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1.
N. Doca Gabriela Vlase T. Vlase G. Ilia 《Journal of Thermal Analysis and Calorimetry》2008,94(2):441-445
The thermal behavior of Cd2+ and Co2+ phenyl-vinyl-phosphonates was studied using two different experimental strategies: the coupled TG-EGA (FTIR) technique by
decomposition in nitrogen respectively air, and the kinetic analysis of TG data obtained in dynamic air atmosphere at four
heating rates. In nitrogen two decomposition steps were observed: the loss of crystallization water, respectively the decomposition
of the phenyl-vinyl radical. In air, the same dehydration was observed as the first step, but the second one is a thermooxidation
of the organic radical with formation of the pyrophosphoric anion.
The kinetic analysis of the TG non-isothermal data was performed by the isoconversional methods suggested by Friedman and
Flynn, Wall and Ozawa, as well as by the non-parametric (Sempere-Nomen) method. All processes put in evidence in TG curves
exhibit strong changes of the activation energy values with the conversion degree, which mean that these processes are complex
ones. Assuming that each of these processes consists in two steps, the application of non-parametric method leads to average
values of the activation energy close to the average values of this parameter obtained by isoconversional methods. 相似文献
2.
Nizam M. El-Ashgar Issa M. El-Nahhal Mohamed M. Chehimi Michel Delamar Florence Babonneau Jacques Livage 《Journal of Sol-Gel Science and Technology》2007,41(1):3-10
A new insoluble solid functionalized ligand system bearing chelating ligand group of the general formula P-(CH2)3-N[CH2CONH(C6H4)NH2]2, where P represents [Si–O]
n
polysiloxane network, was prepared by the reaction of the immobilized diethyliminodiacetate polysiloxane ligand system, P-(CH2)3N(CH2CO2Et)2 with 1,2-diaminobenzene in toluene. 13C CP-MAS NMR, XPS and FTIR results showed that most ethylacetate groups (–COOEt) were converted into the amide groups (–N–C=O).
The new functionalized ligand system exhibits high capacity for extraction and removal of the metal ions (Fe3+, Co2+, Ni2+, Cu2+ and Zn2+) with efficiency of 95–97% after recovery from its primary metal complexes. This functionalized ligand system formed 1:1
metal to ligand complexes. 相似文献
3.
Isothermal titration calorimetry has been used to determine the stoichiometry, formation constants and thermodynamic parameters
(ΔG
o, ΔH, ΔS) for the formation of the citrate complexes with the Mn2+, Co2+, Ni2+ and Zn2+ ions. The measurements were run in Cacodylate, Pipes and Mes buffer solutions with a pH of 6, at 298.15 K. A constant ionic
strength of 100 mM was maintained with NaClO4. The influence of a metal ion on its interaction energy with the citrate ions and the stability of the resulting complexes
have been discussed. 相似文献
4.
E. Makrlík J. Budka P. Vaňura P. Selucký 《Journal of Radioanalytical and Nuclear Chemistry》2008,277(2):487-490
From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium
M2+(aq)+SrL2+(nb)⇔ML2+(nb)+Sr2+(aq) taking place in the two-phase water-nitrobenzene system (M2+ = Ba2+, Pb2+, Cd2+; L = tetramethyl p-tert-butylcalix[4]arene tetraketone; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Moreover, the stability constants
of the ML2+ complexes in water saturated nitrobenzene were calculated; they were found to increase in the order Ba2+<Cd2+<Pb2+. 相似文献
5.
