Pb2+ Ions (pb2+ + ion)

Distribution by Scientific Domains


Selected Abstracts


Structural characterization of hexoses and pentoses using lead cationization.

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 4 2002
An electrospray ionization, tandem mass spectrometric study
Abstract The analytical potential of the complexation of isomeric underivatized hexoses (D -glucose, D -galactose, D -mannose, D -talose, D -fructose), methylglycosides (1- O -methyl-,- D -glucose and 1- O -methyl-,- D -glucose) and pentoses (D -ribose, D -xylose, D -arabinose and D -lyxose) by Pb2+ ions, was investigated by electrospray ionization and tandem mass spectrometry (MS/MS). Pb2+ ions react mainly with monosaccharides by proton abstraction to generate [Pb(monosaccharide)m , H]+ ions (m = 1,3). At low cone voltage, a less abundant series of doubly charged ions of general formula [Pb(monosaccharide)n]2+ is also observed. The maximum number n of monosaccharides surrounding a single Pb2+ ion depends on the metal : monosaccharide ratio. Our study shows that MS/MS experiments have to be performed to differentiate Pb2+ -coordinated monosaccharides. Upon collision, [Pb(monosaccharide) , H]+ species mainly dissociate according to cross-ring cleavages, leading to the elimination of CnH2nOn neutrals. The various fragmentation processes observed allow the C(1), C(2) and C(4) stereocenters of aldohexoses to be characterized, and also a clear distinction aldoses and fructose. Furthermore, careful analysis of tandem mass spectra also leads to successful aldopentose distinction. Lead cationization combined with MS/MS therefore appears particularly useful to identify underivatized monosaccharides. Copyright 2002 John Wiley & Sons, Ltd. [source]


The role of Bi3+ -complex ion as the stabilizer in electroless nickel plating process

AICHE JOURNAL, Issue 4 2009
K. Wang
Abstract Bi3+ -complex ion is presented here as a less toxic stabilizer for use in electroless nickel plating (ENP) to replace the existing Pb2+ ion stabilizer. The asymmetric derivatives of EDTA are identified to be a type of coordination ligands that can combine with Bi3+ ions to form soluble complexes in the acidic ENP solution. In the ENP system studied the Bi3+ -complex ion displays a critical stabilizer concentration of about 10,5 mol/L, that is, the percolation concentration over which the ENP rate drops sharply. Besides the experimental measurement, deposition rates of both Ni and P are also simulated by using a kinetic model that has been derived from the double electric layer theory. The Bi3+ -complex ion, behaving like conventional Pb2+ ion, stabilizes ENP bath through the chemical replacement reaction at the surface of Ni deposition layer and results in a passive plating surface. This investigation also verifies the properties of the EN deposit, which are insignificantly affected by the length of service time of the plating solution by employing Bi3+ -complex ion stabilizer. 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]


Bismuth/Polyaniline/Glassy Carbon Electrodes Prepared with Different Protocols for Stripping Voltammetric Determination of Trace Cd and Pb in Solutions Having Surfactants

ELECTROANALYSIS, Issue 2 2010
M. Wang
Abstract To improve reproducibility, stability and sensitivity, a bismuth (Bi) thin film was coated on glassy carbon (GC) substrates which surfaces were modified with a porous thin layer of polyaniline (PANI) via multipulse potentiostatic electropolymerization to form Bi/PANI/GC electrodes (Bi/PANI/GCEs). The Bi/PANI/GCEs were used successfully for simultaneous detection and determination of Cd2+ and Pb2+ ions, and various parameters were studied with reference to square wave anodic stripping voltammetric (SWASV) signals. The experimental results depicted that the environment-friendly Bi/PANI/GCEs had the ability to rapidly monitor trace heavy metals even in the presence of surface-active compounds. [source]


A New Carrier for Selective Removal of Heavy Metal Ions from Aqueous Solutions through Bulk Liquid Membranes

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 18 2004
Nicoletta Spreti
Abstract The carrier-mediated transport of heavy metal ions through bulk liquid membranes has been examined: toxic Hg2+, Cd2+ and Pb2+ ions were studied, along with Cu2+ ions for comparative purposes. The ability of a new carrier, 2,2,-bis(p -octyloxybenzyl)diethylenetriamine (bis- pODET), to complex and transport all the selected metal ions is reported. Differing affinities of the carrier for the different metal ions and the different experimental conditions required for their release into the receiving phase allowed the selective separation of equimolar binary mixtures. For Hg2+/Cd2+ and Hg2+/Pb2+ mixtures, two different separation methods were performed, while the inefficacy of the separation of Cd2+/Pb2+ and Hg2+/Cu2+ mixtures was for two different reasons: (i) the carrier is able to extract the metal ions with similar levels of ability, and (ii) the carrier metal ion complexes require the same acidity of the receiving phase to release the metal ions. The capability of the carrier to transport Hg2+ efficiently in consecutive cycles is also reported: over 90% of the metal ions were transferred into the receiving phase for three consecutive processes. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]


Characterization of the glycosidic linkage of underivatized disaccharides by interaction with Pb2+ ions

