首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
ABSTRACT

In this study, preconcentration and separation of Cu(II) and Pb(II) ions by using Fe3O4@SiO2@Bacillus pumilis before their determinations by flame atomic absorption spectrometry (FAAS) were investigated. The thermophilic Bacillus pumilis were isolated from Meyremderesi spring, ??rnak, Turkey. Effects of important parameters such as pH, adsorbent amount, eluent type, concentration and volume of eluent and sample volume on magnetic solid phase extraction (MSPE) were examined in details. The preconcentration factors for Cu(II) and Pb(II) ions were calculated as 30 and 40, respectively. The accuracy of the proposed extraction procedure was validated analysing certificated reference materials and addition – recovery tests. The concentration of copper and lead were determined in water samples from Turkey by Flame AAS after application developed preconcentration-separation method.  相似文献   

2.
Isotope dilution is a useful technique to measure the labile metal pool, which is the amount of metal in soil in rapid equilibrium (<7 days) with the soil solution. This is normally performed by equilibrating soil with a metal isotope, and sampling the labile metal pool by using an extraction (E value), or by growing plants (L value). For Cu, this procedure is problematic for E values, and impossible for L values, due to the short half-life of the 64Cu radioisotope (12.4 h), which makes access and handling very difficult. We therefore developed a technique using enriched 65Cu stable isotope and measurement of 63Cu/65Cu ratios by quadrupole inductively coupled plasma mass spectrometry (ICP-MS) to measure labile pools of Cu in soils using E value techniques. Mass spectral interferences in detection of 63Cu/65Cu ratios in soil extracts were found to be minimal. Isotope ratios determined by quadrupole ICP-MS compared well to those determined by high-resolution (magnetic sector) ICP-MS. E values determined using the stable isotope technique compared well to those determined using the radioisotope for both uncontaminated and Cu-contaminated soils.  相似文献   

3.
Total dissolved and labile concentrations of Cd(II), Cu(II), Ni(II) and Pb(II) were determined at six locations of the Bourgas Gulf of the Bulgarian Black Sea coast. Solid phase extraction procedure based on monodisperse, submicrometer silica spheres modified with 3-aminopropyltrimethoxysilane followed by the electrothermal atomic absorption spectrometry (ETAAS) was developed and applied to quantify the total dissolved metal concentrations in sea water. Quantitative sorption of Cd, Cu, Ni and Pb was achieved in the pH range 7.5–8, for 30?min, adsorbed elements were easily eluted with 2?mL 2?mol?L?1 HNO3. Since the optimal pH for quantitative sorption coincides with typical pH of Black Sea water (7.9–8.2), on-site pre-concentration of the analytes without any additional treatment was possible. Detection limits achieved for total dissolved metal quantification were: Cd 0.002?µg?L?1, Cu 0.005?µg?L?1, Ni 0.03?µg?L?1, Pb 0.02?µg?L?1 and relative standard deviations varied from 5–13% for all studied elements (for typical Cd, Cu, Ni and Pb concentrations in Black Sea water). Open pore diffusive gradients in thin films (DGT) technique was employed for in-situ sampling and pre-concentration of the sea water and in combination with ETAAS was used to determine the proportion of dynamic (mobile and kinetically labile) species of Cd(II), Cu(II), Ni(II) and Pb(II) in the sea water. Obtained results showed strong complexation for Cu and Pb with sea water dissolved organic matter. The ratios between DGT-labile and total dissolved concentrations found for Cu(II) and Pb(II) were in the range 0.2–0.4. For Cd and Ni, these ratios varied from 0.6 to 0.8, suggesting higher degree of free and kinetically labile species of these metals in sea water.  相似文献   

4.

The molecular structure of N,N′-o-phenylene-bis(salicylideneaminato)copper(II) (Cu(saloph)) was determined using the combination of gas-phase electron diffraction (GED), mass spectrometry, and quantum-chemical calculations. According to both experimental and theoretical approaches the molecule of Cu(saloph) is planar and possesses C 2v symmetry. Main structural parameters determined by GED experiment are the following (total error is given in a brackets): r h1(Cu–N) = 1.960(20) Å, r h1(Cu–O) = 1.913(17) Å, ∠NCuN = 82.7(18)°, ∠OCuO = 91.6(21)°, ∠NCuO = 92.9(9)°. The experimental structural parameters of Cu(saloph) molecules determined by X-ray single crystal analysis and GED experiments were discussed and compared to the theoretical ones.