Feather fibers were modified by treatment with 5% tannic acid (TA) solution. Kinetics of the modification was investigated
as a function of the reaction time. The maximum loading of TA on feather reached 8.3% after being treated by TA for 9 h. The
adsorption of metal cations (Cu2+, Zn2+) by unmodified and TA-modified feather fibers was investigated as a function of fiber weight gain, temperature, and pH of
the metal solution. The adsorption was enhanced at alkaline pH and ambient temperature and increased with the weight gain
of TA. The maximum uptake of metal cations (Cu2+, 0.77 mmol/g; Zn2+, 0.95 mmol/g) was obtained by TA-modified feather at weight gain: 8.3%, pH 11, while at the acidic pH, the adsorption of
metal cations by either unmodified or TA-modified feather was negligible. The influence of anions on the adsorption of metal
cations was also studied. The uptake of Cu2+ from chloride was higher and faster than that from nitrate. Desorption of the metals was performed at acidic pH 2.5 for 48 h.
The feather–TA–metal complexes exhibited higher stability for metal cations than the feather–metal complexes. All these experiments
reveal that TA-modified feather fibers have good adsorption to metal cations and can be used as metal adsorbent in wastewater
treatment. 相似文献
6.
Karin Popa Alexandru Cecal Doina Humelnicu Ioan Caraus Camelia L. Draghici 《Central European Journal of Chemistry》2004,2(3):434-445
This study concerns the removal of the 137Cs+ and 60Co2+ β+γ-radioactive ions in Azolla caroliniana Willd. water fern. The living fern and two different types of biosorbent prepared from Azolla caroliniana were tested to remove the above-mentioned radioactive ions from dilute solutions, in the absence and in the presence of the
ionic competition. Effective 137Cs+ and 60Co2+ ions removal from low radioactive wastewaters was demonstrated. The time dependent K
d
(t) values were calculated from the absorption data. These results indicate that removal process achieved equilibrium in about
120 min and that it involves two steps: rapid and slow absorption; the active process (metabolic bioaccumulation on the living
fern) was responsible for above one half of the total removal process. A thin layer radiochromatography study leads to the
conclusion that the biochemical components in which 137Cs+ and 60Co2+ place themselves are of a polysaccharide and lipoid fractions. 相似文献
7.
T. I. Chankina V. I. Parfenyuk 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(5):735-738
The standard real and chemical thermodynamic characteristics of transfer of the K+, Ca2+, Cd2+, and Br? ions from water into water-acetone solvents of various compositions were analyzed to study the rules governing the solvation of these ions in mixed solvents and its special features. All calculations were performed within the framework of the vertical jet method at 298.15 K. The energy of resolvation as a function of ion charges and crystallographic radii was found to increase in the series K+ < Ca2+ < Cd2+ < Al3+ 相似文献
8.
N. V. Shul’ga I. L. Shashkova N. V. Mil’vit A. I. Rat’ko 《Russian Journal of Applied Chemistry》2007,80(8):1304-1308
Kinetic characteristics of the interaction of trisubstituted calcium phosphate Ca3(PO4)2 · xH2O with Cu2+, Zn2+, Co2+, and Pb2+ ions in aqueous solutions were studied. 相似文献
9.
The efficiency of calcium and magnesium phosphates of different compositions in the extraction of Cu2+, Zn2, and Co2+ ions from aqueous solutions was studied. 相似文献
10.
Bin Peng Hui Chao Bin Sun Feng Gao Liang-Nian Ji Jian Zhang 《Transition Metal Chemistry》2007,32(2):271-277
Two novel cobalt(III) mixed-polypyridyl complexes
[Co(bpy)2(dpta)]3+ and [Co(bpy)2(amtp)]3+ (bpy = 2,2′-bipyridine, dpta = dipyrido-[3,2-a;2′,3′-c]-thien-[3,4-c]azine, amtp = 3-amino-1,2,4-triazino[5,6-f]-1,10-phenanthroline)
have been synthesized and characterized. The interaction of CoIII complexes with calf thymus DNA was investigated by spectroscopic and viscosity measurements. Results suggest that the two
complexes bind to DNA via an intercalative mode. Moreover, CoIII complexes have been found to promote the photocleavage of plasmid DNA pBR322 under irradiation at 365 nm. The mechanism studies
reveal that hydroxyl radical (OH•) is likely to be the reactive species responsible for the cleavage of plasmid DNA by [Co(bpy)2(dpta)]3+ and superoxide anion radical (O
2
•−
) acts as the key role in the cleavage reaction of plasmid DNA by [Co(bpy)2(amtp)]3+. 相似文献
11.