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 8 2007
Ahlam El Firdoussi
Abstract Electrospray ionization in combination with tandem mass spectrometry and lead cationization is used to characterize the linkage position of underivatized disaccharides. Lead(II) ions react mainly with disaccharides by proton abstraction to generate [Pb(disaccharide)m, H]+ ions (m = 1,2). At low cone voltages, an intense series of doubly charged ions of general formula [Pb(disaccharide)n]2+ are also observed. Our study shows that MS/MS experiments have to be performed to differentiate Pb2+ -coordinated disaccharides. Upon collision, [Pb(disaccharide) , H]+ species mainly dissociate according to glycosidic bond cleavage and cross-ring cleavages, leading to the elimination of CnH2nOn neutrals (n = 2,4). The various fragmentation processes allow the position of the glycosidic bond to be unambiguously located. Distinction between glc-glc and glc-fru disaccharides also appears straightforward. Furthermore, for homodimers of D -glucose our data demonstrate that the anomericity of the glycosidic bond can be characterized for the 1 , n linkages (n = 2, 4, 6). Consequently, Pb2+ cationization combined with tandem mass spectrometry appears particularly useful to identify underivatized disaccharides. Copyright 2007 John Wiley & Sons, Ltd. [source]


Structural characterization of hexoses and pentoses using lead cationization.

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 4 2002
An electrospray ionization, tandem mass spectrometric study
Abstract The analytical potential of the complexation of isomeric underivatized hexoses (D -glucose, D -galactose, D -mannose, D -talose, D -fructose), methylglycosides (1- O -methyl-,- D -glucose and 1- O -methyl-,- D -glucose) and pentoses (D -ribose, D -xylose, D -arabinose and D -lyxose) by Pb2+ ions, was investigated by electrospray ionization and tandem mass spectrometry (MS/MS). Pb2+ ions react mainly with monosaccharides by proton abstraction to generate [Pb(monosaccharide)m , H]+ ions (m = 1,3). At low cone voltage, a less abundant series of doubly charged ions of general formula [Pb(monosaccharide)n]2+ is also observed. The maximum number n of monosaccharides surrounding a single Pb2+ ion depends on the metal : monosaccharide ratio. Our study shows that MS/MS experiments have to be performed to differentiate Pb2+ -coordinated monosaccharides. Upon collision, [Pb(monosaccharide) , H]+ species mainly dissociate according to cross-ring cleavages, leading to the elimination of CnH2nOn neutrals. The various fragmentation processes observed allow the C(1), C(2) and C(4) stereocenters of aldohexoses to be characterized, and also a clear distinction aldoses and fructose. Furthermore, careful analysis of tandem mass spectra also leads to successful aldopentose distinction. Lead cationization combined with MS/MS therefore appears particularly useful to identify underivatized monosaccharides. Copyright 2002 John Wiley & Sons, Ltd. [source]


Local structure of Pb (II) ion catalysts anchored within zeolite cavities and their photocatalytic reactivity for the elimination of N2O

JOURNAL OF SYNCHROTRON RADIATION, Issue 2 2001
Woo-Sung Ju
The Pb2+/ZSM-5 catalyst was prepared by an ion-exchange method and its photocatalytic activity for the decomposition of N2O under UV irradiation was investigated. In-situ UV-Vis absorption spectroscopy and XAFS (XANES and FT-EXAFS) investigations revealed that the Pb2+ ions exist in a highly dispersed state within the pores of the zeolites. UV irradiation of the catalysts in the presence of N2O led to the photocatalytic decomposition of N2O into N2 at temperatures as low as 298K. The effective wavelength of the irradiated UV light indicated that the excited state of the Pb2+ ions included within the zeolite cavities plays a significant role in the photocatalytic decomposition of N2O molecules. [source]


Spectroscopic and thermal studies of poly[(N -vinylimidazole)- co -(maleic acid)] hydrogel and its quaternized form

POLYMER INTERNATIONAL, Issue 4 2008
Nursel Pekel
Abstract BACKGROUND: In this study, poly[(N -vinylimidazole)- co -(maleic acid)] (poly(VIm/MA)) hydrogels were prepared by ,-irradiation of ternary mixtures of N -vinylimidazole,maleic acid,water using a 60Co ,-source. Spectroscopic and thermal analyses of these hydrogels as a function of protonation showed that the results are consistent with the existence of an H-bridged complex when the imidazole rings are partially protonated. Finally, the efficiency and binding trends of Cu2+, Co2+, Cd2+ and Pb2+ ions with both protonated and unprotonated poly(VIm/MA) hydrogels were determined. RESULTS: Gelation of 90% was reached at around 180 kGy dose at the end of irradiation. The poly(VIm/MA) hydrogels synthesized were further protonated in HCl solutions with different concentrations. Hydrogels originally showed 450% volumetric swelling; this ratio reached 1900% after protonation at pH = 5.0. Fourier transform infrared spectral changes in the +NH stretching region (3200,3600 and 1173 cm,1) and the ring mode deformation at 915 cm,1 are consistent with the formation of an H-bridged complex between the protonated and unprotonated imidazole rings upon partial protonation. Similar changes were obtained from NMR spectra of both the protonated and unprotonated forms of the hydrogels. CONCLUSION: Protonated and unprotonated hydrogels have been used in heavy metal ion adsorption studies for environmental purposes. Adsorption decreased with decreasing pH value due to the protonation of the VIm ring. The adsorption of Me2+ ions decreased in the order Cu2+ > Co2+ > Cd2+ > Pb2+, which is related to the complexation stability as well as the ionic radius of the metal ions. These results show that P(VIm/MA) hydrogels can be used efficiently to remove heavy metal ions from aqueous solutions. However, the protonated form is a bad choice for heavy metal ion adsorption due to electrostatic repulsion forces; it can nevertheless be assumed to be a good choice for anion adsorption from environmental waste water systems. Copyright 2007 Society of Chemical Industry [source]


