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1.
Lilian L. Lorencetti Yoshitaka Gushikem Lauro T. Kubota Graciliano de Oliveira Neto João R. Fernandes 《Mikrochimica acta》1995,117(3-4):239-244
A potentiometric sensor for the perchlorate anion was developed by mixing chemically modified silicagel with pyridinium perchlorate, with an epoxy polymer and graphite. The electrode showed Nernstian response between 1.0 × 10–2 and 1.0 × 10–3
M perchlorate concentrations. The electrode showed high selectivity to this ion at solutions pH between 5.5 and 8.0. The presence of IO
4
–
, NO
3
–
,Br–, IO
3
–
, Cl– and SO
4
2–
ions in the solutions, had only small interference in the electrode response in the range mentioned. 相似文献
2.
Jal PK Dutta RK Sudarshan M Saha A Bhattacharyya SN Chintalapudi SN K Mishra B 《Talanta》2001,55(2):233-240
Organic ligand with carboxyhydrazide functional group was immobilised on the surface of silica gel and the metal binding capacity of the ligand-embedded silica was investigated. The functional group was covalently bonded to the silica matrix through a spacer of methylene groups by sequential reactions of silica gel with dibromobutane, malonic ester and hydrazine in different media. Surface area value of the modified silica was determined. The changes in surface area were correlated with the structural change of the silica surface due to chemical modifications. A mixture solution of metal ions [K(I),Cr(III),Co(II),Ni(II),Cu(II),Zn(II),Hg(II) and U(VI)] was treated with the ligand-embedded silica in 10(-3) M aqueous solution. The measurement of metal extraction capacity of the silica based ligand was done by multielemental analysis of the metal complexes thus formed by using Proton Induced X-ray Emission (PIXE) technique. 相似文献
3.
Qihui Wang Zheng Hu Dandan Li Zhifeng Tu 《International journal of environmental analytical chemistry》2013,93(11):1289-1301
A chelating matrix prepared by immobilising folic acid on silica gel-bound amine phase was used as a new solid-phase extractant. This sorbent has been developed only for preconcentration of trace Pb(II) prior to determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Experimental conditions were investigated by batch and column procedures. The optimum pH value for the separation of Pb(II) on the new sorbent was 4.0. The adsorbed Pb(II) was quantitatively eluted by 2.0?cm3 of 0.5?mol?dm?3 of HCl. Common coexisting ions did not interfere with the separation and determination of Pb(II). The maximum static adsorption capacity of the sorbent under optimum conditions was found to be 69.23?mg?g?1 for Pb(II). The detection limit of the method defined by International Union of Pure and Applied Chemistry was 0.28?ng?cm?3. The relative standard deviation (RSD) of the method was lower than 2.0% (n?=?8). The developed method has been validated by analysing certified reference materials and successfully applied to the determination of Pb(II) in water samples with satisfactory results. 相似文献
4.
3-Hydroxy-2-methyl-1,4-naphthoquinone-immobilized silica gel has been used for the adsorption and estimation of copper, cobalt, iron and zinc by both batch and column techniques. The distribution coefficient D determined for each metal ion was as follows (ml g1): Fe, 3.6 × 102; Cu, 3.9 × 102; Co, 3.8 × 102; Zn, 4.1 × 102. Methods have been developed to estimate zinc, copper and cobalt in milk, steel and vitamin samples respectively. 相似文献
5.
Summary After summarizing published results on silica gel and alkyl-bonded silica gel solubilities, the experimental solubility of unmodified silica and copper silicate gel (used in ligand exchange chromatography) in watermethanol-ammonia and water-acetonitrile-ammonia mixtures are given. These results demonstrate that silica gel solubility, measured by a static method, varies greatly with the water volume fraction of a ternary mixture. Curiously, no influence from the organic nature of the solvent was demonstrated. This observation is inconsistent with the fact that the copper silicate gel used in ligand-exchange chromatography with water-methanol-ammonia as mobile phase is attacked more rapidly than with water-acetonitrile-ammonia.An explanation based upon the variations of acid-base properties of silicic acid versus mobile phase dielectric constant values in conjunction with the methanol protophilic properties is proposed. Finally, it is shown that chromatographic columns filled with copper silicate gel have lifetimes of several months, if they are used with a procolumn (of copper silicate gel) and with acetonitrile as organic solvent with a volume fraction greater than 0.5 in the mobile phase. 相似文献
6.