  相似文献   

5.
A novel silica sorbent, silica gel-immobilized 5-aminoisophthalohydrazide (SiO2-APH), was prepared by the condensation of 3-chloropropyl-functionalized silica gel with 5-aminoisophthalohydrazide (APH) derived from dimethyl 5-aminoisophthalate as a starting material and used for separation and preconcentration of Cu, Zn, and Pb metals in water samples using Flame Atomic Absorption Spectrometry (FAAS). The characterization of the new sorbent was carried out by Elemental Analysis, Thermogravimetric Analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). Important analytical parameters including as pH, amount of sorbent, type and amount of eluting solvent, sample volume, vortex and ultrasonic bath time, matrix ions that effect the developed SiO2-APH-solid phase extraction (SPE) method were investigated and optimum parameters were detected. Recoveries of examined metals were obtained as 98% for Cu and Pb and 101% for Zn. The relative standard deviation (RSD, n = 8) of Cu, Zn and Pb metals were 3.2, 2.8 and 1.6%, respectively. Limit of detections (LODs) (n = 10) were found as 2.7 μg L−1 for Cu, 7.4 μg L−1 for Zn and 3.5 μg L−1 for Pb μg L−1. The accuracy of the new method was assessed by analyzing of TMDA-51.4 and TMDA-70.2 certified reference materials. The results obtained for metals were in a good agreement with certified values. Addition/recovery test was applied to the real well, river, dam and stream water samples to check the accuracy of the method. The results showed that the developed SiO2-APH-SPE method can be effectively used as an alternative method for determination of Cu, Zn, and Pb metals in water samples.  相似文献   

6.
The ionization constant of p-(2-hydroxy-1-naphthylazo)benzene-sulphonate (Orange II) and the formation constants of the metal chelates of this reagent with Ni(II) and Cu(II) have been determined spectrophotometrically in aqueous solution at 25° and at an ionic strength of 0.10M. The ionization constant of orange II was found to be pKa=10.95. Formation of orange II chelates with Ni(II) and Cu(II) was pH dependent, and the optimum pH range of the Ni(II) Chelate was at pH 9.2-9.4, and Cu(II) chelate at 9.5-9.7, respectively. The mole ratio of orange II to both of metal ions was found to be 2 to 1 stoichiometry. The formation constants (logK) of the Ni(II) and Cu(II) chelates were 12.50 and 16.11, respectively. The molar extinction coefficients and the photometric sensitivities of these chelates were determined.  相似文献   

7.
A novel HPLC method is described for separation of the three stereoisomers of octahydroindole-2-carboxylic acid (Oic), an intermediate in the synthesis of perindopril. The chiral mobile phase contained the complex of Cu(II) with the optically active selector L-phenylalaninamide (L-PheA), and an ion-pair reagent, sodium 1-octanesulfonate. The effects of the concentrations of the Cu(II)–L-PheA complex and the ion-pair reagent, mobile phase pH, ionic strength, acetonitrile content, and column temperature were studied. Satisfactory resolution was achieved for three stereoisomers, RRR-, SSS-, and SRR-Oic.  相似文献   

