Lead Carboxylate Research Articles

One-pot and high-yield preparation of ultrathin β-PbO nanowires and nanosheets for high-capacity positive electrodes in lead-acid batteries

To obtain high-capacity electrode materials and meanwhile actualize the reuse of scrap lead paste, a novel alkylamine-mediated thermolysis route is proposed herein for one-pot preparation of high-quality PbO nanomaterials, relying on the thermal decomposition of lead carboxylate in hot solvent in the presence of hexadecylamine (HDA). This synthetic route allows us to produce uniform PbO nanowires with a diameter of 7.1 nm and a length beyond 10 μm, and nanosheets and nanorings with a lateral size of ca. 310 nm on a gram scale, by simply tuning the alkylamine content or reaction time. In particular, we have employed various means to unveil the key role of HDA, i.e., precursor activation and surface passivation function, in the controlled preparation of such PbO nanomaterials. Impressively, when serving as the positive active materials for lead acid batteries (LABs), the anodes based on PbO nanowires displayed an excellent discharge performance: its discharge capacity and active material utilization ratios could reach 164.3 mA h/g and 68.5% respectively even at a discharge current density as high as 50 mA/g, which are superior to most of the previously-reported values. Such an excellent discharge performance was speculated to result from the synergization effect of the large ECSA, small charge transfer resistance and highly active exposed facets associated with the PbO nanowires.

Absorption edge sensitive radiography and tomography of Egyptian Papyri

Abstract In the Egyptian Museum and Papyrus Collection, Berlin, a multitude of papyrus manuscripts are stored. Papyri found on Elephantine island are of special interest. No other settlement in Egypt has been so well documented through texts over four millennia. However, 80% of the Elephantine texts are yet to be documented and published. As part of the “Elephantine” project, funded by an ERC starting grant, we attempt to gain access to hidden text. Most of the fragments are very fragile, deformed, with some rolled or folded. Papyri from the Old and Middle Kingdom were typically written with carbon ink. Consequently, these fragments show no absorption sensitivity for hard X-rays. Also, other inks have been used in those times. If small traces of high-Z elements, like Fe or Pb, are found, absorption may be sensitive enough for radiography and tomography to distinguish between writing and base material. We sorted out suitable fragments and papyrus packages by X-ray fluorescence mapping. When promising high-Z elements were detected, absorption tomography was applied using micro-CT laboratory systems or synchrotron X-rays at the BAMline at BESSY II. The sensitivity can be enhanced by element-sensitive absorption edge imaging, where transmission data taken above and below the edge are compared. This technique was applied at the absorption edges of the elements known to be used as ink and pigment material – Iron, Antimony and Lead. These X-ray results were complemented by Fourier-transform infrared spectroscopy (FT-IR) measurements showing that the lead is found in the form of lead carboxylate. In the future, the presented methodology will be applied to folded or rolled papyri, allowing for analysis of the text without manually opening the fragments.

Conservation of contemporary art: Alteration phenomena in a XXI century artwork. From contactless in situ investigations to laboratory accelerated ageing tests

Abstract The present study reports the results of a combined approach in investigating the alteration phenomena on a contemporary artwork, Senza Titolo, by Nunzio di Stefano. The oeuvre, created in 2001, is composed by seven lead carved panels coated with Paraloid B72. After having being stored for several years in wood boxes, it was acquired in 2015 and, only at that time, the surface showed an evident deterioration In situ analyses, by means of contactless external reflection infrared spectroscopy (ERFTIR), have shown that the alterations products are in the form of basic lead carbonate and, surprisingly, of lead carboxylate. The presence of these products were supposedly due to VOCs attack during the storage in wood boxes. The formation of lead carboxylate, due to the interaction among lead substrate and acetic and formic acids (the major components of the VOCs mixture), was investigated through a laboratory accelerated ageing. The effect of VOCs was studied on the lead substrate, on the acryl coating and on a series of mockups simulating Senza Titolo. The combination of surface and punctual analyses, by means of ERFIR and μ-FTIR, showed that the formation of alteration products is a relatively fast process. The alteration path involves firstly the absorption of VOCs moisture on the Paraloid B72 surface, immediately followed by corrosion processes, leading to hydrocerussite, lead acetate and formate. The presence of the polymeric coating controls the transformation of lead carboxylates to basic lead carbonate. Laboratory results have consolidated those obtained by in situ contactless investigations, confirming ERFTIR as powerful tool in assessing the state of conservation of Cultural Heritage materials.

