample is a suitable material in the preconcentration
and solidification of radiocobalt from large volumes of aqueous solutions. 相似文献