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1.
《Journal of Dispersion Science and Technology》2013,34(2-3):197-202
Cu(II)-salicylate was synthesized and characterized by X-ray diffraction. The reaction mechanism of the Cu(II) complex with superoxide anion was studied by ESR spectroscopy, and its (superoxide dismutase) SOD-like activity was determined by a modified illumination method in phosphate buffer (pH = 7.8), micelle solutions and lamellar liquid crystals formed from surfactants CTAB and TX-100. X-ray diffraction indicated that the Cu(II) complex had a formula Cu2(Hsal)4EtOHH2O and a similar structure to the SOD active site. EPR spectra proved that the reaction mechanism of the Cu(II) complex catalyzing O 2 .- dismutation was the same as that of the proposed dismutation reaction catalyzed by SOD. Results obtained by the NBT method indicated that the Cu(II)-complex showed SOD-like activity, and the effect of microenvironment created by surfactants on its activity was same as on SOD activity. The order of the inhibition of NBT reduction by the Cu(II)-complex in different microenvironments was: in phosphate buffer (pH = 7.8) > in TX-100 micelle > in TX-100 liquid crystal, and in nonionic TX-100 organized assemblies > in cationic CTAB organized assemblies. These results were explained by the catalytic effect of micelles, and by the space restriction and high viscosity of organized assemblies of surfactants. 相似文献
2.
S. M. Dal Bosco R. S. Jimenez C. Vignado J. Fontana B. Geraldo F. C. A. Figueiredo D. Mandelli W. A. Carvalho 《Adsorption》2006,12(2):133-146
The adsorption capacities of commercial and Brazilian natural clays were evaluated to test their applications in wastewater
control. We investigated the process of sorption of manganese(II) and cadmium(II) present in synthetic aqueous effluents,
by calculating the adsorption isotherms at 298 K using batch experiments. The influence of temperature and pH on the adsorption
process was also studied. Adsorption of metals was best described by a Langmuir isotherm, with values of Q
0 parameter, which is related to the sorption capacity, corresponding to 6.3 mg g− 1 for K-10/Cd(II), 4.8 mg g− 1 for K-10/Mn(II), 11.2 mg g− 1 for NT-25/Cd(II) and 6.0 mg g− 1 for NT-25/Mn(II). We observed two distinct adsorption mechanisms that may influence adsorption. At the first 5 min of interaction,
a cation exchange mechanism that takes place at exchange sites located on (001) basal planes is predominant. This process
is inhibited by low pH values. After this first and fast step, a second sorption mechanism can be related to formation of
inner-sphere surface complexes, which is formed at edges of the clay. The rate constants and the initial sorption rates correlate
positively with temperature in all studied systems, denoting the predominance of a physisorption process. The addition of
complexing agents that are incorporated within the K10 structure, enhance metal uptake by the adsorbent. The results have
shown that both Cd(II) and Mn(II) were totally retained from a 50 mg L− 1 solution when K10 grafted with ammonium pyrrolidinedithiocarbamate (APDC) was used as adsorbent. 相似文献
3.
The effects of a substrate additive, H+ and solvents (water and acetone), on the micelle-catalyzed aquation of tris-(4,7-diphenyl-1, 10-phenanthroline)iron(II),
Fe(Ph2Phen)3
2+, have been investigated using#Triton X-100 micelles. The k0
vs. [TX-100] profiles at fixed [H2O] are structured, exhibiting maxima. Catalytic factors of 46.6–171.7 are observed for 5.56×10−2≤[H2O] 55.60×10−2 mol dm−3. On the other hand, at fixed [H+], the k0
vs. [TX-100] exhibit broad maxima. The aquation reaction is inhibited by H+ and catalytic factors decrease rapidly and exponentially from 422.5 to 20.9 for 0.20×10−3≤[H+]≤2.00×10−3 mol dm−3. The aquation is found to be faster (ca. 160–1200 fold) in acetone than in the aqueous medium depending on the added [H2O]. These observations are rationalized on the basis of a proposed modified lamellar structure for the Triton X-100 (TX-100)
micelles in which direct substitution of water molecules into the coordination sphere of the complex occurs. 相似文献
4.
