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A new kind of inorganic composite adsorbent based on chitin whiskers(CHW) and potassium tetratitanate whiskers(PTW) was synthesized via the thermal deposition to remove Cu2+ and Pb2+ from wastewater. CHW could be successfully coated on the surface of PTW when thermal treated 8 times. The adsorption process was better fitted with the Langmuir and Freundlich models. The adsorption process was more conformed to the Pseudo-second-order model. The results from XPS(X-ray photoelectron spectrum) further show that the adsorption mechanism between CHW-PTW and Cu2+, Pb2+ are both ion exchange and chemical adsorption. Thermodynamic parameters suggest that the adsorption processes are nonspontaneous. The adsorption of Cu2+ and Pb2+ is endothermic and exothermic, respectively. 相似文献
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Dr. Marian Olaru Daniel Duvinage Dr. Enno Lork Dr. Stefan Mebs Prof. Dr. Jens Beckmann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(65):14758-14761
Fluoride abstraction from bis-m-terphenylelement fluorides (2,6-Mes2C6H3)2EF (E=P, As) generated the highly reactive phosphenium ion [(2,6-Mes2C6H3)2P]+ and the arsenium ion [(2,6-Mes2C6H3)2As]+, which immediately underwent intramolecular electrophilic substitution and formation of an 1,2,4-trimethyl-6-mesityl-5-m-terphenyl-benzo[b]phospholium ion and an 1,2,4-trimethyl-6-mesityl-5-m-terphenyl-benzo[b]arsolium ion, respectively. The formation of the latter involved a methyl group migration from the ortho-position of a flanking mesityl group to the meta-position. This reactivity of [(2,6-Mes2C6H3)2E]+ (E=P, As) is in sharp contrast to the related stibenium ion [(2,6-Mes2C6H3)2Sb]+ and bismuthenium ion [(2,6-Mes2C6H3)2Bi]+, which have been recently isolated and fully characterized (Angew. Chem. Int. Ed. 2018, 57 , 10080–10084). On the basis of DFT calculations, a mechanism for the rearrangement of the phosphenium and arsenium ions into the phospholium and arsolium ions is proposed, which is not feasible for the stibenium and bismuthenium ions. 相似文献
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以一道北京高考题为切入点,利用标准电极电势计算Ag++Fe2+=Ag+Fe3+的平衡常数和电动势。运用能斯特方程,计算非标准状态下该反应的电动势,理论上证实逆反应可以实现。设计原电池装置,通过改变离子浓度,实现电流表指针的反转,验证该氧化还原反应确有可逆性。 相似文献
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Kuznetsov V. V. Pavlov M. R. Zimakov D. I. Chepeleva S. A. Kudryavtsev V. N. 《Russian Journal of Electrochemistry》2004,40(7):711-715
An incomplete reduction of molybdate ions in solutions of pH 3.0–9.0 is shown to be accelerated by ammonium ions: a film of hydrated oxides of molybdenum in lower oxidation states forms on the cathode in their presence. Products of the incomplete reduction adsorbed at the cathode block its working surface. 相似文献
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《液相色谱法及相关技术杂志》2012,35(14):3213-3234
Abstract The use of ethylenediaminetetraacetic acid, disodium salt, (pH 3-5) has been investigated as an eluant for the separation and detection of nanogram levels of selected divalent and trivalent metal ions. The effect of pH and eluant concentration upon the retention times and resolution of the system are given and the ability to alter the eluant characteristics to optimize the chromatographic results in different situations will be discussed. The method is less complicated than the method frequently used for transition metal ion determinations which uses a post-column derivitization reagent. This method is applicable to a wider range of metal ions and provides detection limits which are generally within two orders of magnitude of the post-column derivitization method. 相似文献
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Dr. Agnes Kütt Prof. Dr. Gunnar Jeschke Dr. Lauri Toom Dr. Jaak Nerut Prof. Christopher A. Reed 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(41):8871-8874
Hydride abstraction from diarylamines with the trityl ion is explored in an attempt to generate a stable diarylnitrenium ion, Ar2N+. Sequential H-atom abstraction reactions ensue. The first H-atom abstraction leads to intensely colored aminium radical cations, Ar2NH.+, some of which are quite stable. However, most undergo a second H-atom abstraction leading to ammonium ions, Ar2NH2+. In the absence of a ready source of H-atoms, a unique self-abstraction reaction occurs when Ar=Me5C6, leading to a novel iminium radical cation, Ar=N.+Ar, which decays via a second self H-atom abstraction reaction to give a stable iminium ion, Ar=N+HAr. These products differ substantially from those derived via photochemically produced diarylnitrenium ions. 相似文献
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Dr. Marian Olaru Artem Schröder Dr. Lena Albers Daniel Duvinage Dr. Stefan Mebs Prof. Dr. Jens Beckmann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(42):9861-9865
