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1.
O. Rosskopfová M. Galamboš P. Rajec 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(3):601-606
The distribution of strontium between the milk components, i.e., serum, casein micelles, whey and hydroxyapatite was determined.
The sorption on hydroxyapatite was investigated using batch method and radiotracer technique. The aqueous phase comprised
of either milk or whey. The sorption of strontium on hydroxyapatite depended on the method of its preparation and on the composition
of the aqueous phase. The sorption of strontium was increased with an increase of pH. The presence of citrate species resulted
in decrease of the sorption of strontium on hydroxyapatite. The sorption of 85Sr on hydroxyapatite decreased with the increasing concentration of Ca2+ ions. Addition of Ca2+ ions to milk resulted in milk pH decrease. The decrease in pH value after calcium addition to milk is related to exchanges
between added calcium and micellar H+. The average value of strontium sorption on casein micelles in milk with presence of hydroxyapatite was (47.3 ± 5.6) %. The
average value of sorption of 85Sr on casein micelles in milk without the addition of hydroxyapatite was (68.9 ± 2.2) %. 相似文献
2.
O. Rosskopfová M. Galamboš L. Pivarčiová M. Čaplovičová P. Rajec 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):459-465
The sorption of nickel on synthetic hydroxyapatite was investigated using a batch method and radiotracer technique. The hydroxyapatite samples used in experiments were a commercial hydroxyapatite and hydroxyapatite of high crystallinity with Ca/P ratio of 1.563 and 1.688, respectively, prepared by a wet precipitation process. The sorption of nickel on hydroxyapatite was pH independent ranging from 4.5 to 6.5 as a result of buffering properties of hydroxyapatite. The adsorption of nickel was rapid and the percentage of Ni sorption on both samples of hydroxyapatite was >98 % during the first 15–30 min of the contact time for initial Ni2+ concentration of 1 × 10?4 mol dm?3. The experimental data for sorption of nickel have been interpreted in the term of Langmuir isotherm and the value of maximum sorption capacity of nickel on a commercial hydroxyapatite and hydroxyapatite prepared by wet precipitation process was calculated to be 0.184 and 0.247 mmol g?1, respectively. The sorption of Ni2+ ions was performed by ion-exchange with Ca2+ cations on the crystal surface of hydroxyapatite under experimental conditions. The competition effect of Co2+ and Fe2+ towards Ni2+ sorption was stronger than that of Ca2+ ions. NH4 + ions have no apparent effect on nickel sorption. 相似文献
3.
《印度化学会志》2021,98(11):100191
Hydroxyapatite is a versatile compound resembling natural bone mineral. HAP insinuates feasibility with substitution ensuing in its application in various fields. The properties of calcium and strontium are cognate and pose as a bone-seeking trace-element that accumulates in new trabecular bone. Strontium substituted hydroxyapatite, Ca9.5Sr0.5(OH)2(PO4)6, was synthesized using citric acid as fuel and calcined 900 °C. The as-prepared product notably was characterized by powder X-ray diffraction, Fourier - Transform Infrared spectroscopy and Scanning Electron Microscope along with Energy Dispersive Spectroscopy. FT-IR analysis exhibited stretching and bending vibrations of (PO4)3- and OH− groups along without any signal of carbonate group. Studies showed that product formed is strontium substituted hydroxyapatite, and calcination temperature plays an essential role in the formation of hydroxyapatite phase. The precursors when calcined resulted in 46–50 nm of Sr substituted hydroxyapatite. 相似文献
4.