A new simple and inexpensive optical chemical sensor for cadmium(II) ions is presented. The cadmium sensing system was prepared
by incorporating 2-amino-cyclopentene-1-dithiocarboxylic acid (ACDA) on a triacetylcellulose membrane. The absorption spectra of the optical sensor membrane in Cd(II) solution showed a maximum
peak at 430 nm. The proportionality in intensity of the membrane color on the optode to varying amounts of Cd(II) suggests
its potential applications for screening Cd(II) in aqueous samples by visual colorimetry. The sensor provided a wide concentration
range of 3.0 × 10−6–3.4 × 10−4 M of Cd(II) ions with a detection limit of 1.0 × 10−6 M (0.2 μg/mL). The relative standard deviations for eight replicate measurements of 8.0 × 10−6 and 5.0 × 10−5 M Cd(II) were 2.7 and 2.3%, respectively. The response time of the optode was 6 min. The influence of interfering ions on
the determination of 1.0 × 10−5 M Cd(II) was studied and the main interferences were removed by extraction method. The sensor was applied to the determination
of Cd(II) in water samples. 相似文献
5.
Ashok Kumar Singh Ravindra Pratap Singh Sameena Mehtab 《Journal of inclusion phenomena and macrocyclic chemistry》2008,60(1-2):9-15
A new polystyrene based membrane electrode of methyl substituted 6,7:13,14-dibenzo-2,4,9,11-tetraphenyl-1,5,8,12-tetraazacyclotetradeca-1,4,6,8,11,13-hexaene
(I) with sodium tetraphenylborate (NaTPB) and dibutyl phthalate (DBP) as anion excluder and plasticizing agent was prepared and
investigated as Hg (II)-selective electrode. The electrode exhibits a Nernstian response for Hg (II) ions over a wide concentration
range of 1.0 × 10−1–8.9 × 10−6 M with a slope of 30 ± 1 mV per decade concentration. It has a response time of 10 s and can be used for at least 4 months
without any divergence in potentials. The membrane works satisfactorily in a partially non-aqueous medium up to a maximum
30% (v/v) content of methanol and ethanol. The proposed sensor revealed good selectivity over a wide variety of other cations
including alkali, alkaline earth, heavy and transition metal ions and could be used in a pH range of 2.5–5.0. Normal interferents
like Ag+, Cd2+ and Pb2+ low interfere in the working of the electrode. The electrode was successfully used in the direct determination of Hg2+ in aqueous solution. 相似文献
6.
Carlos E. C. Magalhães Éder C. Lima Francisco J. Krug Marco A. Z. Arruda 《Mikrochimica acta》1999,132(1):95-100
A method for direct analysis of tea and coffee samples by using electrothermal atomic absorption spectrometry is described.
Coffee and tea from different sources were analyzed without digestion step. For slurry analyses the samples were ground, sieved
at 105 μm and then suspended in 0.2% v/v HNO3 and 10% v/v Triton X-100 medium. For liquid phase aluminium determination the samples were prepared in the same way and only
the liquid is introduced directly into the graphite furnace. Calibration was performed by aqueous standards for both cases
and the determinations were carried out in the linear range between 50 and 250 μg L−1. The characteristic mass of aluminium and the detection limit were 45 pg and 2 μg L−1, respectively. Using a typical 0.1% m/v coffee slurry sample, the relative standard deviation of measurements (n=15) for
repeatability was about 8.2%.
Received December 27, 1998. Revision March 18, 1999. 相似文献
7.
