Deposition of lead

Crude lead contains traces of a number of metals. The desilvering of lead is considered later under silver (Chapter 14). Other metallic impurities are removed by remelting under controlled conditions when arsenic and antimony form a scum of lead(II) arsenate and antimonate on the surface while copper forms an infusible alloy which also takes up any sulphur, and also appears on the surface. The removal of bismuth, a valuable by-product, from lead is accomplished by making the crude lead the anode in an electrolytic bath consisting of a solution of lead in fluorosilicic acid. Gelatin is added so that a smooth coherent deposit of lead is obtained on the pure lead cathode when the current is passed. The impurities here (i.e. all other metals) form a sludge in the electrolytic bath and are not deposited on the cathode. 

Deposits of lead sulfate slowly build up on the plates, partially covering and replacing the lead and lead dioxide. 

Before use, electrodes must be carefully cleaned to remove any previous deposits. Deposits of copper, silver, cadmium, mercury, and many other metals can be removed by immersion in dilute nitric acid (1 1), rinsing with water, then boiling with fresh 1 1 nitric acid for 5-10 minutes, followed by a final washing with water. Deposits of lead dioxide are best removed by means of 1 1 nitric acid containing a little hydrogen peroxide to reduce the lead to the Pb(II) condition ethanol or oxalic acid may replace the hydrogen peroxide. 

Cathodic deposition of lead sulfide from acidic aqueous solutions of Pb(II) ions (nitrate salts mainly) and Na2S203 on various metallic substrates at room temperature has been reported. Stoichiometric PbS films composed of small crystallites (estimated XRD diameter 13 nm) of RS structure were obtained at constant potential on Ti [204]. Also, single-phase, polycrystalline thin films of RS PbS were electrode-posited potentiostatically on Ti, Al, and stainless steel (SS) [205]. It was found that the Al and Ti substrates promoted growth of PbS with prominent (200) and (111)... 

Ivanov DK, Osipovich NP, Poznyak SK, Streltsov EA (2003) Electrochemical preparation of lead-doped amorphous Se films and underpotential deposition of lead onto these films. Surf Sci 532-535 1092-1097... 

Streltsov EA, Poznyak SK, Osipovich NP (2002) Photoinduced and dark underpotential deposition of lead on selenium. 1 Electroanal Chem 518 103-114... 

Grgur BN, Markovic NM, Ross PN. 1997. Underpotential deposition of lead on Pt(lll) in perchloric acid solution RRDpt(in)E measurements. Langmuir 13 6370-6374. 

Sources of lead in surface water or sediment include deposits of lead-containing dust from the atmosphere, waste water from industries that handle lead (primarily iron and steel industries and lead producers), urban runoff, and mining piles. 

Wolff MS Mount Sinai School of Medicine of CUNY, New York, NY Analytical support for comprehensive assessment of lead exposures body burden measures will include blood lead, plasma lead, ZPP, bone lead, representing multiple compartments for deposition of lead and widely variable rates of elimination measurement of total lead in soil extracts to validate quantitative measures National Institute of Environmental Health Sciences... 

Rao RV, Chowdhury AR, Chinov NJ. 1987. Deposition of lead in reproductive organs of male rats following, the administration of lead acetate. Curr Sci 56 281-282. 

Mulvaney P, Giersig M, Henglein A (1992) Surface chemistry of colloidal gold deposition of lead and accompanying optical effects. J Phys Chem 96 10419-10424... 

Batley [780] found that in situ deposition of lead and cadmium on a mercury-coated tube was the more versatile technique. The mercury film, deposited in the laboratory, is stable on the dried tubes which are used later for field electrodeposition. The deposited metals were then determined by electrothermal AAS. 

Batley [28] examined the techniques available for the in situ electrodeposition of lead and cadmium in estuary water. These included anodic stripping voltammetry at a glass carbon thin film electrode and the hanging drop mercury electrode in the presence of oxygen and in situ electrodeposition on mercury coated graphite tubes. Batley [28] found that in situ deposition of lead and cadmium on a mercury coated tube was the more versatile technique. The mercury film, deposited in the laboratory, is stable on the dried tubes which are used later for field electrodeposition. The deposited metals were then determined by electrothermal atomic absorption spectrometry, Hasle and Abdullah [29] used differential pulse anodic stripping voltammetry in speciation studies on dissolved copper, lead, and cadmium in coastal sea water. 

Liu, D. D. H. Mevissen, J. P. 1997. Thick layer deposition of lead perovskites using diol-based chemical solution approach. Int. Ferro. 18(l-4) 263-274. 