D. K. Das P. N. Pathak S. Kumar V. K. Manchanda 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(3):449-455
Sorption behavior of 241Am (~10−9 M) on naturally occurring mineral pyrite (particle size: ≤70 μm) has been studied under varying conditions of pH (2–11),
and ionic strength (0.01–1.0 M (NaClO4)). The effects of humic acid (2 mg/L), other complexing anions (1 × 10−4 M CO3
2−, SO4
2−, C2O4
2− and PO4
3−), di- and trivalent metal ions (1 × 10−3 M Mg2+, Ca2+ and Nd3+) on sorption behavior of Am3+ at a fixed ionic strength (I = 0.10 M (NaClO4)) have been studied. The sorption of 241Am on pyrite increased with pH from 2.8 (84%) to 8.1 (97%). The sorption of 241Am decreased with ionic strength at low pH values (2 ≤ pH ≤ 4), but was insensitive in the pH range of 4–10, suggesting the
formation of outer-sphere complexes on pyrite surface at lower pH, and inner-sphere complexes at higher pH values. The sorption
of 241Am increased in the presence of (i) humic acid (5 < pH < 7.5), and (ii) C2O4
2− (2 < pH < 3). By contrast, other complexing anions such as (carbonate, phosphate, and sulphate) showed negligible influence
on 241Am sorption. The presence of Mg2+, Ca2+ ions showed marginal effect on the sorption profile of 241Am; while the presence of Nd3+ ion suppressed its sorption significantly under the conditions of present study. The sorption of 241Am on pyrite decreased with increased temperature indicating an exothermic process. 相似文献
5.
H. Göktürk C. Eylem S. Hatipoĝlu H. N. Erten 《Journal of Radioanalytical and Nuclear Chemistry》1995,198(2):449-456
The sorption behavior of strontium and barium on kaolinite, bentonite and chlorite-illite mixed clay was studied by radioanalytical techniques using the batch method.90Sr (29.1 y) and133Ba (10.5 y) were used as radiotracers. Characterization of the solid matrices was done by FTIR and XRD spectrometries and specific surface area measurements. Synthetic groundwater was used as the aqueous phase. The variation of the distribution ratioR
d, as a function of metal ion loading was examined. The sorption isotherms were fitted to various isotherm models. The sorption energies were calculated to be in the range of 8–10 kJ/mol suggesting an ion exchange type of sorption mechanism. In detailed experiments, chlorite-illite mixed clay was first presaturated with K+, Sr2+, Ca2+ and Al3+ ions, respectively, prior to sorption studies with Ba2+ ions. The results of Ca2+ pretreated chlorite-illite were very similar to those of natural chlorite-illite, suggesting that the Ba2+ ion exchanges primarily with the Ca2+ ion on the clay minerals. 相似文献
6.
M. Galamboš J. Kufčáková P. Rajec 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(3):347-357
Sorption of Sr on five Slovak bentonites of deposits has been studied with the use of batch technique. In the experiments
there have been used natural, chemically modified and irradiated samples, in three different kinds of grain size. The pH influence
on sorption of strontium on bentonites, pH change after sorption and influence of competitive ions have been studied. Distribution
ratios have been determined for bentonite–strontium solution system as a function of contact time, pH and sorbate concentration.
The data have been interpreted in term of Langmuir isotherm. The uptake of Sr has been rapid and the sorption of strontium
has increased by increasing pH. The percentage sorption has decreased with increasing metal concentrations. The pH value after
sorption for the natrificated forms of bentonite starts already in the alkaline area and moves to the higher values. For the
natural bentonites the values occur in the neutral or in the acidic area. Sorption of Sr has been suppressed by presence of
competitive cations as follows: Ba2+ > Ca2+ > Mg2+ > NH4
+ > K+ > Na+. By sorption on natrificated samples colloidal particles and pH value increase have been formed. The bentonite exposure as
a result of interaction of γ-rays has led to expansion of the specific surface, increasing of the sorption capacity and to
the change in the solubility of the clay materials. 相似文献
7.
Pingping Su Kim Granholm Andrey Pranovich Leo Harju Bjarne Holmbom Ari Ivaska 《Cellulose (London, England)》2010,17(5):1033-1044
Knowledge about how different metal ions are bound to pulp fibers is very important for optimal metal management in pulping
processes. A column chromatographic method was used to assess the differences in affinity of 14 metal ions to untreated, alkali-treated
and peroxide-bleached thermomechanical pulp (TMP). A method of competition between cations in the column chromatographic experiments
was used in the sorption experiments, with an excess of each metal ion compared to the total capacity of the pulp studied.