A flow injection method is described for the determination of iron in fresh water based on potassium permanganate chemiluminescence
detection via oxidation of formaldehyde in aqueous hydrochloric acid. Total iron concentrations are determined after reducing
Fe(III) to Fe(II) using hydroxylamine hydrochloride. The detection limit (three standard deviations of blank) is 1.0 nM, with
a sample throughput of 120 h−1. The calibration graph was linear over the range (2–10) × 10−7 M (r
2 = 0.9985) with relative standard deviations (n = 5) in the range 1.0–2.3%. The effect of interfering cations (Ca(II), Mg(II), Zn(II), Ni(II), Co(II), Fe(III), Mn(II), Pb(II),
and Cu(II)) and common anions (Cl−, SO
4
2−
, PO
4
3−
, NO
3
−
, NO
2
−
, I−, F−, and SO
3
2−
) was studied at their maximum admissible concentrations in fresh water. The method was applied to fresh-water samples from
the Quetta Valley, and the results obtained (0.04 ± 0.001–0.11 ± 0.01 mg/L Fe(II)) were in reasonable agreement with those
obtained using the spectrophotometric reference method (0.05 ± 0.01–0.12 ± 0.02 mg/L Fe(II)).
The text was submitted by the authors in English. 相似文献
8.
The polyoxyethylene chain of non-ionic surfactant Triton X-100 [4-(1,1,3,3-tetramethylbutyl) phenyl polyethylene glycol,TX-100] was degraded by permanganate in the presence of HClO4. The oxidative degradation rate and cloud point have been obtained as a function of [surfactant], [permanganate], [HClO4], and temperature. Dependence of the reaction rate on adding inorganic salts (Na4P2O7, NaF and MnCl2) was also examined. The oxidation rate increased with increase in [TX-100] and [H+]. The higher order kinetics with respect to [TX-100] at lower [H+] shifted to lower order at higher [H+]. The cloud point of TX-100 (67°C) shifted to lower temperature (23±0.5°C) after oxidative degradation of the polyoxyethylene chain. Evidence of complex formation between TX-100 and MnO
4
−
was obtained spectrophotometrically. Presence of the primary alcoholic (–OH) group in the TX-100 skeleton is responsible for the degradation of oxyethylene chain. Both monomeric and aggregated TX-100 molecules are oxidized by permanganate. A catalytic oxidation mechanism is proposed on the basis of the experimental findings. 相似文献
9.
The main purpose of this study is to develop an inexpensive, simple, selective and especially sensitive modified carbon paste
electrode (MCPE) for the determination of dopamine (DA) in pharmaceutical and human serum samples. The carbon paste electrode (CPE) has been modified by using [N,N′-bis(2-pyridine carboxamido)-1,2-benzene] nickel(II) complex (Ni(II)bpb) and the electrochemical
behavior of the modified electrode has been studied by cyclic voltammetry. The modified electrode shows an excellent electrocatalytic
effect on the oxidation of DA. Under optimum conditions, calibration plots are found to be linear in the range of 7.0 × 10−7−1.0 × 10−5 M (r
2 = 0.9940) and 1.0 × 10−5−1.0 × 10−4 M (r2 = 0.9945); the detection limit is 6.2 × 10−8 M. The preparation of MCPE is very easy. The electrode can be renewed by simple polishing. The proposed method shows good
sensitivity, reproducibility (RSD ∼ 2.9%), high stability (more than two month) without any considerable change in response
and recovery for the determination of DA. The prepared electrode has been successfully applied to the voltammetric determination
of DA in pharmaceutical and biological samples.
The article is published in the original. 相似文献
10.
Abstract Interaction between dye (ECAB), nonionic surfactant (TX-100) micelle in aqueous solution and TX-100 hemimicelie at solid (SiO2)/liquid interface has been investigated quantitatively. There are linear relationships between concentrations of free ECAB(Ca), ECAB bound with TX-100 micelles in solution(Cm) and ECAB bound with TX-100 hemimicelles at interface of solid/liquid(Chm). The slopes of the three straight lines are 0.32 for Chm~Ca -1.32 for Cm~Ca and -1.00 for (Cm+Chm~Ca respectively. The linear relationships can be described by three linear equations as follows: Chm=0.32 (Ca?O.88×10?5),Cm.=4.0×10?5-l.33 Ca and Chm+Cm=3.742×l0?5-Ca,. It is inferred that the interaction between ECAB, TX-100 micelles and TX-100 hemimicelles is essentially partition of ECAB molecules in solution, TX-100 micelles and hemimicelles. The concentration of ECAB bound with TX-100 micelles well as electronic repulsion. Additionally, A quantitative method to determine adsorbance of surfactant TX-100 on silica gel by spectroscopy in coadsorption conditions of dye (ECAB) and TX-100 was proposed. 相似文献
11.