8.
We report the synthesis, crystal structures, thermal and magnetic characterizations of a family of metal‐organic frameworks adopting the niccolite (NiAs) structure, [dmenH22+][M2(HCOO)62−] (dmen=N,N′‐dimethylethylenediamine; M=divalent Mn, 1Mn ; Fe, 2Fe ; Co, 3Co ; Ni, 4Ni ; Cu, 5Cu ; and Zn, 6Zn ). The compounds could be synthesized by either a diffusion method or directly mixing reactants in methanol or methanol–water mixed solvents. The five members, 1Mn , 2Fe , 3Co , 4Ni , and 6Zn are isostructural and crystallize in the trigonal space group P 1c, while 5Cu crystallizes in C2/c. In the structures, the octahedrally coordinated metal ions are connected by anti–anti formate bridges, thus forming the anionic NiAs‐type frameworks of [M2(HCOO)62−], with dmenH22+ located in the cavities of the frameworks. Owing to the Jahn–Teller effect of the Cu2+ ion, the 3D framework of 5Cu consists of zigzag Cu‐formate chains with Cu OCHO Cu connections through short basal Cu O bonds, further linked by the long axial Cu O bonds. 6Zn exhibits a phase transition probably as a result of the order–disorder transition of the dmenH22+ cation around 300 K, confirmed by differential scanning calorimetry and single crystal X‐ray diffraction patterns under different temperatures. Magnetic investigation reveals that the four magnetic members, 1Mn , 2Fe , 3Co , and 4Ni , display spin‐canted antiferromagnetism, with a Néel temperature of 8.6 K, 19.8 K, 16.4 K, and 33.7 K, respectively. The Mn, Fe, and Ni members show spin‐flop transitions below 50 kOe. 2Fe possesses a large hysteresis loop with a large coercive field of 10.8 kOe. The Cu member, 5Cu , shows overall antiferromagnetism (both inter‐ and intra‐chains) with low‐dimensional characteristics.  相似文献   

9.
D‐glucosamine Schiff base N‐(2‐deoxy‐β‐D‐glucopyranosyl‐2‐salicylaldimino) and its Cu(II) and Zn(II) complexes were synthesized and characterized. The hydrolysis of p‐nitrophenyl picolinate (PNPP) catalyzed by ligand and complexes was investigated kinetically by observing the rates of the release of p‐nitrophenol in the aqueous buffers at 25°C and different pHs. The scheme for reaction acting mode involving a ternary complex composed of ligand, metal ion, and substrate was established and the reaction mechanisms were discussed by metal–hydroxyl and Lewis acid mechanisms. The experimental results indicated that the complexes, especially the Cu(II) complex, efficiently catalyzed the hydrolysis of PNPP. The catalytic reactivity of the Zn(II) complex was much smaller than the Cu(II) complex. The rate constant kN showing the catalytic reactivity of the Cu(II) complex was determined to be 0.299 s?1 (at pH 8.02) in the buffer. The pKa of hydroxyl group of the ternary complex was determined to be 7.86 for the Cu(II) complex. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 345–350, 2002  相似文献   

10.
4-Morpholinoacetophenone thiosemicarbazone, MAPT, and its nickel(Ⅱ) and copper(Ⅱ) complexes have been prepared and characterized by elemental analysis, magnetic susceptibility, spectral methods (FT-IR, ^1H NMR) and cyclic voltammetry. Electrochemical behaviors of the complexes have been studied by cyclic voltammetry in DMF media showing metal centered reduction processes for both of them. The redox properties, nature of the electrode processes and the stability of the complexes were discussed. [Cu(MAPT)2]Cl2 complex shows Cu(Ⅱ)/Cu(Ⅰ) couple and quasi-reversible wave associated with the Cu(Ⅲ)/Cu(Ⅱ) process. The reduction/oxidation potential values depend on the structures of complexes. Also, the antimicrobial activities of these complexes were determined against S. aureus, E. coli and B. subtilis.  相似文献   

11.
The stability constants for the formation of [Cu(tet a)X]+(blue) from [Cu(tet a)]2+(blue) and X- (where X=Cl, Br, I) were determined by spectrophotometric method at 15°, 25° and 35°C. The corresponding ΔH° and ΔS° values were obtained from the variations of the stability constants between 15° and 35°C. For the same halide ion, the stability constant of [Cu(tet b)X]+ (blue) is larger than that of [Cu(tet a)X]+(blue).  相似文献   