The method is very sensitive and even small differences in affinities can be detected. By combining the results from sorption
experiments with four different metal ion mixtures the following order of affinity was obtained: Pb2+ ≫ Cu2+ ≫ Cd2+ > Zn2+ > Ni2+ > Ba2+ > Ca2+ > Mn2+ > Sr2+ > Mg2+ ≫ Rb+ ≈ K+ > Na+ > Li+. All three types of pulps showed the same affinity order. Lead and copper ions were clearly most strongly bound to the pulp
fibers. Within the alkali and alkaline earth metal groups the differences in affinity were quite small. The sorption of metal
ions to pulp fibers takes place mainly by complexation, where the divalent metal ions are coordinated to functional groups
(acid groups) in the fiber phase. Protonation constants and concentrations of acid groups were determined by potentiometric
titration. A model with two carboxyl groups and two phenolic hydroxyl groups satisfied best the experimental data. By treatment
with alkali and peroxide new acid groups were created and the total binding capacity of hydrogen ions increased from 137 μeq/g
for untreated pulp to 187 and 228 μeq/g for alkali-treated and peroxide-treated pulp, respectively. 相似文献
8.
Sr-doped calcium phosphates have been prepared by sol–gel chemistry. All samples exhibit two phases: hydroxyapatite (HAp)
and tricalcium phosphate (β-TCP). With respect to undoped sample, the Sr-doped samples exhibit higher proportion of β-TCP
phase but the quantity appears to be quite independent of the doping level. To explain the mismatch with the nominal stoichiometry,
the presence of amorphous CaO and SrO compounds have been postulated and their proportions evaluated. The insertion of Sr2+ ions in the two crystalline phases HAp and β-TCP is almost total for low doping levels but quite incomplete for the highest
doping level. The majority of the inserted Sr2+ ions are in the β-TCP phase. Considering the acknowledged beneficial effect of Sr2+ on the bone regeneration process, the effective partial substitution of Sr in biphasic calcium phosphate makes these materials
very interesting for clinical applications.
The Sr-substituted HAp and β-TCP cell parameters agree fairly well with the Vegard’s law and Sr2+ ions substitute preferentially for Ca2+ in the Ca2 site for hydroxyapatite and in the Ca4 site for β-TCP. The microstructural parameters confirm the previous observation
and give a new evidence of clear stabilizing effect of Sr2+ ions towards the β-TCP structure. 相似文献
9.
M. T. Olguín I. García-Sosa M. Solache-Ríos 《Journal of Radioanalytical and Nuclear Chemistry》1996,204(2):415-422
The apparent diffusion coefficient of Sr2+ in natural Mexican erionite from Sonora at different pH and concentrations were determined. Neutron activation was applied to measure the sorption of strontium. The apparent diffusion coefficient values showed that the mobility of Sr2+ through the cavities of the erionite depended on the concentration of strontium and the pH of the solution. As a consequence the sorption of this ion by the erionite was affected by these parameters and the maximum sorption of Sr2+ was at pH higher than 3 and 0.0094 mol·l–1 strontium nitrate solution. 相似文献
10.
S. Pramanik S. S. Bhattacharyya P. Chattopadhyay 《Journal of Radioanalytical and Nuclear Chemistry》2007,274(2):237-243
A new stable chelating resin was synthesized by incorporating 2-aminothiophenol into Merrifield polymer through C-N covalent
bond and characterized by elemental analysis, IR and thermal study. The sorption capacity of the newly formed resin for Hg2+ as a function of pH has been studied using 203Hg radioisotope. The resin exhibits no affinity to alkali or alkaline earth metal ions and common anions. The separation of
mercury(II) in presence of different alkali and alkaline earth metal ions (Na+, K+, Mg2+, Ca2+, Sr2+, Ba2+), common anions (ClO4
−, SO4
2−) and other diverse ions (Ag+, Cu2+, Pb2+, Fe3+, Ni2+ and Zn2+) has been checked. In column operation it has been observed that Hg2+ content of the waste water can be removed at usual pH of natural water. Mercury was determined by isotope dilution method
and the concentration of Hg2+ in the waste water spiked with 203Hg was found to be 0.05 to 0.09 μg/ml. 相似文献
11.
