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1.
Summary Equilibria occurring during the dynamic ion exchange separation of metal ions were examined, and their effect on the chromatography of the metal ions was evaluated. Bonded reversed-phase silica, pure organic reversed phase, and silica columns were used to differentiate between the role of silica and the reverse phase. The results show that system peaks had the most important influence on the applicability of dynamic exchangers to quantitative metal ion determinations. The response of system peaks to sample composition (pH, ionic strength, matrix effects) was complicated and could not be predicted easily. Equilibria effects that can cause analytical errors were identified and recommendations for elimination of such errors are given.Dedicated to Professor S. R. Lipsky on the occasion of his 60th birthday. 相似文献
2.
J. M. Lopes F. Lemos E. Derouane F. Ramôa Ribeiro 《Reaction Kinetics and Catalysis Letters》1996,58(1):33-38
A series of HNaZSM-20 catalysts with a varying amount of sodium cations were studied. The samples were prepared by ion exchange starting with a NaZSM-20 sample. The observedammonium-sodium exchange efficiency was slightly higher for ZSM-20 than for Y zeolite. The HNaZSM-20 series presentedhigher cracking activities in then-heptane transformation than the corresponding HNaY series. A decrease in theselectivity for coke deposition with sodium removal was also observed. 相似文献
3.
El-Safty SA 《Journal of colloid and interface science》2008,319(2):477-488
Design of nanocatalysts for efficient heterogeneous catalytic systems is needed to high ingredients for environmental cleanup of organic pollutant species. Here, well-defined order NiO-silica monolithic catalysts with hexagonal P6mm and cubic Pm3n mesostructures were successfully fabricated by using an instant direct-templating method of lyotropic and microemulsion phases of Brij 76 (C18H37(OCH2CH2)10 OH, C18EO 10). Ordered hexagonal P6mm NiO/HOM-2 monoliths could be fabricated in lyotropic system of Brij 76 at phase composition domains of TMOS/Brij 76 (50 wt%). However, periodically ordered cubic Pm3n NiO-supported monoliths were synthesized in microemulsion system formed by addition of C12-alkane to the hexagonal phase domains. This synthetic strategy also revealed that the NiO particles were well-dispersed into the silicate pore surface matrices of mesostructures. Monolithic NiO-silica composites with 2D hexagonal and 3D cubic geometries and with large particle morphologies show promise to act as catalysts. The current study revealed evidence of the advantages of nanoscale pore geometry and shape, and particle morphology of the supported silica monoliths in the design of nanocatalysts that can efficiently enhance the catalytic functionality in terms of stability, reversibility and reactivity. Furthermore, a key finding in our study was that 2D hexagonal and 3D cubic mesostructured NiO-silica catalysts retained the specific activity towards the oxidation reaction even after several regeneration/reuse cycles. Significant study of the mechanistic cyclization of the organic reactant using the density functional (DFT) calculations provided evidence of the key components of conformations of the functional model during the formation of the oxidation product. 相似文献
4.
Rongjun Qu Changmei Sun Chunhua Wang Yanzhi Sun Meiyan Yu 《European Polymer Journal》2005,41(7):1525-1530
In order to explore the reuse properties of oxidized chelating resin containing sulfur after adsorption, two kinds of novel chelating resins, poly[4-vinylbenzyl-(2-hydroxyethyl)] sulfoxide (PVBSO) and poly[4-vinylbenzyl-(2-hydroxyethyl)] sulfone (PVBSO2), were synthesized using poly[4-vinylbenzyl-(2-hydroxyethyl)] sulfide (PVBS) as material. Their structures were confirmed by FTIR and XPS. The adsorption properties and mechanism for metal ions such as Au3+, Pt4+, Pd2+, Hg2+, Cu2+, Ni2+, Fe3+, Pb2+, Cd2+, and Zn2+ were investigated. Experimental results showed that PVBSO had good adsorption and selective properties for Au3+, Pd2+ and Cu2+ when the coexisting ion was Pt4+, Ni2+, Pb2+ or Cd2+. In the aqueous system containing Cu2+ and Pb2+ or Cu2+ and Cd2+, PVBSO2 only adsorbed Cu2+. The selective coefficients of PVBSO and PVBSO2 were αAu/Pt = 4.8, αAu/Pd = 11.8, αPd/Pt = 10.9, αCu/Ni = 2.5, αCu/Cd = 41.2, αCu/Pb = ∞, αCu/Ni = 3.0, αCu/Cd = ∞, αCu/Pb = ∞, respectively. 相似文献
5.