A. Ortiz S. Ramos-Bernal A. Negrón-Mendoza T. Martínez G. Sanchez-Mejorada 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(3):573-575
The thermoluminescense (TL) behavior of solid solutions of cadmium and manganese doped single crystals under γ-irradiation
is reported. Various compositions of single crystals of NaCl doped with Cd2+ and Mn2+ have been irradiated with ionizing radiation. The increase in the glow curve was followed as a function of the F-centers
produced by the dose. The analysis shows the potential use of these materials as dosimeters. 相似文献
12.
S. A. Bychkova A. V. Katrovtseva E. V. Kozlovskii 《Russian Journal of Coordination Chemistry》2008,34(2):93-96
The process of complex formation of maleic acid (H2L) with the ions Zn2+, Ni2+, Co2+, Cu2+ was studied by potentiometric titration in a wide range of concentration ratios at 298 K and I = 0.1 mol/l (NaNO3). The moieties ZnL, CoL, NiL, NiL 2 2? , CuL, and CuL 2 2? were detected and their stability constants were determined. 相似文献
13.
Claudia Iwashita Verinaud Gabriel Pinna Feliciano Roberta Rodrigues de Carvalho Alexandre Paulo Yague Lopes Isaías Raw Elizabeth Angélica Leme Martins Elisabeth Cheng 《Chromatographia》2017,80(9):1319-1327
Coagulation factor VIII (FVIII) is a glycoprotein that plays a crucial role in the clotting cascade. Replacement therapies with recombinant and plasma-derived concentrates of FVIII are used for treatment of hemophilia A. We have previously purified the human plasma FVIII by immobilized metal affinity chromatography (IMAC) using Cu2+ as the metal ligand. In this work we report the purification of FVIII using Zn2+ and Co2+, two metal ions that bind proteins more weakly. Human plasma was directly applied to the anion-exchange ANX Sepharose FF column and the eluate was used as starting material for the studies in IMAC columns. Using imidazole as desorbing agent, FVIII was recovered with 65% activity in the IMAC-Zn2+ column and with 74% activity in the IMAC-Co2+ column. Purification factors were 4 and 9, respectively. Using a pH gradient, FVIII was eluted at pH 5.0 with 17% activity in the IMAC-Zn2+ and 77% activity in the IMAC-Co2+. Vitamin K-dependent proteins, a family of proteins that includes Prothrombin and coagulation factor IX, coeluted with FVIII in the ANX Sepharose FF column and were recovered with the unbound proteins on both IMAC columns. Therefore, Co2+ and Zn2+ columns were as effective as the Cu2+ column in separating FVIII from vitamin K-dependent proteins. Finally, we have shown that FVIII remained complexed with the von Willebrand factor. 相似文献
14.
Xiaoju Liu Guoyu Ren Xiangrong Ma Yulin Xiang Liguo Gao Xiaoyan Ma 《Russian Journal of Applied Chemistry》2017,90(12):2016-2018
An efficient highly diluted synthetic approach to the synthesis of 1,9-dicarbonyl-2,8-dioxo-butyne ester ferrocenophane (L) has been developed. The title compound was characterized by IR, UV, FL, 1H NMR, spectroscopies, elemental analysis and so on. Further complex L shows fluorescence responses to Co2+ and Cu2+ in CH3OH, The results indicate that the complex could be applied in multianayte detection. The binding ability of receptor L CH3OH was tested for various cations (Co2+, Cu2+, Zn2+, and Ni2+ in water) and the binding constants for Co2+ and Cu2+ were the computed, having a distinct absorbance shift. The receptor is a very attractive array because its distinct absorbance shift profile in a semi-aqueous phase, making it applicable in the area of biology, environmental sciences and material chemistry. 相似文献
15.