The Use of a Saturated Long Carbon Chain Sodium Monocarboxylate for the Corrosion Inhibition of Lead Objects in Atmospheric Conditions and in Acetic Acid Corrosive Solutions

In this paper, a saturated long carbon chain sodium monocarboxylate containing 18 carbons—labeled NaC18—was used for the formation of a lead carboxylate coating to inhibit the corrosion of lead in atmospheric conditions and in acetic acid corrosive solutions. The effect of stirring of the coating solution during the coating process on the inhibition efficiency was studied. The coating was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy which have confirmed a formation of lead carboxylate layer on the lead metal surface. The corrosion inhibition properties of the coating were tested using linear sweep voltammetry and electrochemical impedance spectroscopy in a solution simulating the atmospheric conditions and in an acetic acid corrosive solution. Results show that the lead carboxylate forms a protective barrier that inhibits corrosion of lead in atmospheric conditions and in acetic acid corrosive solutions.

Further advances in lead carboxylate coatings: coating unprimed heritage lead

Further to the previously published work in this journal “Towards a new coating for heritage lead”, a coating has been trialled with samples replicating aged lead artefacts. Lead was corroded in an oak environment to simulate storage or display in a wooden case then coated with ethanolic solutions of tetradecanoic and octadecanoic acid. X-ray diffraction and electrochemical impedance data suggests an better-quality coating is formed leading to improved corrosion resistance.

Discovery of non-competitive thrombin inhibitor derived from competitive tryptase inhibitor skeleton: Shift in molecular recognition resulted from skeletal conversion of carboxylate into phosphonate.

A novel series of terminal and internal phosphonate esters based on our previously developed aryl carboxylate-type tryptase selective inhibitor 1 was synthesized. The potency of these synthesized compounds was assessed in vitro with an enzyme inhibition assay using three available serine proteases, that is, tryptase, trypsin, and thrombin. The internal phosphonate derivative 6 showed potent thrombin inhibitory activity with an IC50 value of 1.0 μM, whereas it exhibited no or only weak tryptase and trypsin inhibition at 10 μM. The Lineweaver-Burk plot analysis indicates that the inhibition pattern of thrombin with 6 is non-competitive in spite of the fact that the lead carboxylate compound 1 is competitive inhibitor. Therefore, the skeletal conversion of the carboxylate into a phosphonate alters the mode of molecular recognition of these inhibitors by thrombin.

Coordination geometry of lead carboxylates - spectroscopic and crystallographic evidence.

Despite their versatility, only a few single-crystal X-ray structures of lead carboxylates exist, due to difficulties with solubility. In particular, the structures of long-chain metal carboxylates have not been reported. The lone electron pair in Pb(ii) can be stereochemically active or inactive, leading to two types of coordination geometries commonly referred to as hemidirected and holodirected structures, respectively. We report (13)C and (207)Pb solid-state NMR and infrared spectra for a series of lead carboxylates, ranging from lead hexanoate (C6) to lead hexadecanoate (C18). The lead carboxylates based on consistent NMR parameters can be divided in two groups, shorter-chain (C6, C7, and C8) and longer-chain (C9, C10, C11, C12, C14, C16, and C18) carboxylates. This dichotomy suggests two modes of packing in these solids, one for the short-chain lead carboxylates and one for long-chain lead carboxylates. The consistency of the (13)C and (207)Pb NMR parameters, as well as the IR data, in each group suggests that each motif represents a structure characteristic of each subgroup. We also report the single-crystal X-ray diffraction structure of lead nonanoate (C9), the first single-crystal structure to have been reported for the longer-chain subgroup. Taken together the evidence suggests that the coordination geometry of C6-C8 lead carboxylates is hemidirected, and that of C9-C14, C16 and C18 lead carboxylates is holodirected.

Hydrogenated Dimer Acid as a Corrosion Inhibitor for Lead Metal Substrates in Acetic Acid

The surface characteristics of a lead carboxylate coating induced on a lead substrate using a dimer acid are discussed together with its effectiveness against acetic acid corrosion. Thermogravimetric analysis and differential scanning calorimetry were used to examine the thermal properties of the hydrogenated dimer acid and its corresponding sodium salt. Scanning electron microscopy with energy-dispersive spectroscopy, X-ray photoelectron spectroscopy and infrared spectroscopy were used to visualize and characterize the deposited coatings on the lead substrate. Both the free dimer acid and the corresponding sodium salt formed a protective layer of lead carboxylate complexes through a reaction with the lead substrate. Single-sine electrochemical impedance spectroscopy and potentiodynamic polarization measurements of the bare and coated samples assessed the corrosion resistance of the coatings. Under the corrosive acetic acid test conditions, the lead-dimer-coated samples corroded more slowly than the bare lead.