新型桥联双四面体簇合物的合成与表征 总被引:2,自引:0,他引:2
利用(μ3-CCO2Et)Co3(CO)9与单阴离子试剂[Mo(CO)3(η5-C5H4R)]-[R=H,C(O)Me]的反应合成了2个新的含CCo2Mo骨架的簇合物(μ3-CCO2Et)Co2Mo(CO)8(η5-C5H4R)[R=H(1);R=C(O)Me(2)],进而用其与双阴离子试剂{-M(CO)3[η5-C5H4C(O)]}2-1,4-C6H4[M=Mo,W]反应合成了4个双四面体簇合物{(μ3-CCO2Et)CoMoM(CO)7(η5-C5H4R)[η5-C5H4C(O)]}2-1,4-C6H4[M=Mo,R=H(3);M=Mo,R=C(O)Me(4);M=W,R=H(5);M=W,R=C(O)Me(6)].这6个化合物的C和H元素分析,IR,1HNMR等表征都与其结构一致.晶体X射线衍射分析表明,化合物2属单斜晶系,C2/c空间群,晶胞参数a=1.1264(3)nm,b=1.1879(3)nm,c=3.3565(10)nm,β=93.320(5)°,V=4.484(2)nm3,Z=8,Dc=1.867g·cm-3,F(000)=2480,R=0.0369,wR=0.1150. 相似文献
6.
张 《高等学校化学学报》1999,20(8):1172-1178
利用Co2(CO)8与[Cl3CC(O)OCH2]2的反应合成了以C(O)OCH2CH2OC(O)桥联两个Co3C四面体骨架为特征的新型双四面体簇合物[(CO)9Co3(μ3-C)C(O)OCH2]2(1);1与不同物质的量比的Na[M(CO)3C5H4R](M=Mo,W;R=H,C(O)Me)反应,得到一步交换的产物(CO)9Co3(μ3-C)C(O)OCH2CH2OC(O)(μ3-C)Co2M(CO)8(C5H4R)[M=Mo,R=H(2);M=Mo,R=C(O)Me(3);M=W,R=H(4);M=W,R=C(O)Me(5)]或两步交换的产物[(C5H4R)(CO)8Co2M(μ3-C)C(O)OCH2]2[M=Mo,R=H(6);M=Mo,R=C(O)Me(7);M=W,R=H(8);M=W,R=C(O)Me(9)].5或9分别与Na[Mo(CO)3C5H5]以12的物质的量比反应得到含一个手性四面体骨架(CoMoWC)的(C5H5)(CO)8Co2Mo(μ3-C)C(O)OCH2CH2O·C(O)(μ3-C)CoMoW(CO)7(C5H4C(O)Me)(C5H5)(10)或含两个手性四面体骨架(CoMoWC)的[(C5H5)(C5H4C(O)Me)(CO)7CoMoW(μ3-C)C(O)OCH2]2(11);对化合物1_11进行了CH元素分析、IR和1HNMR等表征.结果表明,在金属交换反应中处于不同簇环境下的Co(CO)3基团反应活性不同.对化合物1进行了晶体X射线衍射分析.化合物1的晶体属单斜晶系,P21/n(#14)空间群,晶胞参数a=0.933 0(2)nm,b=1.519 7(4)nm,c=1.178 3(4)nm,=91.16(2)°,Z=2,F(000)=972.分子结构呈中心对称. 相似文献
7.