CaAl2O4:Eu2+, Nd3+@TiO2 composite powders were synthesized by a sol–gel method under mild conditions (i.e. low temperature and ambient pressure).
The as-prepared powders were characterized by transmission electron microscopy (TEM) and analyzed by X-ray diffraction (XRD).
The photocatalytic behavior of the TiO2-base surfaces was evaluated by the degradation of nitrogen monoxide gas. It suggested that CaAl2O4:Eu2+, Nd3+@TiO2 composite powders were composed of anatase titania and that CaAl2O4:Eu2+, Nd3+. TiO2 particles were deposited on the surface of CaAl2O4:Eu2+, Nd3+ to form uniform film. CaAl2O4:Eu2+, Nd3+@TiO2 composite powders exhibited higher photocatalytic activity compared with pure TiO2 under visible light. And the result also clearly indicated that the long afterglow phosphor absorbed and stored lights for
the TiO2 to remain photocatalytic activity in the dark. 相似文献
16.
Lenoble V Garnier C Masion A Ziarelli F Garnier JM 《Analytical and bioanalytical chemistry》2008,390(2):749-757
This work allowed the characterization of the Cd-binding sites of two compounds taken as models for exudates, the main components
of soil organic matter (SOM). The studied compounds were exopolysaccharides (EPS), specifically exudates of roots (polygalacturonic
acid) and of soil bacteria (Phytagel). Potentiometric acid–base titrations were performed and fitting of the obtained results
indicated the presence of two main classes of acidic sites, defined by their pK
a values, for both EPS but of a different nature when comparing the two compounds. The two studied exopolysaccharides presented
different acidic/basic site ratios: 0.15 for Phytagel and 0.76 for polygalacturonic acid. Spectroscopic techniques (13C/113Cd NMR, FTIR) distinguished different Cd surroundings for each of the studied EPS, which is in agreement with the titration
results. Furthermore, these analyses indicated the presence of –COOH and –OH groups in various proportions for each exopolysaccharide,
which should be linked to their reactivity towards cadmium. Cadmium titrations (voltammetric measurements) also differentiated
different binding sites for each compound and allowed the determination of the strength of the Cd-binding site of the EPS.
Fitting of the results of such voltammetric measurements was performed using PROSECE (Programme d’Optimisation et de Speciation Chimique dans l’Environnement), a software coupling chemical speciation calculation and binding parameter optimization. The fitting, taking into account
the Cd2+/H+ competition towards exopolysaccharides, confirmed the acid-base titrations and spectroscopic analyses by revealing two classes
of binding sites: (i) one defined as a strong complexant regarding its Cd2+–EPS association (logK = 9–10.4) and with basic functionality regarding H+–EPS association (pK
a = 11.3–11.7), and (ii) one defined as a weak complexant (logK = 7.1–8.2) and with acidic functionality (pK
a = 3.7–4.0). Therefore the combination of spectroscopic analyses, voltammetry, and fitting allowed the precise characterization
of the binding sites of the studied exopolysaccharides, mimicking the main SOM components. Furthermore, the binding parameters
obtained by fitting can be used in biogeochemical models to better define the role of key SOM compounds like exudates of roots
and of soil bacteria on trace metal transport or assimilation. 相似文献
17.