Towards a new method for coating heritage lead

BackgroundEthanolic solutions of long-chain carboxylic acids can be applied to lead metal substrates to form a coating of lead carboxylate which provides protection against atmospheric pollutants.Results and conclusionsIn this paper we describe the optimal inhibitor concentration for the coating on lead. Electrochemical impedance data taken before and after immersion in media modelling oak emitted volatile organic compounds (VOCs) polluted atmospheres show that coating effectiveness decreases after exposure, but the effect is lessened if longer chain carboxylates are used.

Hexameric Octahedral Clusters of PbSe Nanocrystals Grown from Amorphous Lead(II) Carboxylate Nanoparticles

We describe the synthesis and three-dimensional structure of a new single-crystalline “hexameric” nanocrystal composed of six near-spherical PbSe nanocrystals arranged at the vertices of an octahed...

Combustion synthesis of PbO from lead carboxylate precursors relevant to developing a new method for recovering components from spent lead–acid batteries

AbstractBACKGROUND: In the conventional recycling process, lead battery pastes are recovered as metallic lead by using an energy intensive decomposition and reduction process. Decomposition of PbSO4 requires the use of relatively high temperature and causes environmental pollution, i.e. emission of SO2 and lead particulates. A new process for treating the pastes at low temperature has been developed.RESULTS: Three major lead compounds are individually reacted with an aqueous solution of citric acid in order to leach and to crystallize lead citrate precursors, which are then subjected to calcination at relatively low temperatures to recover the lead directly as PbO the most common active material for preparing pastes for a new battery. Characterization of the citrate precursors have been carried out using DSC, XRD, and SEM. The combustion products were characterized by XRD and SEM.CONCLUSION: Lead(II) oxides along with a small amount of lead metal are the combustion products, which can be produced at a relatively low temperature of 350 °C. Resulting morphologies show that combustion products are in the 100–200 nm size range, providing high‐surface‐area PbO for making new battery paste materials. The work is aimed to develop a sustainable process for recovering lead from spent lead battery paste. Copyright © 2012 Society of Chemical Industry

Ethylene glycol-mediated synthesis of PbO nanocrystal from PbSO 4: A major component of lead paste in spent lead acid battery

Lead sulfate (PbSO 4) is a major component of lead paste of spent lead acid batteries, normally over 60%. In traditional pyrometallurgical process, the decomposition of PbSO 4 requires a relatively high temperature and the use of coal as both the reducing agent and as the source of thermal energy, thereby causing emissions of SO x , lead particles and CO 2. In this study, lead sulfate was desulfated by adding an aqueous solution comprising citric acid and tri-sodium citrate with the modulation of ethylene glycol (EG) in order to control the morphology. The treating agent reacted with lead sulfate to form an aqueous solution of sodium sulfate and a precipitated precursor of lead carboxylate crystals. The precursor was characterized by XRD, SEM, SDT and FTIR. The morphology of the EG-mediated precursor showed a regular columnar shape. On calcining at relatively low temperatures, EG-mediated precursor was transformed into fine particles of lead oxide. The characteristics of calcined products were investigated by XRD, SEM, and TEM. The results showed that nanostructured crystals of lead oxide could be easily prepared by combustion of EG-mediated precursor at 350 °C with a lead recovery of about 98%. This paper has paved the way for obtaining nanostructured PbO from waste battery scrap.

Synthesis of Monodisperse Superconducting Lead Nanocrystals

We report on a new organic-phase synthesis method to produce a large quantity of high-quality monodisperse population of superconducting lead (Pb) nanocrystals. They are obtained from the alcohol reduction of a mixture of lead oleate and lead acetate in the presence of trioctylphosphine in octadecene. We show that the details of lead carboxylate mixture preparation is the key parameter in controlling the nucleation rate of the synthesis. Because mixtures of metal carboxylate have been widely used in synthesizing various high-quality metals or metal−oxide nanocrystals, the results herein should contribute to the understanding of the detailed mechanisms of these syntheses. Because of the large quantities provided by this synthesis, these nanocrystals are particularly well adapted for studies of the effect of quantum confinement on superconductivity.