Characterization of an unusual folding pattern in a catalytically active guanine quadruplex structure

BIOPOLYMERS, Issue 6 2006
Pinaki R. Majhi
Abstract In the presence of certain metal ions, DNA and RNA can form guanine quadruplex structures, which have been proposed to play a functional role in a variety of biological processes. An 18-nucleotide DNA oligomer, PS2.M, d(GTG3TAG3CG3T2G2), was previously reported to bind hemin and the resulting complex exhibited peroxidase activity. It was proposed that PS2.M folds unimolecularly into an antiparallel quadruplex with unusual, single-base loops and terminal guanines positioned in adjacent quartets. Here we describe structural and stability properties of PS2.M alone in different buffers and metal ions, using gel electrophoresis, circular dichroism (CD), ultraviolet (UV)-visible spectroscopies, and one-dimensional 1H nuclear magnetic resonance (NMR). Native gel behavior of PS2.M in the presence of either Na+ or Pb2+ suggests the formation of unimolecular structures but, in the presence of K+, both unimolecular and multistranded structures are observed. In the presence of Pb2+ ions, PS2.M forms a unimolecular quadruplex containing three guanine quartets. CD titrations reveal that binding of Pb2+ ions to PS2.M is stoichiometric, and a single lead cation suffices to fully fold PS2.M. The PS2.M,Na+ system also forms a similar unimolecular quadruplex. In the presence of K+, the PS2.M,K+ system forms mixed species. With increasing time and PS2.M concentration, the contribution of unimolecular species decreases while that of multimolecular species increases, and this behavior is independent of buffer media. These results suggest that the catalytically active form, studied in the presence of K+, may be a parallel, multistranded quadruplex rather than an antiparallel, unimolecular quadruplex. 2006 Wiley Periodicals, Inc. Biopolymers 82:558,569, 2006 This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source]


Rapid and Effective Adsorption of Lead Ions on Fine Poly(phenylenediamine) Microparticles

CHEMISTRY - A EUROPEAN JOURNAL, Issue 16 2006
Mei-Rong Huang Prof.
Abstract Fine microparticles of poly(p -phenylenediamine) (PpPD) and poly(m -phenylenediamine) (PmPD) were directly synthesized by a facile oxidative precipitation polymerization and their strong ability to adsorb lead ions from aqueous solution was examined. It was found that the degree of adsorption of the lead ions depends on the pH, concentration, and temperature of the lead ion solution, as well as the contact time and microparticle dose. The adsorption data fit the Langmuir isotherm and the process obeyed pseudo-second-order kinetics. According to the Langmuir equation, the maximum adsorption capacities of lead ions onto PpPD and PmPD microparticles at 30,C are 253.2 and 242.7 mg,g,1, respectively. The highest adsorptivity of lead ions is up to 99.8,%. The adsorption is very rapid with a loading half-time of only 2 min as well as initial adsorption rates of 95.24 and 83.06 mg,g,1 min,1 on PpPD and PmPD particles, respectively. A series of batch experiment results showed that the PpPD microparticles possess an even stronger capability to adsorb lead ions than the PmPD microparticles, but the PmPD microparticles, with a more-quinoid-like structure, show a stronger dependence of lead-ion adsorption on the pH and temperature of the lead-ion solution. A possible adsorption mechanism through complexation between Pb2+ ions and N groups on the macromolecular chains has been proposed. The powerful lead-ion adsorption on the microparticles makes them promising adsorbents for wastewater cleanup. [source]


General and Facile Syntheses of Metal Silicate Porous Hollow Nanostructures

CHEMISTRY - AN ASIAN JOURNAL, Issue 6 2010
Jun Zheng
Abstract Porous hollow nanostructures have attracted intensive interest owing to their unique structure and promising applications in various fields. A facile hydrothermal synthesis has been developed to prepare porous hollow nanostructures of silicate materials through a sacrificial-templating process. The key factors, such as the concentration of the free metal cation and the alkalinity of the solution, are discussed. Porous hollow nanostructures of magnesium silicate, nickel silicate, and iron silicate have been successfully prepared by using SiO2 spheres as the template, as well as a silicon source. Several yolk,shell structures have also been fabricated by a similar process that uses silica-coated composite particles as a template. As-prepared mesoporous magnesium silicate hollow spheres showed an excellent ability to remove Pb2+ ions in water treatment owing to their large specific surface and unique structures. [source]