12.
Comparative study of the regularities of the reaction and specific features of phase formation during electrochemical incorporation of lithium from propylene carbonate solutions in intermetallic aluminum-based compounds (CuAl2, Mg2Al3, and NiAl) and pure metals (Al, Cu, Mg, and Ni) was performed. The initial stage of the process was shown to be dissolution of lithium in the solid phase limited by diffusion for all studied substrates. Trace amounts of lithium-containing by-products, were detected in NiAl, Ni, and Cu samples. The subsequent change in the limiting stage is related to the beginning of formation of a new phase: metallic lithium (on Mg2Al3, NiAl, Mg, Ni, and Cu) or LiAl (on Al and CuAl2 cathodes). In the latter case, the solid-phase substitution occurs, which is formally described by the equation: CuAl2+2Li++2e→2LiAl+Cu. Thus, the specific features of phase formation on the CuAl2 electrode correspond to the highest (among three intermetallides studied) concentration of Al atoms in the crystal lattice of the compound. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8. pp. 1525–1530, August, 1998.  相似文献   

13.
In this work, bamboo charcoal (BC) was used as a sorbent for on-line solid phase extraction (SPE) coupling with flame atomic absorption spectrometry (AAS) for trace copper and zinc determination in environmental and biological samples. Under the optimum pH of 5.5 (for Zn) and 7.0 (for Cu), trace copper and zinc were effectively adsorbed on the microcolumn and the retained cations were efficiently eluted with HCl or HNO3 with an appropriate concentration and flow rate for on-line AAS determination. With a sample loading time of 60 s at a sample flow rate of 7.6 mL min?1, the enhancement factors of 39 (for Cu) and 30 (for Zn) and detection limits (3σ) of 0.60 µg L?1 (for Cu) and 0.36 µg L?1 (for Zn), respectively, were achieved. The sample throughput was 45 h?1. At the level of 20 µg L?1of Cu(II) and Zn(II), the precision (RSD, n?=?11) were found to be 0.26% and 1.6%, respectively. The proposed method has been successfully applied to the determination of copper and zinc in environmental and biological samples.  相似文献   

14.
Copper complexes of the type Cu(L)4(H2PO4)2 designated as complex (I), and Cu(L)4 HPO4 designated as complex (II), (whereL = pyridine (py) or λ-picoline (pic)) have been synthesised, characterised by chemical analyses, IR, and electronic and magnetic susceptibility data. From ESR studies it is concluded that complexes (I) have elongatedtrans octahedral stereochemistry. The temperature dependence of the ESR spectrum of Cu(py)4(H2PO4)2 suggests a fluxional behaviour in the immediate coordination of Cu(II), whereas very little variation of the ESR spectrum of the Cu(pic)4(H2PO4)2 complex indicates that the stereochemistry of this complex is essentially static in nature. The differential scanning calorimetric studies in the case of Cu(py)4(H2PO4)2 complex have given clear evidence for the occurrence of a structural phase transition at 147 K. The absence of any abrupt changes in the ESR spectrum at that temperature excludes the possibility of any changes in the immediate environment of Cu(II).  相似文献   

15.
Firstly, poly[phenyl thiadiazole methacrylamide-co-divinylbenzene-co-2-acrylamido-2-methylpropane sulfonic acid] (PTMAAm-co-DVB-co-AMPS), a new polymer resin was synthesized. This polymer resin was characterized by elemental analyzer, X-ray diffractometer, scanning electron microscope (SEM) and IR spectrometer. The glass column packed with the synthesized polymer resin was used for solid phase extraction (SPE). At the same time, the analytes were separated and preconcentrated from various water, dried vegetables samples and standard reference material (CRM) with SPE and determined by flame atomic absorption spectrometer (FAAS). The experimental conditions of this method such as pH, flow rates of sample, flow rates of eluent, type / concentration / volume of eluent, sample volume and matrix ions were examined. The limits of detection (µg L?1) were calculated (3s) 0.9 for Mn(II), 1.4 for Cd(II), Co(II) and Zn(II), 1.5 for Cr(III), 2.2. for Cu(II), 1.9 for Pb(II),1.5 for Ni(II) and 1.9 for Fe(III) (n = 21). The low relative standard deviation, ≤ 2% (n = 11) and preconcentration factor as 75 for analytes were obtained.  相似文献   

16.
A Cu(II) complex of a Schiff base obtained by the condensation of N,N-dimethyl-1,4-phenylenediamine with 3,5-di-tert-butyl-2-hydroxybenzaldehyde has been synthesized and characterized. The structure of the complex was determined by single-crystal X-ray methods. The four-coordinate Cu(II) ion possesses a compressed tetrahedral coordination environment.  相似文献   