杯[4]间苯二酚芳烃Schiff碱衍生物的合成及其离子萃取性能 总被引:1,自引:0,他引:1
通过控制条件,使两种乙氧基羰基甲氧基杯[4]间苯二酚芳烃2a和2b的酯基与1,6-己二胺的一个氨基反应形成酰胺3a和3b,剩余的一个氨基再与水杨醛反应,得到了相应的杯芳烃Schiff碱衍生物4a和4b,对其进行了金属离子的液-液萃取性能研究.结果表明,Schiff碱基团的引入能大大增强杯芳烃与金属离子的配位能力,而杯芳烃空腔的存在又能提高Schiff碱与金属离子的配位选择性. 相似文献
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9.
Brian D. Bowes Harun Koku Kirk J. Czymmek Abraham M. Lenhoff 《Journal of chromatography. A》2009,1216(45):7774-7784
Adsorption behavior is compared on a traditional agarose-based ion-exchange resin and on two dextran-modified resins, using three proteins to examine the effect of protein size. The latter resins typically exhibit higher static capacities at low ionic strengths and electron microscopy provides direct visual evidence supporting the view that the higher static capacities are due to the larger available binding volume afforded by the dextran. However, isocratic retention experiments reveal that the larger proteins can be almost completely excluded from the dextran layer at high ionic strengths, potentially leading to significant losses in static capacity at relevant column loading conditions. Knowledge of resin and protein properties is used to estimate physical limits on the static capacities of the resins in order to provide a meaningful interpretation of the observed static capacities. Results of such estimates are consistent with the expectation that available surface area is limiting for traditional resins. In dextran-modified media, however, the volume of the dextran layer appears to limit adsorption when the protein charge is low relative to the resin charge, but the protein–resin electroneutrality may be limiting when the protein charge is relatively high. Such analyses may prove useful for semiquantitative prediction of maximum static capacities and selection of operating conditions when combined with protein transport information. 相似文献
10.
There is continued interest in the development of stationary phases for protein chromatography that can provide high resolution at elevated flow rates of the mobile phase. When using porous particles, resolution and dynamic binding capacity decline rapidly as the flow rate is increased. Monolithic columns have been developed to overcome these limitations. However, there are difficulties in manufacturing homogeneous larger scale monoliths. In this paper we investigate the morphology and performance characteristics of columns based on new ion exchangers obtained by mechanically disrupting continuous beds of acrylamido-based polymeric media. Near colloidal suspensions of loose particles obtained with this procedure can be flow-packed in ordinary chromatography columns resulting in beds of unexpectedly high hydraulic permeability. Columns up to 2.2 cm in diameter were studied with both Q and S functionalized media. The hydraulic permeability and interparticle porosity of these columns were rather high. The permeabilities of the S and Q media were 1.5 x 10(-13) and 2.4 x 10(-13) m2, respectively, while the corresponding porosities were 60 and 70%. These porosity values are similar to those of monoliths, suggesting that these particles assemble under flow to give high-porosity bridged structures. The structure of these packed beds was further characterized by embedding small packed columns in resins and obtaining sections for microscopic observation. The sections reveal the presence of small aggregates of non-porous 1-3 microm particles, surrounded by flow channels several micrometers in size. The height equivalent to a theoretical plate under isocratic and gradient elution conditions and the dynamic binding capacity were determined for several proteins and were found to be virtually independent of flow. 相似文献
11.
XiaoBiJING ChaoGuoYAN JingSUN LiWANG LinAN 《中国化学快报》2004,15(12):1392-1394
A number of benzodioxane compounds were synthesized using the palladium-catalyzed etherification of aryl halides by employing triphenylphosphane ligands. This method was used as key step in the synthesis of isoamericanol A and isoamericanin A. 相似文献
12.