Theodora J. Stewart Jean-Huei Yau Mary M. Allen Daniel J. Brabander Nolan T. Flynn 《Colloid and polymer science》2009,287(9):1033-1040
Chronic exposure to Pb2+ above the 15-μg/L US Environmental Protection Agency action level for drinking water has been shown to cause a host of health
problems in humans. Thus, it is important to study new methods available for the treatment and removal of Pb2+ from drinking water and wastewater, where elevated levels of heavy metals are found. Alginate-based beads represent one such
possible method for heavy metal removal. The impact of alginate density on the equilibrium and kinetics of Pb2+ sorption onto hydrogel beads was investigated using Ca-alginate beads ranging from 1% to 8% (w/v) and exposed to Pb2+ concentrations ranging from 100 to 1,000 mg/L. When Ca-alginate beads were characterized using Fourier transform infrared
analysis, the carboxylic acid groups of the mannuronate and guluronate residues in alginate were the primary functional groups
that interacted with Pb2+. Hydration of Ca-alginate beads was also examined and found to decrease as Ca-alginate density increased. A positive correlation
was observed between Ca-alginate hydration and Pb2+ sorption. Sorption of Pb2+ was fast, reaching equilibrium after approximately 4 h, and is well described by the Langmuir adsorption isotherm. Maximum
sorption capacities for 1%, 4%, and 8% beads were 500 ± 100, 360 ± 30, and 240 ± 20 mg/g (dry weight), respectively. The kinetics
of sorption were best described by the pseudo-second-order Lagergren model, with rate constants determined as 3.2 ± 0.1 × 10−4, 1.0 ± 0.1 × 10−4, and 1.6 ± 0.1 × 10−4 g mg−1 min−1 for 1%, 4%, and 8% beads, respectively. 相似文献
12.
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
13.
Z. Branković K. Đuriš A. Radojković S. Bernik Z. Jagličić M. Jagodič K. Vojisavljevic G. Branković 《Journal of Sol-Gel Science and Technology》2010,55(3):311-316
Substituted lanthanum manganites with the general formula A1−x
B
x
MnO3 (A = La, B = Ca, Sr…) have attracted a lot of attention due to their exceptional electric and magnetic properties. In this
work, pure and Ca2+, Sr2+-doped LaMnO3 (LMO) with the concentrations of dopants 30% Ca2+ (LCMO), 30% Sr2+ (LSMO) and 15% Ca2+ + 15% Sr2+ (LCSMO) (in mol. %) were synthesized by polymerizable complex method. Bulk samples were prepared by sintering at 1300 °C
for 4 h in oxygen atmosphere. It was found that sintering in oxygen atmosphere enables preparation of single phase ceramics
with rhombohedral crystal structure. Chemically prepared fine, submicronic precursor powders provided uniform microstructure
and grain size distribution in final ceramics. As a result, pure and doped LMO ceramics with excellent microstructural and
magnetic properties were obtained. Depending on the composition, magnetic measurements showed high saturation magnetizations
(up to 93 emu/g), with values of the Curie temperature in the range 180–390 K and magnetoresistance up to 67%. 相似文献
14.