A new perylene diimide (PDI) ligand (1) functionalized with a dipicolylethylenediamine (DPEN) moiety was synthesized and first
used as a colorimetric and fluorometric dual-channel sensor to specifically detect the presence of Cu2+ over a wide range of other cations. The solution of 1 (10 μmol/L) upon addition of Cu2+ displayed distinguishing pink color compared with other cations including K+, Ni2+, Ca2+, Mn2+, Na+, Sr2+, Zn2+, Co2+, Cd2+, Mg2+, Cr3+, Ag+, and Ba2+, indicating the sensitivity and selectivity of 1 to Cu2+. Thus, the advantage of this assay is that naked-eye detection of Cu2+ becomes possible. Moreover, among these metal ions investigated, only Cu2+ quenched more than half fluorescent intensity of 1. The ESI-TOF spectrum of a mixture of 1 and CuCl2 in combination of the fluorescence titration spectra of 1 (10 μmol/L) upon addition of various amounts of Cu2+ revealed the formation of a 2:1 metal-ligand complex through the metal coordination interaction.
Supported by the National Natural Science Foundation of China (Grant Nos. 20872101 & 20772086) 相似文献
18.
H. M. Ye N. Ren H. Li J. J. Zhang S. J. Sun L. Tian 《Journal of Thermal Analysis and Calorimetry》2010,101(1):205-211
The complex of [Nd(BA)3bipy]2 (BA = benzoic acid; bipy = 2,2′-bipyridine) has been synthesized and characterized by elemental analysis, IR spectra, single
crystal X-ray diffraction, and TG/DTG techniques. The crystal is monoclinic with space group P2(1)/n. The two–eight coordinated Nd3+ ions are linked together by four bridged BA ligands and each Nd3+ ion is further bonded to one chelated bidentate BA ligand and one 2,2′-bipyridine molecule. The thermal decomposition process
of the title complex was discussed by TG/DTG and IR techniques. The non-isothermal kinetics was investigated by using double
equal-double step method. The kinetic equation for the first stage can be expressed as dα/dt = A exp(−E/RT)(1 − α). The thermodynamic parameters (ΔH
≠, ΔG
≠, and ΔS
≠) and kinetic parameters (activation energy E and pre-exponential factor A) were also calculated. 相似文献
19.
Soraia Meghdadi Mehdi Amirnasr Mohammad H. Habibi Ahmad Amiri Fatemeh Ahmadi Keiko Kihara Takayoshi Suzuki Hamid Reza Bijanzadeh 《Transition Metal Chemistry》2008,33(7):879-886
The structure, spectroscopic, and electrochemical properties of [Co{(BA)2pn}(L)2]ClO4 complexes, where (BA)2pn = N,N′-bis(benzoylacetone)-1,3-propylenediimine dianion and the two ancillary ligands (L) are pyridine, py (1), and 4-methylpyridine, 4-Mepy (2), have been investigated. These complexes have been characterized by elemental analyses, IR, UV–Vis and 1H-NMR spectroscopy. The crystal structure of [Co{(BA)2pn}(py)2]ClO4 (1) has been determined by X-ray diffraction. The coordination geometry around cobalt(III) is best described as a distorted
octahedron. The electrochemical reduction of these complexes at a glassy carbon electrode in acetonitrile solution indicates
that the first reduction process corresponding to CoIII–CoII is electrochemically irreversible, which is accompanied by the dissociation of the axial N(py)–cobalt bonds. This process
becomes quasi-reversible upon the addition of excess py ligands. The second reduction step of CoII/I shows reversible behavior and is not influenced by the nature of the axial ligands.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
20.
The photoluminescence properties of xZnO–(100−x)SiO2 (x = 0, 5, 10, 20) containing 1% Eu2O3 prepared by a sol–gel method were systematically investigated. The results indicated that the relative proportion of f–f transitions to charge transfer (CT) absorption decreased with the increase of ZnO concentration. The intensity of 5D0–7FJ transitions of Eu3+ ions was enhanced with the increase of ZnO content due to local structure changes and decreased quantities of Eu3+ ions clusters. The results of fluorescence line narrow (FLN) spectra indicated that Eu3+ ions occupied one site in SiO2 glass and two sites in ZnO–SiO2 glasses. The second-order crystal field parameters were calculated. B20 and B22 for site 1 increased with excitation energy, while ones hardly changed for site 2. 相似文献