Urbirajara Pereira Rodrigues Filho Yoshitaka Gushikem Fred Yukio Fujiwara Eduardo Stadler Valderez Drago 《Structural chemistry》1994,5(2):129-133
Pentacyanoferrate(II) absorbed on a silica gel surface previously modified with 3-aminopropyl and 3-imidazolylpropyl groups were characterized by13C MAS/NMR, FT-IR, Mössbauer spectroscopy, and cyclic voltammetry. FT-IR and13C MAS/NMR data indicated that the pentacyanoferrate(II) complex is bonded to the surface by the nitrogen atom of the functional group. The differences in the isomeric shifts, the quandrupole splittings and the midpoint potentials of the adsorbed complexes in comparison with the model complexes were attributed to the matrix polar effect—i.e., the interaction of the complex with polar groups on the silica surface. 相似文献
7.
8.
Newton L. Dias Filho 《Mikrochimica acta》1999,130(4):233-240
The isotherms of adsorption of MeX2 (Me = Cu2+, Co2+; X = Cl–, Br–, ClO
4
–
) by silica gel chemically modified with 2-mercaptoimidazole (SiMI) were studied in acetone and ethanol solutions, at 25 °C. Covalently attached 2-mercaptoimidazole molecule to silica gel surface adsorbs MeX2 from solvent by forming a surface complex. The metal is bonded to the surface through the nitrogen atom of attached 2-mercaptoimidazole. At low loading, the electronic and ESR spectral parameters indicated that the Cu2+ complexes are in a distorted-tetragonal symmetry field. The d-d electronic transition spectra showed that for Cu(ClO4)2 complex, the peak of absorption did not change for any degree of metal loading and for Cl– and Br– complexes, the peak maxima shifted to higher energy with lower metal loading. The CoX2(X = Cl–, Br–, ClO
4
–
) analogues possess a distorted-tetrahedral field. 相似文献
9.
The adsorption isotherms of MCl(2) (M Mn, Ni, Cu, Zn and Cd) and FeCl(3) by silica gel chemically modified with benzimidazole molecules ( Si(CH(2))(3)NC(7)H(5)N) were studied in ethanol solution at 298 K. A column made of modified silica was used to adsorb and preconcentrate the above metal ions from ethanol solution. Elution was done with 0.1 M hydrochloric acid in an ethanol/water mixture having a mole fraction of water of 0.8. The material was applied in the preconcentration of metal ions from commercial ethanol normally used as engine fuel. 相似文献
10.
M. Odlyha R. P. W. Scott C. F. Simpson 《Journal of Thermal Analysis and Calorimetry》1993,40(3):1197-1212
Thermogravimetric analysis of silica gel has shown that the loss in weight between 30° and 910°C can be quantitatively explained on the basis of water being lost from three distinct and different populations of sites on the silica gel surface. The results indicate that the site energies of the three different populations are randomly distributed and, consequently, the resulting weight loss steps from each population can be described by the integral of a simple normal distribution with temperature. The calculated weight loss obtained by assuming three different site-groups having randomly distributed adsorption energies is, within experimental error, coincident with the experimental data. It is also shown that the water evolved from the second population of sites originates from strongly bound water and may also contain water generated by the condensation of (geminal) silanol groups contained in the overlapping and neighbouring population. 相似文献
11.
FAN Jing ZHU GuiFen WANG HaiBo & WANG JianJi Henan Key Laboratory for Environmental Pollution Control Key Laboratory for Yellow Huai River Water Environmental Pollution Control Ministry of Education School of Chemical Environmental Sciences Henan Normal University Xinxiang China 《中国科学B辑(英文版)》2011,(6)
Trace of Pb(Ⅱ) has been on-line separated and enriched from environmental samples and wastewater by using the self-made alizarin violet functionalized silica gel micro-column coupling with a sequential injection sampling technology. The determination is based on the color reaction of Pb(Ⅱ) with iodide and crystal violet to form an ionic association complex in the presence of polyvinyl alcohol and hydrochloric acid. The use of the microcolumn can prevent the interference of most familiar metal ions, and ther... 相似文献
12.