Steffen Seitz Petra Spitzer Richard J. C. Brown 《Accreditation and quality assurance》2010,15(1):9-17
The first part of the study assessed the equivalence of practical salinity measurement results of a slightly diluted seawater
sample from the North Atlantic, which were traceable to the SI. The study shows that the practical salinity reference value
S
RV (here S
RV = 34.967) can be determined with a relative standard uncertainty of 3×10−4. This quantifies the uncertainty range, in which long-term comparability of practical salinity measurement results can be
guaranteed currently. In the second part of the study, eight laboratories determined the mass fractions of five seawater components
to quantify the equivalence of these measurement results. The results were: Na+ (10.726 ± 0.134) g/kg, Mg2+ (1.288 ± 0.018) g/kg, Sr2+ (0.00755 ± 0.00011) g/kg, Cl− (19.360 ± 0.047) g/kg, SO4
2− (2.650 ± 0.025) g/kg. The investigation confirmed the reference composition mass fractions of sodium, magnesium and chloride
ions, but it showed a disagreement for strontium and sulphate ions. 相似文献
15.
N. Mofaddel H. Krajian D. Villemin P. L. Desbène 《Analytical and bioanalytical chemistry》2009,393(5):1545-1554
The potentialities of new ionic liquids (ILs) based on choline were evaluated as an electrophoretic medium in capillary electrophoresis
for the analysis of alkaline and alkaline earth cations (Li+, K+, Na+, Cs+, Mg2+, Ba2+, Ca2+, and Sr2+) with indirect UV detection. Two types of capillaries were tested: an untreated fused silica and fused silica coated with
a film of polyvinylalcohol. The coated capillary proved to be the best adapted for the metal ions studied. Moreover, it appeared
that the nature of the ionic liquid anion influenced the baseline stability, and the bis(trifluoromethylsulfonyl) imide (NTf2
−) anion seemed to be the most efficient. These preliminary studies led us to synthesize a new ionic liquid, 2-hydroxy-N,N,N-trimethyl-1-phenylethanaminium NTf2 (phenylcholine NTf2). This liquid was able to act as the running electrolyte and probe, generating the background signal in indirect UV light
and consequently simplifying the electrophoretic medium. Excellent baseline stability, good reproducibility, as well as good
sensitivity of detection were obtained with this new ionic liquid. Thus, 510,000 plates/meter for Li+ with 40 mM IL were successfully obtained. The optimal concentration of IL was 20 mM with a detection limit ranging from 28 μg
L−1 for Li+ to 1,000 μg L−1 for Cs+. This method (phenylcholine NTf2 with polyvinylalcohol capillary) was applied to analyze different commercial source and mineral waters. Finally, the potentiality
of this ionic liquid in nonaqueous capillary electrophoresis was explored. The use of phenylcholine NTf2 with a fused silica capillary, in pure methanol medium and in the presence of acetic acid, made it possible to obtain separation
selectivity different from that obtained in aqueous medium. 相似文献
16.
Yifei Li Shuaihui Tian Tianwei Qian 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):337-343
Instead of radioactive 90Sr, common strontium chloride was used to simulate the migration of radioactive strontium chloride in surface hydroxylated,
silanized, and common quartz sand. The sorption and retardation characteristics of strontium (Sr2+) in these surface modified quartz sands were studied by batch tests and column experiments. The equilibrium sorption data
for Sr2+ on different wettability sands were described by the Langmuir and Freundlich isotherm models, and the Langmuir model has
been found to provide better correlation for hydrophilic sand. The breakthrough curves (BTCs) of Sr2+ in these media were analyzed with the equilibrium convection–dispersion equation (CDE) and a non-equilibrium two-region mobile–immobile
model (TRM) using a nonlinear least square curve-fitting program CXTFIT. The TRM model showed better fit to the measured BTCs
of Sr2+, and the parameters of the fraction of mobile water indicated that significant preferential flow effected the non-equilibrium
transport of Sr2+. Although TRM model could not fit the Sr2+ BTCs very well, the parameter estimated by TRM model may be more reliable than those obtained from batch experiments because
the transport of Sr2+ in these kind of sand is non-equilibrium processes. 相似文献
17.
Xie Hongqin Wu Duilin Jiao Zhe Li Xiaowei Zhang Shouwei Lan Yan Cheng Cheng 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(2):637-647
A novel composite adsorbent, magnetite/hydroxyapatite (Fe3O4/HAP) composites, was prepared by biowaste chicken eggshell for the purpose of removing radiocobalt from aqueous solutions.
