共查询到20条相似文献,搜索用时 15 毫秒
1.
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
2.
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
3.
Sorption of thorium (IV) on goethite was investigated as a function of contact time, pH, ionic strength, anions, solid-to-liquid
ratio (m/V) and Th(IV) concentration using batch technique. The results showed that the sorption of Th(IV) was strong pH-dependence,
and increased from ~10 to ~100% over the pH range of 2.0–4.0, and then kept a constant level in the higher pH range. The sorption
of Th(IV) increased with increasing m/V and independent of ionic strength. It was clear that phosphate and FA significantly enhanced Th(IV) sorption on goethite.
The sorption and desorption isotherms were investigated at pH 2.90 ± 0.05 and analyzed with Freundlich and Langmuir models,
respectively. Compared to Langmuir model, Freundlich model could fit the experimental data better, according to the high relative
coefficients. 相似文献
4.
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
5.
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
6.
Taisiya O. Kozlova Dr. Andrey V. Mironov Dr. Sergey Y. Istomin Karina V. Birichevskaya Prof. Andrey A. Gippius Dr. Sergey V. Zhurenko Dr. Tatyana B. Shatalova Dr. Alexander E. Baranchikov Prof. Vladimir K. Ivanov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(53):12188-12193
Two new cerium(IV) phosphates were obtained: cerium(IV) hydroxidophosphate, Ce(OH)PO4, and cerium(IV) oxidophosphate, Ce2O(PO4)2, which were shown to complement the classes of isostructural compounds M(OH)PO4 and R2O(PO4)2, where M=Th, U and R=Th, U, Np, Zr. Ce2O(PO4)2 oxidophosphate is formed by elimination of H2O from the crystal structure of Ce(OH)PO4 during its thermal decomposition. The structures of Ce(OH)PO4 and Ce2O(PO4)2 are related to each other with the same Cmce space group and similar unit cell parameters (a=6.9691(3) Å, b=9.0655(4) Å, c=12.2214(4) Å, V=772.13(8) Å3, Z=8; a=7.0220(4) Å, b=8.9894(5) Å, c=12.544(1) Å, V=791.8(1) Å3, Z=4, respectively). 相似文献
7.
Yan Li Chunli Wang Zhijun Guo Chunli Liu Wangsuo Wu 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(3):1683-1691
Graphene oxide (GO) is one of the most important carbon nano-materials. In this paper, GO was synthesized from flake graphite and characterized by transmission electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. The sorption of Th(IV) on GO was investigated as a function of contact time, solid-to-liquid ratio, pH, ionic strength, and in the presence of fulvic acid (FA) and humic acid (HA) by batch experiments. The sorption percentage of Th(IV) on GO decreased with increasing ionic strength and decreasing solid-to-liquid ratio. The sorption edge of Th(IV) in the presence of FA/HA is much lower than that in the absence of FA/HA. Furthermore, the sorption processes of Th(IV) can be described by a pseudo-second order rate model. Based on the Langmuir model, the maximum sorption capacities (Csmax) of Th(IV) were about 5.80 × 10?4 mol/L. From thermodynamic investigation, sorption of Th(IV) on GO is spontaneous and endothermic in nature. The rapid sorption rate and high sorption capacity suggest that GO is a promising adsorbent for Th(IV). 相似文献
8.