Heterocyclic thiocarboxylic acids have been designed to prepare polymeric membrane ion-selective electrode (ISE) for Pb2+. Construction, response characteristic and application of the lead ISEs are investigated. Better results have been obtained
with membranes containing ligands L1∼L3 with bis(2-ethylhexyl) sebacate (DOS) as a plasticizer. Ionophores L1∼L3 are [(4,6-dimethyl-2-pyrimidinyl) thio] acetic acid (L1), (1,3,4-thiadiazole-2,5-diyldithio) diacetic acid (L2) and (1,3,4-thiadiazole-2,5-diyldithio) dipropionic acid (L3). The optimum electrodes have the composition of L1 (1.6): PVC (32.7): DOS (65.3): KT
p
ClPB (0.4) (w/w), L2 (1.0): PVC (32.8): DOS (66.0): KT
p
ClPB (0.2) (w/w), and L3 (1.0): PVC (32.7): DOS (65.4): KT
p
ClPB (0.9) (w/w). The optimized membrane electrodes work well over a wide range of concentrations (1.0 × 10−5 ∼1.0 × 10−2 M, 1.0 × 10−6 ∼1.0 × 10−2 M, and 1.0 × 10−6 ∼1.0 × 10−2 M) with the response slope of 27.4, 30.1 and 29.2 mV/decade, respectively. Potentiometric selectivities of the ISEs based
on L1 ∼ L3 for Pb2+ over other interfering ions are determined with the fix interference method. The electrodes display good selectivity over
a number of alkali, alkaline earth, transition and heavy metal ions. The lifetime of the electrodes is about 2 months and
their response time is 20 s. Applications of these electrodes for the determination of lead in real samples and as indicator
electrodes for potentiometric titration of Na2SO4 using Pb2+ solution are reported. 相似文献
12.
《Analytical letters》2012,45(8):1455-1464
Abstract Some new PVC membrane electrodes based on Co(II), Mn(II), Ni(II), Cu(II), and Zn(II)chelates of bis-furfural-semi-o-tolidine as carriers are described. The electrodes exhibited different selectivity behaviour compared with the electrode using a classical anion exchanger such as tetraalkyl ammonium. The results showed that the Cobalt(II) chelate-based electrodes had a Nernstian response to iodide ion ranging from 1.0 × 10?1 to 1.0 × 10?6 mol.L?1 in a phosphate buffer solution of pH 2.0 with a detection limit of 6.4 × 10?7 mol.L?1 and a slope of 57.8 mV/dec at 25deg;C. The response mechanism was also investigated by use of both a.c. impedance and SPQC techniques. The Co(II) chelate-based electrodes were used to determine the iodide content of a drug with satisfactory results. 相似文献
13.
A. V. Pardhi A. D. Bansod A. R. Yaul A. S. Aswar 《Russian Journal of Coordination Chemistry》2010,36(4):298-304
Coordination polymers of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) with the salen-type Schiff base 4,4′-bis[(N-ethanesalicylaldehydediamine-5)azo]biphenyl
have been prepared and characterized by elemental analyses, IR and electronic spectra, magnetic susceptibility measurements,
and thermogravimetric analysis. Thermogravimetric analysis confirms the coordination of H2O in complexes. The 1H NMR spectrum of ligand clearly indicates the presence of OH and azomethine groups. The octahedral geometry have been suggested
for Mn(II), Fe(II), Co(II), and Ni(II) complexes, and square planar Cu((II), whereas tetrahedral is suggested for Zn(II) and
Cd(II) polychelates. Thermal data have been analyzed for kinetic parameters by both Coat-Redfern and Broido methods. Solid-state
dc conductivity of ligand and its polychelates was measured in their compressed pellet form over 313–413 K temperature range.
Solidstate conductivity lies in the range 4.361 × 10−11 to 7.241 × 10−10 Ohm−1 cm−1 indicating their semiconducting behavior. Oxidation of styrene with selected catalysts was tested using H2O2 as an oxidant. 相似文献
14.