17.
《Analytical letters》2012,45(10):1967-1980
Abstract

The analysis of random errors is discussed for the equilibrium constants of very stable metal complexes, determined through competitive potentiometric methods. Prior to this analysis the calculation of standard deviations both for overall and stepwise equilibrium constants is considered. Clues are given as to how a system can be properly characterized. To illustrate the error analysis, the following systems were selected: Cu(II) and L-2,6-diaminohexanoic acid (L-lysine); Cu(II) and ethylene diaminotetraacetic acid (EDTA); and Cu(II), EDTA and 1,2-dihydroxybenzene (catechol).  相似文献   

18.
以粗糙铜箔为基底, 采用一步电沉积法获得Cu-Sn合金, X射线衍射(XRD)测试结果显示其主要为Cu6Sn5合金相. 扫描电子显微镜(SEM)测试结果表明该合金表面由大量“小岛”组成, 且每个“小岛”上存在大量纳米合金粒子. 充放电测试结果表明, 以该合金为锂离子电池负极, 其初始放电(嵌锂)和充电(脱锂)容量分别为461和405 mAh&#8226;g-1. 电化学阻抗谱测试结果显示, Cu6Sn5合金电极在阴极极化过程中分别出现了代表固体电解质界面膜(SEI膜)阻抗、电荷传递阻抗和相变阻抗的圆弧, 并详细分析了它们的变化规律.  相似文献   

19.
《先进技术聚合物》2018,29(1):151-159
Super porous gum Arabic (GA) cryogels were synthesized by crosslinking of natural GA with divinyl sulfone at cryogenic conditions, −20°C for potential biomedical applications. Humic acid (HA) nanoparticles were also prepared by using degradable and biocompatible crosslinkers such as trimethylolpropane triglycidyl ether, poly(ethylene glycol) diglycidyl ether, and trisodium trimetaphosphate in a single step and then entrapped within GA cryogel network as GA/HA particle cryogel. Furthermore, GA/HA cryogel was used as a template for Ag, Cu, and Fe nanoparticle preparation, and their antimicrobial properties were tested against Escherichia coli, Staphylococcus aureus, and Bacillus subtilis strains. The minimum inhibition concentration values of Ag and Cu nanoparticle‐loaded GA/HA cryogel composites were determined as 10 mg mL−1. Furthermore, the blood compatibility tests such as hemolysis and blood clotting indexes were determined for GA cryogels and found to be more compatible with 0.08 ± 0.01% hemolysis and 89.4 ± 6.1 blood clotting values, whereas the hemolysis of the Ag, Cu, and Fe nanoparticle‐loaded GA/HA Ag, Cu, and Fe metal nanoparticle cryogel composites decreased in the order of Fe > Cu > Ag nanoparticles.  相似文献   

20.
Monolithic porous copolymers with 3D structure were prepared via CO2‐in‐water high internal phase emulsions template by graft copolymerization of sodium methacrylate (MAANa) on to methyl cellulose (MC) backbone. The yielded copolymer monoliths are characterized by Fourier transform infrared spectra, scanning electron microscopy (SEM), and mechanical instrument, the swelling degree of MC‐g‐PMAANa monoliths with different crosslinker in diverse pH were investigated. The adsorption performance of monolith to Cu(II) were conducted to explore its adsorption capacity to heavy metal ions from the wastewater. Then, a strategy of in situ growth of metal‐organic frameworks (MOFs) on MC‐g‐PMAANa that adsorbed with metal ions was proposed first. The X‐ray powder diffraction, SEM, and Brunauer‐Emmett‐Teller (BET) surface area result of MC‐g‐PMAANa/MOFs composites indicated that the MOFs nanoparticles were grown uniformly on the monolith wall without destroying its original 3D porous structure. Compared with MOFs nanoparticle, MC‐g‐PMAANa/MOFs composites have advantages of easy operation and handle, which more conform to practical application. Furthermore, the antibacterial activity of MC‐g‐PMAANa/MOFs was evaluated by disk agar diffusion and optical density methods. In addition, MC‐g‐PMAANa/Cu‐BTC composite was applied to dye adsorption, which has proved the underlying application of such composites in dye removal.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号