The efficiency for the extraction of U(VI) of new modified silica gels, namely N-tripropionate (or N-triacetate)-substituted tetraazamacrocycles-bound silica gels, has been studied. The effect of the nature of the ligand, the pH and the temperature was studied both in batch experiments as well as in continuous extraction. These silica gels are good candidates for the extraction of U(VI) when compared to a commercially available acid-type chelating resin. The breakthrough and regeneration tests showed that the total removal of U(VI) from a contaminated solution can be achieved by using a column packed with such tetraazamacrocycles-bound silica gels. Finally, the use of a modified silica gel in a pilot device allowed the total decontamination of 50 m3 of real effluents containing traces of uranium, plutonium, and americium. 相似文献
13.
Iwona Rykowska Wiesław Wasiak 《International journal of environmental analytical chemistry》2013,93(15):1466-1476
This paper describes our research on the synthesis of the sorbent with chemically bonded ketoimine groups, and, furthermore, using this sorbent in the SPE technique to extract and preconcentrate trace amounts of metal ions in water samples. Surface characteristics of the sorbent were determined by elemental analysis, NMR spectra for the solid phases (29Si CP MAS NMR), and analysis of pore size distribution of the sorbent and nitrogen adsorption-desorption. The newly proposed sorbent with ketoimine groups was applied for the extraction and preconcentration of trace amounts of Cu (II), Cr (III) and Zn (II) ions from the water from a lake, post-industrial water and purified water unburdened back to the lake. The determination of the transition-metal ions was performed on an emission spectroscope with inductively coupled plasma ICP-OES. For the batch method, the optimum pH range for Cu (II) and Cr (III) extraction was equal to 5, and Zn(II)–to 8. All the metal ions can be desorbed from SPE columns with 10?mL of 0.5?mol?HNO3. The detection limits of the method were found to be 0.7?µg?L?1 for Cu (II), 0.08?µg?L?1 for Cr (III), and 0.2?µg?L?1 for Zn (II), respectively. 相似文献
14.
Trace metals in water were preconcentrated with silica gel modified with salicylaldoxime and determined by AAS. Optimum conditions for the maximum recovery of metal ions, viz. Cu(II), Ni(II), Co(II), Zn(II) and Fe(III), for both batch and column methods were developed. The efficiency of the adsorbent with respect to different experimental conditions was established. 相似文献
15.
Hanyong Peng Nan Zhang Man He Beibei Chen 《International journal of environmental analytical chemistry》2016,96(3):212-224
A novel adsorbent of multi-wall carbon nanotubes (MWCNTs) chemically modified silica (MWCNTs-silica) was synthesised and employed as the adsorbent material for solid-phase extraction (SPE) of trace Zn(II), Cu(II), Cd(II), Cr(III), V(V) and As(V) in environmental water samples followed by inductively coupled plasma optical emission spectrometry detection. This material inherits the advantages of nanomaterial MWCNTs and conventional silica with dual functional groups (–NH2 and –COOH), and avoid the problem of nanomaterial in SPE, such as high pressure. The factors affecting the separation and preconcentration of target elements such as pH, sample flow rate and volume, eluent concentration and volume were investigated. Under the optimised conditions, the detection limits for Zn(II), Cu(II), Cd(II), Cr(III), V(V) and As(V) were 0.27, 0.11, 0.45, 0.91, 0.55 and 0.67 μg L?1 with the relative standard deviations of 3.1, 5.9, 4.1, 4.0, 7.3 and 8.6% (c = 10 μg L?1, n = 7), respectively. The adsorption capacity of MWCNTs-silica was 26.6, 70.0, 13.8, 58.0, 20.0 and 20.0 mg g?1 for Zn(II), Cu(II), Cd(II), Cr(III), V(V) and As(V), respectively, and the prepared adsorbent could be reused more than 100 times. In order to validate the developed method, two certified reference materials of GSBZ50009-88 and GSBZ 50029-94 environmental waters were analysed and the determined values were in good agreement with the certified values. The developed method has been applied to the determination of trace elements in environmental water samples with satisfactory results. 相似文献
16.