N. Furusawa 《Chromatographia》1999,49(7-8):369-373
Summary A rapid method for the simultaneous determination/identification of residual oxytetracycline (OTC) and sulphadimidine (SDD)
in meats (beef, pork, chicken) and eggs by high-performance liquid chromatography (HPLC) was developed. The extraction of
OTC and SDD was performed using a Sep-Pak? CN cartridge. The extracts contained OTC/SDD analytes when examined by HPLC using a LiChrospher? 100 RP-8 end-capped column and a mobile phase of acetonitrile-acetic acid-water (28:4:68, v/v/v) with a photodiode array
detector. The average recoveries from spiked samples (0.1 μg g−1 and 1.0 μg g−1) were in excess of 80.2% with coefficients of variation between 1.5 and 5.0%. The limits of detection for OTC and SDD were
0.05 and 0.02 μg g−1, respectively. 相似文献
15.
Shuangming Meng Buqin Jing Yueqin Fan Yongwen Liu Yong Guo 《Journal of Analytical Chemistry》2011,66(1):31-36
A new highly sensitive and selective chromogenic reagent, 3,5-bis(4-phenylazophenylaminodiazo)benzoic acid (BPPABA) has been synthesized and applied to the determination of trace cadmium(II) in vegetables. The method is based on the color
reaction between BPPABA and cadmium (II). In the presence of Triton X-100, cadmium(II) reacts with BPPABA in Na2B4O7-NaOH buffer solution (pH 10.5), forming red complex with maximum absorption at 530 nm. Under the optimal conditions, Beer’s
law is obeyed within 0–12 μg of cadmium within 25 mL of solution, and the apparent molar absorptive coefficient of the complex
is 2.8 × 105 L/mol cm. The detection limit and the relative standard deviation were found to be 0.92 μg/L and 1.0%, respectively. Interference
of foreign ions was also investigated. Most of the metal ions are tolerated in considerable amounts except for Hg(II), Cu(II)
and Ni(II). To eliminate the interference of foreign ions, metal ion imprinted polymer technique was utilized. 相似文献
16.
Dong-Yu Lv Zhu-Qing Gao Jin-Zhong Gu Jian-Zhao Liu Wei Dou 《Transition Metal Chemistry》2011,36(3):275-281
Two Mn(II) coordination polymers, namely [Mn(bpda)]
n
(1) and [Mn(bpda)(bpy)0.5]
n
(2) (H2bpda = 1,1′-biphenyl-3,3′-dicarboxylic acid and bpy = 4,4′-bipyridine), have been synthesized from H2bpdc, bpy, and MnSO4·2H2O under hydrothermal conditions. The complexes were characterized by physicochemical and spectroscopic methods, as well as
by X-ray crystallography. Compound 1 possesses a 3D structure consisting of carboxylate-bridged edge-sharing Mn–O–Mn double chains. Compound 2 features a 3D open structure with a dinuclear Mn(II) secondary building unit. Magnetic susceptibility measurements of compounds
1 and 2 exhibit antiferromagnetic interactions between the nearest Mn(II), with J = –11.3 cm−1 and g = 2.12 for 1, and J = –13.5 cm−1 and g = 2.12 for 2. 相似文献
17.
Pradip Kumar Ghosh Harasit Kumar Mandal Ambikesh Mahapatra 《Transition Metal Chemistry》2010,35(6):679-687
Interaction of adenine (A) with dichloro-[1-alkyl-2-(α-naphthylazo)imidazole] palladium(II) [Pd(α-NaiR)Cl2], 1 and dichloro-[1-alkyl-2-(β-naphthylazo)imidazole] palladium(II) [Pd(β-NaiR)Cl2], 2 {where R=Me (a), Et (b) or Bz (c)} in MeCN-water (50% v/v) medium to yield [{1-alkyl-2-(α-naphthylazo)imidazole}(adenine)]palladium(II) perchlorates (3a, 3b, 3c) and [{1-alkyl-2-(β-naphthylazo)imidazole}(adenine)]palladium(II) perchlorates (4a, 4b, 4c) was studied. The products were characterized by physico-chemical and spectroscopic methods. The reaction kinetics were second
order overall, being first order in both the Pd(II) complex and adenine. The effect of adding chloride was consistent with
rate-limiting dissociation of chloride from the complex. Thermodynamic parameters were determined from temperature variation
experiments. The second-order rate constant k
2
corroborates with the experimental Δ‡H° values, while the negative values of Δ‡S° indicate that the reaction proceeds through an associative inner sphere mechanism. 相似文献
18.