Size-tunable near-infrared PbS nanoparticles synthesized from lead carboxylate and sulfurwith oleylamine as stabilizer

High quality PbS nanocrystals are synthesized reproducibly through lead stearate andsulfur stabilized by oleylamine in a non-coordinating solvent. The morphology,crystalline form and phase composition of PbS nanocrystals are examined bytransmission electron microscopy (TEM), high-resolution TEM, x-ray diffraction(XRD), energy-dispersive x-ray spectroscopy (EDS) and x-ray photoelectronspectroscopy (XPS). The as-synthesized PbS nanocrystals have strong absorptionand photoluminescence emissions in the near-infrared region. The size of PbSnanocrystals from 5 to 13 nm can be adjusted through the optimization of the synthesisconditions. The smaller PbS nanoparticles are obtained at the lower reactiontemperature, lower precursor concentration, larger oleylamine quantity and larger leadprecursor/sulfur ratio. The basic oleylamine enhances the reactivity of both lead stearate precursor andsulfur precursor in the reaction.

Growth and real time corrosion resistance monitoring of lead decanoate coatings

Lead is very susceptible to corrosion in the presence of organic acids and humidity. A potential countermeasure is to apply a lead carboxylate coating by immersing the metal in a sodium carboxylate solution/suspension. In this work we report on the degree of surface coverage and the corrosion resistance of a lead decanoate Pb(C 10) 2 coating as a function of treatment time. Results show that the surface coverage reaches 91% after 15 min and about 100% after 1 h in a 0.05 M sodium decanoate solution. The corrosion resistance, as indicated by electrochemical impedance spectroscopy, continues to increase even after 6 h of immersion. In addition, we show that in the case of planar transport, a diffusion layer of 17 mm thickness exists, wherein the sodium decanoate concentration drops linearly from its bulk value to almost zero at the solid/surface interface.

Novel lead(II) carboxylate–arsonate hybrids

Hydrothermal reactions of lead(II) acetate with phenylarsonic acid (H 2L 1) (or 4-hydroxy-3-nitrophenylarsonic acid, H 3L 2) and 5-sulfoisophthalic acid monosodium salt (NaH 2SIP) (or 1,3,5-benzenetricarboxylic acid (H 3BTC)) as the second metal linkers afforded three novel mixed-ligand lead(II) carboxylate–arsonates, namely, Pb 5(SIP) 2(L 1) 2(H 2O) 1, Pb 3(SIP)(L 2)(H 2O) 2 and Pb(H 2L 2)(H 2BTC) 3. The structure of 1 features a complicated 3D network composed of 2D double layers of lead(II) sulfoisophthalate bridged by 1D chains of lead(II) arsonates along b-axis, forming large tunnels along b-axis which are occupied by phenyl rings of the arsonate ligands. In 2, the Pb(II) ions are bridged by {L 2} 3− anions into a 2D double layer whereas the interconnection of the Pb(II) ions via bridging and chelating SIP anions gave a 2D double layer. The cross-linkage of the above two building units leads to a complicated 3D network. In 3, the interconnection of the Pb(II) ions via bridging {H 2L 2} − and {H 2BTC} − anions leads to a 1D double chain down a-axis. These 1D chains are further interconnected via hydrogen bonds among non-coordination carboxylate groups and arsonate oxygens into a 3D supramolecular architecture.

Influence of the lead carboxylate on the molecular composition of its solutions with zirconium and titanium isopropoxides or n-butoxides: 2-ethylhexanoate vs acetate, a way to stabilize the first Pb-Zr carboxylatoalkoxides of 1:1 stoichiometry

The reactions between titanium or zirconium alkoxides namely Ti(OR)4 (R = iPr, nBu) or Zr2(OiPr)8(HOiPr)2, Zr(OnBu)4 respectively and lead 2-ethylhexanoate Pb(O2CC7H15)2 were investigated at room temperature (rt) and by heating. The various compounds were characterized by elemental analysis, FT-IR, 1H and 207Pb NMR. The mixed-metal species obtained at rt were adducts Pb4Zr4(μ-O2CR′)8(OR)16(OHR)21 and Pb2Ti4(μ-O2CR′)4(OR)162 (R′=CHCHEt(CH2)2Me, R = iPr) independently of the stoichiometry used. The structures of 1 and 2 are based on triangular M2Pb cores (M = Zr, Ti). with 6-coordinate transition metals -as required for perovskites- and 6- or 7-coordinate lead atoms. Similar observations were made with n-butoxides. Thermal and hydrolytic condensation reactions were investigated. Thermal condensation was more difficult for the n-butoxide derivatives than for the isopropoxide ones. Powders derived from the hydrolysis of the Single Source Precursor 1 in various conditions were characterized by TGA, XRD and SEM for the PZ ceramic.