Lei Zhang Hongmei Li Xueyan Liu Pingli Kang 《Russian Journal of Inorganic Chemistry》2012,57(4):622-628
Titanium dioxide nanoparticles were employed for the sorption of Ge(IV) ions from aqueous solution. The process was studied
in detail by varying the sorption time, pH, and temperature. The sorption process was found to be fast, equilibrium was reached
within 3 min. A maximum sorption could be achieved from solution when the pH ranges between 4.0 and 11.0. Sorbed Ge(IV) ions
can be completely desorbed with 2 mL of 0.3 mol L−1 K3PO4-1.0 mol L−1 H2SO4 mixture solution. The kinetic experimental data properly correlate with the second-order kinetic model (k
2 = 0.88 g mg−1 min−1 (25°C)), Reichenberg equation and Morris-Weber model. The estimated E
a
for Ge(IV) adsorption on nano-TiO2 was 19.66 kJ mol−1. The overall rate process appears to be influenced by intra-particle diffusion. The sorption data could be well interpreted
with the Langmuir and Dubinin-Radushkevich (D-R) type sorption isotherms. The D-R parameters were calculated to be K = −0.00321 mol2 kJ−2, q
m
= 0.59 mmol g−1 and E = 12.48 kJ mol−1 at room temperature. Furthermore, the thermodynamic parameters were also determined, and the ΔH
0 and ΔG
0 values indicated a spontaneous exothermic behavior. 相似文献
9.
Sorption properties of oxides IX: Effect of anions on the sorption of uranium (VI) on hydrous oxides
Effect of anions such as nitrate, chloride, sulphate and carbonate on the sorption of U(VI), from aqueous solutions on hydrous
oxides of Ti(IV), Ce(IV) Zr(IV) and Th(IV) has been studied. The sorption of U(VI) is markedly reduced in the presence of
anions, like carbonate, whichform strong complexes with UO
2
2
+ in solution. The results are explained in terms of a competition for free UO
2
2
+ between surface hydroxyl groups and ligands (anions) present in solution. The sorption of U(VI) on these hydrous oxides was
also studied from a bicarbonatecarbonate mixture. Sorption was less under conditions when tricarbonate complex of U(VI) was
formed, but increased at higher pH values (>9), presumably due to the formation and sorption of hydroxo complexes of U(VI). 相似文献
10.
M. M. Godneva D. L. Motov M. P. Rys’kina 《Russian Journal of Inorganic Chemistry》2011,56(9):1363-1369
The ZrO(NO3)2-H3PO4-CsF-H2O system was studied at 20°C along the section at a molar ratio of PO43−/Zr = 0.5 (which is of the greatest interest in the context of phase formation) at ZrO2 concentrations in the initial solutions of 2–14 wt % and molar ratios of CsF: Zr = 1−6. The following compounds were isolated
for the first time: crystalline fluorophosphates CsZrF2PO4 · H2O, amorphous oxofluorophosphate Cs2Zr3O2F4(PO4)2 · 3H2O, and amorphous oxofluorophosphate nitrate CsZr3O1.25F4(PO4)2(NO3)0.5 · 4.5H2O. The compound Cs3Zr3O1.5F6(PO4)2 · 3H2O was also isolated, which forms in a crystalline or glassy form, depending on conditions. The formation of the following
new compounds was established: Cs2Zr3O1.5F5(PO4)2 · 2H2O, Cs2Zr3F2(PO4)4 · 4.5H2O, and Zr3O4(PO4)1.33 · 6H2O, which crystallize only in a mixture with known phases. All the compounds were studied by X-ray powder diffraction, crystal-optical,
thermal, and IR spectroscopic analyses. 相似文献
11.
Zhengjie Liu Lei Chen Yunhui Dong Zengchao Zhang 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(3):851-859
The sorption of Co(II) from aqueous solution on Na-rectorite was investigated under ambient conditions. Experiments were carried
out as a function of contact time, solid content, pH, ionic strength, foreign ions, fulvic acid and temperature. The results
indicated that the sorption of Co(II) was strongly dependent on pH. At low pH the sorption 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 Dubinin–Radushkevich (D–R) models were used to simulate the sorption isotherms at three different temperatures.
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 Na-rectorite was spontaneous and endothermic. Experimental results indicate that Na-rectorite is a suitable adsorbent
for preconcentration and solidification of Co(II) from large volumes of aqueous solutions. 相似文献
12.