Terpolymers prepared by condensation of o cresol and urea with formaldehyde in presence of acid catalyst (2 M HCl) proved to be selective chelating ion exchange resins for certain metal ions. The molecular weights of the synthesised terpolymers were determined by GPC Technique. TGA analysis was employed to study the thermal stability and the kinetic data like activation energy of the terpolymer resins. Chelation ion exchange properties of these terpolymers were studied for Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Pb2+ and Cd2+ ions. A batch equilibrium method was employed in the study of the selectivity of metal ion uptake involving the measurements of distribution of a given metal ion between the polymer samples. The study was carried out over a wide pH range and in media of various ionic strengths. 相似文献
13.
14.
Litseaone A, isolated from the stem barks of Litsea rubescens and Litsea pedunculata, is a chalcone derivative with a novel spiro-epoxide moiety. The structural revision of litseaone A was achieved by the racemic synthesis of the proposed structure and the asymmetric synthesis of the revised structure. The major tautomeric structure of litseaone A and the relative stereochemistry at the epoxide carbon center were also clarified. 相似文献
15.
离子交换树脂在分析化学中的应用 总被引:1,自引:0,他引:1
简要评述了离子交换树脂在分析化学中的应用。包括离子交换树脂预富集技术从稀溶液中浓缩痕量离子,离子交换树脂相分光光度法测定微量离子,离子色谱在无机分析中的应用,以及离子交换树脂在有机分析与生化分析中的应用。 相似文献
16.
The synthesis,characterization,and its response to metal ions of a novel thiourea N,N’-diethoxycarbonyl-A",iV″’-(1,2- ethylidene) dithiourea was reported.The results show that this dithiourea with new structure can react with Cu2+ and Ni2+ separately,and has a best selectivity to Fe3+ ions.Bench-scale flotation tests were also carried out,verifying it has higher copper flotation recovery and better selectivity to sulfide ores containing Cu compared with universal collectors. 相似文献
17.
Synthesis of a novel calix[4]arene-based fluorescent ionophore and its metal ions recognition properties 总被引:1,自引:0,他引:1
A novel fluorescent ionophore derived from calix[4]arene and pyrazoline was designed and synthesized. Its molecular structure was confirmed by 1H NMR and element analysis. The resulting material shows specific fluorescent behavior toward the Zn2+ ion among the other divalent metal ions, such as Co2+, Ni2+, Cu2+. The primary results indicate this ionophore material is a potential material for developing efficient fluorescent Zn2+ chemosensors. 相似文献
18.
Metal exchange reactions of acetylacetonate complexes with Cd(II), Cu(II) and Zn(II) ions were investigated by using cadmium and copper ion selective electrodes. Changes in the electrode potential and pH of the solutions were monitored upon adding the pertinent metal Zn(II) of the acetylacetonate (AA) complexes. In the reverse system in which a stable Cu-AA complex exists in the solution prior to adding a secondary metal ion (Cd(II) or Zn(II)), no Cu(II) was replaced by either ion. In the systems containing Cd(II) and Zn(II) as a complexed form with AA or as free ions, the exchange reactions were not explained by considering the equilibrium stability constants of the Cd-AA and Zn-AA complexes. 相似文献
19.
L. Yu. Dolgikh I. L. Stolyarchuk P. E. Strizhak A. V. Shvets V. G. Il’in 《Theoretical and Experimental Chemistry》2006,42(1):37-42
The dependence of the activity and selectivity of ion-exchanged forms of zeolite X with incorporated cesium process in alkylation
of toluene with methanol in the side chain on the nature of the ion-exchanged cations (Na+, Cs+, Mg2+, Zn2+) has been established. It is shown that introduction of Mg2+ and Zn2+ in combination with Cs2CO3 significantly increased the yields of ethylbenzene and styrene in comparison with their yields on alkali forms of zeolite
X.
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Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 1, pp. 33–38, January–February, 2006. 相似文献