Efforts to prepare an elusive donor-free phosphenium ion, [R2P]+, led us to synthesize functionalized fluorophosphonium cations of the type [R2P(F)X]+ (X=SiEt3, H, F), which were obtained from the related neutral fluorophosphines R2PF and R2PF3 upon protonation and reaction with solvated [Et3Si]+ ions (R=2,6-Mes2C6H3). The hypothetical reductive elimination of [R2P(F)SiEt3]+ and [R2P(F)H]+ affording [R2P]+, Et3SiF and HF, respectively, was calculated to be endothermic by 40.1 and 190.6 kJ mol−1. 相似文献
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Ronald E. Leone Paul von R. Schleyer 《Angewandte Chemie (International ed. in English)》1970,9(11):860-890
Carbonium ions are called “degenerate” when they rearrange through finite energy barriers to give products whose gross structures are identical with those of the starting ions. In such degenerate rearrangements (“automerizations”), individual atoms and groups become mixed but the overall structure is conserved. Automerizations can be observed by noting the dispersal of isotopic labels, the loss of optical activity, or the temperature dependence of NMR spectra. In certain cases, a combination of well-known rearrangement processes results in complete mixing of all atoms, C or H. The 2-norbornyl and 9-barbaralyl cations are examples of fully degenerate systems; conditions can be found where both give but single-line NMR spectra. 相似文献
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Negative Hydration of Ions 总被引:1,自引:0,他引:1
The negative hydration, that is the increase in the mobility of water molecules near sufficiently large single-charged ions, is studied by modeling, cold-neutron scattering, and computer modeling. Special attention is paid to the mechanism of negative hydration and the boundary of transition from positive to negative and from negative to hydrophobic hydration. Hypothetical ions with radii of approximately 1.1 and 3.3 Å correspond to these boundaries. Dynamic characteristics of hydration water in these ions are identical to those of water molecules in bulk water. 相似文献
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适用于痕量金属离子迁移的微乳状液的制备及其迁移条件 总被引:6,自引:1,他引:6
研究了以气溶胶OT为表面活性剂与不同烃类的油性溶剂及不同醇类的助表面活性剂一起制备的油包水型微乳为Cd62+从水相或料相迁移到微乳中的影响,同时还观察了油水比和温度对金属离子迁移的影响,从而确定了适于痕量金属离子迁移的微乳体系和和Cd^2+为规范离子的迁移条件。 相似文献
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硒代蛋氨酸与铜离子的相互作用(英文) 总被引:2,自引:0,他引:2
采用循环伏安法和库仑法研究了硒代蛋氨酸(SeMet)与铜离子的相互作用.当SeMet不存在时,铜离子在-132和71mV有一对氧化还原峰(峰Ⅴ,Ⅵ).当铜离子与SeMet共存时,配合物在14,128,271,-194mV有4个峰(峰Ⅰ,Ⅱ,Ⅲ,Ⅳ).扫描电位从600mV到-600mV时,Cu(Ⅱ)-(SeMet)2配合物在14mV时被还原为Cu(I)-SeMet配合物;Cu(Ⅰ)-SeMet配合物在-194mV被还原为Cu(0)和SeMet.由-600mV回扫时,还原产物被逐次氧化为Cu(Ⅰ)-SeMet配合物(128mV)和Cu(Ⅱ)-(SeMet)2配合物(271mV).同时发现Cu(Ⅰ)-SeMet配合物在电位-100mV至200mV间是稳定的,Cu(Ⅰ)的氧化还原过程被观察到.此外,采用毛细管电泳法测得二元Cu-SeMet配合物的稳定常数(K1和K2)分别为2.24×107和2.24×106.最后,推测Cu-SeMet配合物的结构为:在pH3.9时,铜离子通过Cu—Se和Cu—OCO键与SeMet发生配位作用;在生理条件时,铜离子通过Cu—N和Cu—OCO键与SeMet发生配位作用. 相似文献
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V. P. Yurkinskii E. G. Firsova N. V. Petrova 《Russian Journal of Applied Chemistry》2005,78(8):1370-1372
Complexation of lead(II) ions with hydroxide ions in nitrate-chloride solutions at 298 K was studied using potentiometric titration. 相似文献
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Kilpatrick LE Neta P Yang X Simón-Manso Y Liang Y Stein SE 《Journal of the American Society for Mass Spectrometry》2012,23(4):655-663
Tandem mass spectra of peptide ions, acquired in shotgun proteomic studies of selected proteins, tissues, and organisms, commonly
include prominent peaks that cannot be assigned to the known fragmentation product ions (y, b, a, neutral losses). In many
cases these persist even when creating consensus spectra for inclusion in spectral libraries, where it is important to determine
whether these peaks represent new fragmentation paths or arise from impurities. Using spectra from libraries and synthesized
peptides, we investigate a class of fragment ions corresponding to yn-1 + 10 and yn-1 + 11, where n is the number of amino acid residues in the peptide. These 10 and 11 Da differences in mass of the y ion were
ascribed before to the masses of [+ CO – H2O] and [+ CO – NH3], respectively. The mechanism is suggested to involve dissociation of the N-terminal residue at the CH-CO bond following
loss of H2O or NH3. MS3 spectra of these ions show that the location of the additional 10 or 11 Da is at the N-terminal residue. The yn-1 + 10 ion is most often found in peptides with N-terminal proline, asparagine, and histidine, and also with serine and threonine
in the adjacent position. The yn-1 + 11 ion is observed predominantly with histidine and asparagine at the N-terminus, but also occurs with asparagine in positions
two through four. The intensities of the yn-1 + 10 ions decrease with increasing peptide length. These data for yn-1 + 10 and yn-1 + 11 ion formation may be used to improve peptide identification from tandem mass spectra. 相似文献