Summary A simple procedure was developed for preparing wide pore (≦ 40nm) silicas from a common chromatographic silica gel. The effects
of various experimental conditions on pore size, pore volume, and surface area are discussed. The results show that under
controlled conditions a wide variety of wide pore silica packing materials can be prepared.
Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984 相似文献
17.
Summary Characteristics of silica gel dynamically modified with a bile acid derivative have been investigated in liquid chromatography. 3-[(3-cholamidopropyl) dimethylamonio]-1-propane-sulfonate (CHAPS) is selected as modifier. CHAPS possesses a quaternary ammonium group which can be attached to the silica gel surface by cation exchange. The stationary phase modified with CHAPS has been applied to the separation of 1,1-binaphthyl-2,2-diyl-hydrogen phosphate enantiomers.Dedicated to Professor Leslie S. Ettre on the occasion of his 70th birthday. 相似文献
18.
Silica gel chemically modified with mercaptopropyl groups extracts silver(I) from solutions in the acidity ranges from 4 M HNO3 to pH 8 and from 0.01 M HCl to pH 7. The time it takes to attain a sorption equilibrium is no more than 2 min; distribution coefficient is 1 × 105 cm3/g. Yellow-orange luminescence was produced in the adsorbent phase upon the UV irradiation of wet adsorbates cooled to the liquid-nitrogen temperature (77 K). This effect was used for the development of a procedure for the low-temperature sorption-luminescence determination of silver. The calibration graph was linear in the range 1–80 µg Ag per 0.1 g of adsorbent. The detection limit was 0.05 µg per 0.02 g of adsorbent. The relative standard deviation was no more than 6% for silver amounts higher than 5 µg.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 4, 2005, pp. 390–393.Original Russian Text Copyright © 2005 by Losev, Elsuf ev, Trofimchuk. 相似文献
19.
Silica gel was firstly functionalised with aminopropyltrimethoxysilane obtaining the aminopropylsilica gel (APSG). The APSG was reacted subsequently with morin yielding morin-bonded silica gel (morin-APSG). The structure was investigated and confirmed by elemental and thermogravimetric analyses, IR and (13)C NMR spectral studies. Morin-APSG was found to be highly stable in common organic solvents, acidic medium (<2molL(-1) HCl, HNO(3)) or alkaline medium up to pH 8. The separation and preconcentration of Ag(I), Au(III), Pd(II), Pt(II) and Rh(III) from aqueous medium using morin-APSG was studied. The optimum pH values for the separation of Ag(I), Au(III), Pd(II), Pt(II) and Rh(III) on the sorbent are 5.7, 2.2, 3.7, 3.7 and 6.8, giving rise to separation efficiencies of 43.9, 85.9, 97.7, 60.9 and 91.0%, respectively, where the activity was found to be >90% in the presence of acetate ion. The ion sorption capacity of morin-APSG towards Cu(II) at pH 5.5 was found to be 0.249mmolg(-1) where the sorption capacities of Ag(I) and Pd(II) were 0.087 and 0.121mmolg(-1) and 0.222 and 0.241mmolg(-1) at pH 2.2 and 5.7, respectively. This indicates a 1:1 and 1:2 morin/metal ratios at pH 2.2 and 5.7, respectively. Complete elution of the sorbed metal ions was carried out using 10mL (0.5molL(-1) HCl+0.01molL(-1) thiourea) in case of Au(III), Pd(II), Pt(II) and Rh(III) and 10mL 0.5molL(-1) HNO(3) in case of Ag(I). Morin-APSG was successfully employed in the separation and preconcentration of the investigated precious metal ions from some spiking water samples yielding 100-folds concentration factor. The relative standard deviation (R.S.D.) and the T-test (|t|(1)) were calculated. 相似文献
20.
B. Sreedhar P. Surendra Reddy C.S. Vamsi Krishna P. Vijaya Babu 《Tetrahedron letters》2007,48(44):7882-7886
The design and development of a silica gel anchored copper chloride heterogeneous catalyst for the synthesis of propargylamines using an amine, an aldehyde, and an alkyne through C-H activation in water is described. Both aliphatic and aromatic aldehydes and amines are used for the reaction. The catalyst was recovered quantitatively by simple filtration and reused several times. 相似文献