Interplay between lead carboxylate and Ti or Zr isopropoxides in solution routes to perovskites: synthesis, molecular structures and reactivity of single source non-oxo Pb–Zr and Pb–Ti carboxylatoalkoxides supported by 2-ethylhexanoate ligands

The reactions between Ti(O(i)Pr)(4) and Zr(2)(O(i)Pr)(8)(HO(i)Pr)(2), respectively, and lead 2-ethylhexanoate Pb(O(2)CC(7)H(15))(2) have been investigated at rt and by heating. The initial mixed-metal species, characterized by single-crystal X-Ray diffraction, were adducts namely Pb(4)Zr(4)(mu-O(2)CR')(8)(mu-OR)(6)(mu(3)-OR)(2)(OR)(8)(OHR)(2) and Pb(2)Ti(4)(mu-O(2)CR')(4)(mu-OR)(6)(mu(3)-OR)(2)(OR)(8) (R' = CHCH(Et)C(2)H(4)Me, R = (i)Pr) independently of the stoichiometry used. They are the first Pb-Ti and Pb-Zr non-oxo carboxylatoalkoxides reported. is also the first Pb-Zr species based on an alkoxide-carboxylate ligand set matching the PbZrO(3) stoichiometry. Both structures are centrosymmetric with six-coordinate transition metals, as required for the perovskite, and are based on triangular M(2)Pb cores (M = Zr, Ti). The lead centers display quite high coordination numbers, six and seven. The thermal and hydrolytic condensation reactions of and were investigated. Heat treatment of and elimination of the volatiles under vacuum afforded Pb(2)Ti(3)(mu(4)-O)(mu(3)-O)(mu-O(2)CC(7)H(15))(2)(mu-O(i)Pr)(6)(O(i)Pr)(4) resulting from extrusion of Ti(O(i)Pr)(4) and scrambling of carboxylate ligands. Characterization of the various compounds was achieved by elemental analysis, FT-IR, (1)H and (207)Pb NMR.

Two new layered lead(II) diphosphonates with 1,3,5-benzenetricarboxylate ligands as an intercalated species or a multidentate metal linker

Hydrothermal reactions of lead(II) carbonate with 1,3,5-benzenetricarboxylic acid (H 3BTC) and butylimino-bis(methylenephosphonic acid) (CH 3CH 2CH 2CH 2N(CH 2PO 3H 2) 2, H 4L 1) or lead(II) acetate with H 3BTC and isobutylimino-bis(methylenephosphonic acid) (Me 2CHCH 2N(CH 2PO 3H 2) 2, H 4L 2) afforded two novel lead(II) carboxylate phosphonate hybrids, namely, Pb 5(HL 1) 2(L 1)·H 3BTC 1 and Pb 4(BTC)(L 2)(CH 3CO 2)(H 2O) 2·1.5H 2O 2. The structure of compound 1 contains a <002> lead(II) diphosphonate hybrid layer formed by Pb(II) ions interconnected by HL 1 and L 1 anions. In compound 2, the interconnection of Pb(II) ions through bridging diphosphonate L 2 anions lead to the formation of the <200> lead(II) diphosphonate 2D layer. In compound 1, the 1,3,5-benzenetricarboxylic acid acts as an intercalated species whereas in compound 2, the 1,3,5-benzenetricarboxylate anion adopts a hexadentate chelating and bridging coordination mode.

Solution behaviour of lead(II) carboxylates in organic solvents

The solution behaviour has been studied of a series of even chain length lead(II) carboxylates (octanoate to octadecanoate) and the odd chain length lead(II) heptadecanoate in a variety of non-complexing organic solvents and in alcohols. In agreement with previous studies, solubility increases dramatically above a certain temperature, which depends on solute concentration, chain length and solvent. This solution temperature is also affected by traces of water. These results are complemented by studies using vapour pressure osmometry, dynamic light scattering, 1H and 13NMR spectroscopy. The results in water-free systems are consistent with the formation of rather ill-defined, polydisperse aggregates, which increase in size with concentration and decrease with temperature. These show similar local structure to lamellar mesophases in the pure lead(II) carboxylates, and are suggested to be formed by solvent induced swelling and break-up of these mesophases. In the presence of water, a more ordered structure is formed, in which a few water molecules are suggested to be bound to the lead(II) carboxylate headgroup.