Liqiang Tan Yeling Jin Xiaochun Cheng Jie Wu Wei Zhou Liangdong Feng 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(3):575-585
Batch sorption experiments were performed to remove Eu(III) ions from aqueous solutions by using attapulgite under ambient
conditions. Different experimental conditions, such as contact time, solid content, foreign ions, pH, ionic strength, fulvic
acid and temperature, have been investigated to study their effect on the sorption property. The results indicated that the
sorption of Eu(III) onto attapulgite was strongly dependent on pH, ionic strength and temperature. The sorption increased
from about 8.9 to 90% at pH ranging from 2 to 6 in 0.01 mol/L NaNO3 solution. The Eu(III) kinetic sorption on attapulgite was fitted by the pseudo-second-order model better than by the pseudo-first-order
model. The sorption of Eu(III) onto attapulgite increased with increasing temperature and decreasing ionic strength. The Langmuir
and Freundlich models were used to simulate the sorption isotherms, and the results indicated that the Freundlich model simulated
the data better than the Langmuir model. The thermodynamic parameters (∆G
o, ∆S
o, ∆H
o) were determined from the temperature dependent isotherms at 298.15, 318.15 and 338.15 K, and the results indicated that
the sorption reaction was an endothermic and spontaneous process. The results suggest that the attapulgite is a suitable material
as an adsorbent for preconcentration and immobilization of Eu(III) from aqueous solutions. 相似文献
13.
Ľ. Vrtoch M. Pipíška M. Horník J. Augustín J. Lesný 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(3):853-862
In order to gain biosorbent that would have the ability to bind cesium ions from water solution effectively, potassium nickel
hexacyanoferrate(II) (KNiFC) was incorporated into the mushroom biomass of Agaricus bisporus. Cesium sorption by KNIFC-modified A. bisporus biosorbent was observed in batch system, using radiotracer technique using 137Cs radioisotope. Kinetic study showed that the cesium sorption was quite rapid and sorption equilibrium was attained within
1 h. Sorption kinetics of cesium was well described by pseudo-second order kinetics. Sorption equilibrium was the best described
by Freundlich isotherm and the distribution coefficient was at interval 7,662–159 cm3 g−1. Cesium sorption depended on initial pH of solution. Cesium sorption was very low at pH0 1.0–3.0. At initial pH 11.0, maximum sorption of cesium was found. Negative effect of monovalent (K+, Na+, NH4
+) and divalent (Ca2+, Mg2+) cations on cesium sorption was observed. Desorption experiments showed that 0.1 M potassium chloride is the most suitable
desorption agent but the complete desorption of cesium ions from KNiFC-modifed biosorbent was not achieved. 相似文献
14.
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
15.
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
16.
M. M. Godneva V. Ya. Kuznetsov D. L. Motov M. P. Rys’kina O. A. Zalkind 《Russian Journal of Inorganic Chemistry》2009,54(12):2005-2009
We studied phase formation in the ZrO(NO3)2-H3PO4-RbF-H2O system along PO43−/Zr = 0.5 (mol/mol) and RbF/Zr = 1–5 (mol/mol) sections with 2–10 wt % ZrO2 in the starting solution. We recovered amorphous rubidium oxofluorophosphatozirconate Rb2Zr3OF6(PO4)2 · 2H2O and the following fluorophosphatonitratozirconates: Rb2ZrF4(PO4)0.33NO3, which forms large cubic system crystals; weakly crystallized RbZr3OF3(PO4)2(NO3)2 · 5H2O; and amorphous Zr3OF3(PO4)2NO3 · (7–8) H2O. A shown by its IR spectrum, Rb2ZrF4(PO4)0.33NO3 contains NO3- and PO4 groups that are not coordinated to zirconium, meaning that this is a triple salt ZrF4 · Rb(PO4)0.33 · RbNO3. The formula units of the RbZr3OF3(PO4)2(NO3)2 · 5H2O and Zr3OF3(PO4)2NO3 · (7–8)H2O phases are only conventional. All compounds have been recovered for the first time. 相似文献
17.