K. M. El-Azony M. Ismail Aydia A. A. El-Mohty 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):381-388
Triton X-100 cerium(IV) phosphate (TX-100CeP) was synthesized and characterized by using IR, X-ray, TGA/DT and the elemental
analysis. The chemical stability of TX-100CeP versus the different concentrations of HCl acid was studied before and after
its exposure to the radiation dose (30 K Gray). The effect of HCl concentration on separation of Cr(III) from Cr(VI) by using
TX-100CeP as surface active ion exchanger was also studied. A novel method was achieved for the quantifying of Cr(III) and
Cr(VI) ions by using the high-performance liquid chromatography (HPLC) at wavelength 650 nm, a stationary phase consists of
reversed phase column (Nucleosil phenyl column; 250 × 4.6 mm, 5 μm), and a mobile phase consists of 0.001 M di-(2-ethylhexyl)
phosphoric acid (DEHPA) in methanol:water (70:30 v/v). The retention times were 7.0 and 8.5 min, for the Cr(III) and Cr(VI),
respectively. The exchange capacity of Cr(III) was quantified (2.1 meq/g) onto the TX-100CeP. 相似文献
19.
Sh. Dehghan Abkenar Z. Dahaghin H. Bagheri Sadeghi M. Hosseini M. Salavati-Niasari 《Journal of Analytical Chemistry》2011,66(6):612-617
In this study, a new and simple homogeneous liquid-liquid extraction (HLLE) method based on a pH-independent phase-separation process was developed using a ternary solvent system [water-tetrabutylammonium
ion (TBA
+)-chloroform] for the preconcentration of Zn2+ ions. A Schiff’s base ligand was used as the chelating agent prior to Zn2+ ions extraction. Flame atomic absorption spectrophotometry using acetylene-air flame was used for the quantification of analyte
after preconcentration. The phase separation occurred due to ion-pair formation of TBA and perchlorate ion. The sedimented
phase was then separated using a 100 μL micro-syringe and diluted to 1.0 mL with ethanol. The sample was introduced into the
flame by conventional aspiration. After the optimization of complexation and extraction conditions such as pH 9.0, [ligand]
= 1.0 × 10−5 M, [TBA+] = 2.0 × 10−2 M, 100.0 μL of [CHCl3] and [CLO4−] = 2.0 × 10−2 M, a preconcentration factor of 100 was achieved for only 10 mL of the sample. The relative standard deviation was 2.3% (n = 10). The limit of detection was sufficiently low and at ppb level. The proposed method was applied to the extraction and
determination of Zn2+ in natural water samples with satisfactory results. 相似文献
20.
A new poly(vinyl chloride)-based membrane was fabricated with the cobalt(II) complex of 2,4-dimethyl-1,5,8,11-tetraazacyclotrideca-1,4-diene
[Me2(13)dieneN4] as an ion carrier. The membrane composition was Co2+ complex/PVC/NaTPB/DBP 15:50:15:20 (w/w). The sensor exhibited a Nernstian response for Co2+ ions over a wide concentration range (7.94×10−6–1.0×10−1 M) at pH 2.5–7.0, a response time of 10 s, and it could be used for 3 months without any significant divergence in potential.
The proposed membrane sensor exhibited good selectivity for Co2+ over a wide variety of other metal ions and in mixtures containing up to 25% (v/v) non-aqueous content. The sensor was successfully
used as an indicator electrode in the potentiometric titration of Co2+ with EDTA and the direct determination of Co2+ in real samples. 相似文献