It highlighted that more than 92% Co(II) could be removed by using the developed composites under the experimental conditions.
The maximum sorption capacity of Co(II) on Fe3O4/HAP composites was 6.9 × 10−4 mol/g. The coexisted foreign ions, e.g., ClO4
−, NO3
−, Cl−, Na+ and K+, did not interfere the elimination of Co(II) from aqueous solutions, while Mg2+ did. The sorption process was found to be controlled well by pseudo-second-order and intra-particle diffusion models, and
the equilibrium data were simulated by Langmuir model very well with high correlation coefficients. The thermodynamic parameters
confirmed the spontaneity and endothermic nature of Co(II) sorption processes. After sorption, the Fe3O4/HAP composites could be effectively and fleetly separated from aqueous solutions by magnetic separation technique in large
scale. The Fe3O4/HAP composites are suitable materials in the preconcentration of Co(II) from large volumes of aqueous solutions. 相似文献
18.
Ajay K. Jain Sushma Agrawal Raj P. Singh 《Journal of Radioanalytical and Nuclear Chemistry》1979,54(1-2):171-182
A new inorganic ion-exchanger, zirconium tugnstoarsenate, has been synthesized which has been characterized by chemical analysis,
thermogravimetry, X-ray and infrared spectroscopy. The ion exchanger has been found to be stable in acids and neutral salt
solutions. The Kd values for 30 metal ions have been determined at pH 3–4 which show that the exchanger has high affinity for UO
2
2+
, ZrO2+, Cs+ and Tl+ ions. The variation of Kd for a number of metal ions as a function of concentration of nitric acid and ammonium nitrate has been investigated to elucidate
the probable exchange mechanism and to work out conditions for elution. Some binary separations, viz. Sr2+−Cs+, Sr2+−Rb+, Sr2+−Y3+, Fe3+−Al3+, Fe3+−Zn2+ and Zn2+−Hg2+ in trace amounts have been carried out on the column of the exchanger which demonstrate the utility of the exchanger in radionalytical
and analytical chemistry. 相似文献
19.
The principles of selective separations by recrystallization are explained and formulae for the calculation of decontamination
factors are presented. Experiments with strontium sulfate and radioactive strontium ions demonstrate the validity of the theoretical
considerations. Similar or higher decontamination factors are found than those calculated for a uniform distribution of the
radioactive strontium ions between crystals and solution. The high values are explained by assuming a recrystallization mechanism
which consists of dissolution and redeposition of crystal layers. The half-times of recrystallization increase sharply with
Sr2+ or SO
4
2−
concentration in the solution. In nitric acid solutions as well as in mixtures containing nitrates and nitric acid the solubility
of strontium sulfate is rather high, accordingly the decontamination factors are low under these conditions and furthermore
the recrystallization half-times are long. 相似文献
20.
Sibel Kasap Huseyin Tel Sabriye Piskin 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):489-495
The objective of this study is to evaluate the use of titanium dioxide nanoparticles which were prepared by novel sonochemical
method as an ion exchange material for the removal of Sr from aqueous solution. The pH effect on the Sr2+ sorption was investigated. The data obtained have been correlated with Freundlich, Temkin and Dubinin–Radushkevich (D–R)
isotherm models. Thermodynamic parameters fort he sorption system have been determined at four temperatures. Simple kinetic
models have been applied to the rate and isotherm sorption data and the relevant kinetic parameters were determined from the
graphical presentation of these models at 298°K. Results explained that the pseudo second-order sorption mechanism is predominant
and the overall rate constant of sorption process appears to be controlled by chemical sorption process. The value of sorption
energy E = 13 kJ/mol at 298°K and the value of Gibbs free energy ∆G° = 3,222 kJ/mol at 298°K prove that the sorption of strontium on titanium dioxide nanoparticles is an endothermic and non-spontaneous
process. 相似文献