E. Yu. Borovikova V. S. Kurazhkovskaya D. M. Bykov A. I. Orlova 《Journal of Structural Chemistry》2010,51(1):40-44
Solid solutions of double orthophosphates of zirconium and rare earth lanthanum and ytterbium (La0.33Zr2(PO4)3-Yb0.33Zr2(PO4)3) that belong to the NASICON (NZP) structural type are synthesized and studied by IR spectroscopy. The factor-group analysis
of P-O vibrations in phosphates with P3 (La0.33Zr2(PO4)3) and P3c (Yb0.33Zr2(PO4)3) space groups allows us to assign the intermediate representatives of this series to two different space groups by their
IR spectra, which is difficult to perform based on powder X-ray diffraction results. A morphotropic transition P3 → P3 c is found to occur near the La1/18Yb5/18Zr2(PO4)3 composition. 相似文献
18.
Yuying Zhang Haogui Zhao Qiaohui Fan Xiaobei Zheng Ping Li Shengping Liu Wangsuo Wu 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(2):395-404
Sorption of U(VI) from aqueous solution to decarbonated calcareous soil (DCS) was studied under ambient conditions using batch
technique. Soil samples were characterized by XRD, FT-IR and SEM in detail and the effects of pH, solid-to-liquid ratio (m/V), temperature, contact time, fulvic acid (FA), CO2 and carbonates on U(VI) sorption to calcareous soil were also studied in detail using batch technique. The results from experimental
techniques showed that sorption of U(VI) on DCS was significantly influenced by pH values of the aqueous phase, indicating
a formation of inner-sphere complexes at solid–liquid interface, and increased with increasing temperature, suggesting the
sorption process was endothermic and spontaneous. Compared to Freundlich model, sorption of U(VI) to DCS was simulated better
with Langmuir model. The sorption equilibrium could be quickly achieved within 5 h, and sorption results fitted pseudo-second-order
model well. The presence of FA in sorption system enhanced U(VI) sorption at low pH and reduced U(VI) sorption at high pH
values. In absence of FA, the sorption of U(VI) onto DCS was an irreversible process, while the presence of FA reinforced
the U(VI) desorption process reversible. The presence of CO2 decreased U(VI) sorption largely at pH >8, which might due to a weakly adsorbable formation of Ca2UO2(CO3)3 complex in aqueous phase. 相似文献
19.
《Journal of Coordination Chemistry》2012,65(14):1583-1590
Thorium(IV) tetrakis(dithiophosphates), [Th{S2P(OR)2}4] (where R?=?–CH2CH2CH3 or –C6H5) and [Th{S2PO2G}4] [where G?=?–C(CH3)2CH2CH(CH3)–, –CH2C(CH3)2CH2–, –C(CH3)2C(CH3)2– and –CH2CH2CH(CH3)–] were prepared in methanolic solution of Th(NO3)4???6H2O and ammonium dithiophosphates. Adducts of the type [Th{S2P(OR)2}4???nL] and [Th{S2PO2G}4???nL] [where n?=?1, L?=?N2C10H8 or N2C12H8 and n?=?2, L?=?P(C6H5)3] were prepared by the reaction of thorium(IV) tetrakis(dithiophosphates) and nitrogen or phosphorus donors in benzene. These newly synthesised derivatives have been characterized by elemental analyses, molecular weights, IR, 1H and 31P NMR spectral measurements. Coordination numbers of eight and ten are suggested for thorium(IV) in these derivatives. 相似文献
20.
Francisco M. S. Garrido Oswaldo L. Alves 《Journal of Sol-Gel Science and Technology》1994,2(1-3):421-425
The NbZr(PO4)3 and Na0.5Nb0.5Zr1.5(PO4)3 Nasicon-like phases were prepared by the sol-gel method using (NH4)3 [NbO(C2O4)3]·1.5H2O, ZrOCl2·8H2O and NH4H2PO4 in oxalic or tartaric acid mediums. The thermal evolution of the xerogels prepared was followed by XRD and IR techniques. Depending on reaction conditions, such as, pH and Zr4+/organic acid ratio, pure Nasicon-like phases can be prepared at different temperatures. 相似文献