Kanniainen, T. Lindroos, S. Leskela, M. 1995. Deposition of lead sulfide thin films by successive ionic layer and reaction-technique. Adv. Sci. Technol. 5 291-298. 

Determination of lead in 70 pL samples of whole blood can be carried out in a few minutes by a procedure including treatment with a matrix-modifying solution containing hydrochloric acid, Hg(II) ions, Triton X-100 and Bi(III) as internal standard. After deposition of lead amalgam on a glassy carbon electrode by a pulsed potential cycle, analysis... 

In the Mississippi River system, naturally occurring deposits of lead ores and effluents from zinc producers and industrial dischargers were prevalent. 

To confirm this idea two examples are given in Figures 18(a) and (b) ecosystem-dependent depositions of lead in South Norway and in Central Spain in 2002. Depositions are split in wet and dry. Wet deposition fluxes are assumed to be the same for different types of ecosystems. Annual precipitation amounts in these regions are about 1,400 (Norway) and 510 (Spain) mm. In the Norwegian region dry deposition to forests is higher than that to arable lands. However, due to the large amount of precipitation, wet deposition prevails and total deposition (sum of wet and dry) does not differ much between forests and arable lands. 

The atmospheric deposition of lead was 190 g/ha/yr and this value was connected with declining of leaded petrol use in USA from 1975. The mineral soil and forest floor were the major pools of Pb in the ecosystem. Mineral soil pools (<2 mm size fraction) are generally the largest element pools for the HBEF, however this includes relatively unreactive soil minerals. Deposition and accumulation of Pb in the forest floor have been the focus of a number of investigations. It has been shown that at... 

The underpotentlal deposition of lead has been examined on LEED-characterized single crystal silver surfaces with 0.1 M HF as the electrolyte using a special ultra-high vacuum-electrolyte transfer system. Each of the low index surfaces has a characteristic voltammetry curve with multiple adsorption and desorption UPD peaks. 

Figure 2. Voltammograms for the underpotential deposition of lead on silver single crystal surfaces.

The authors acknowledge very helpful discussions with Dr. R. Adzic of the Institute of Electrochemistry, Belgrade, concerning the underpotential deposition of lead on single crystal silver substrates after chemical polishing. The authors also acknowledge support of the research by the U.S. Office of Naval Research. 

Electrolyte chemistries continue to be discovered and need to be carefully controlled, e.g., there is a need to track nitric acid molarity as well as total acid molarity in the catholyte to avoid silver deposition, and the deposition of lead dioxide on cell electrodes and in electrode cavities, which has required the development of a formic acid wash. 

Lead is the 35th most abundant element on Earth. Although it has been found in its free elemental metal state, it is usually obtained from a combination of the following ores galena (PbS), anglesite (PbSO ), cerussite (PbCOj), and minum (Pb O ). Lead ores are located in Europe (Germany, Rumania, and France), Africa, Australia, Mexico, Peru, Bolivia, and Canada. The largest deposits of lead in the United States are in the states of Missouri, Kansas, Oklahoma, Colorado, and Montana. 

Electrodeposition and Underpotential Deposition of Lead on Solid Substrates... 

Properties of thin layers of lead electrodeposited on vitreous carbon have been found identical with that of metallic lead [304]. Therefore Pb and Pb02 coated reticulated vitreous carbon (RVC) electrodes [185] can be applied as electrodes in lead-acid batteries, as reviewed in [305]. The deposition of lead on carbon is through the diffusion-controlled process with instantaneous or progressive nucleation, for high and low Pb + concentration, respectively, and three-dimensional growth mechanism. The number of nucleation sites increases with deposition overpotential, as shown for vitreous [306] and glassy carbon [307] electrodes. The concentration dependence of the nucleation... 

Little, P. and R. D. Wiffen. Emission and deposition of lead from motor exhausts. II. Airborne concentration, particle size and deposition of lead near motorways. Atmos. Environ. 12 1331-1341 (1978). 

As before, the subscript s denotes solid phases, and the subscript aq denotes solvated ions in solution. As a result of this process, a deposit of lead metal is formed on the electrode surface at the end of the cathodic scan while CO2 diffuses to the... 

In some cases, the deposit of lead metal also consist of irregular aggregates far from the original particles of the lead compound [126], as can be seen in Fig. 2.10 for minium (Pb304)—another widely used pigment These features can be rationalized, assuming that the electrochemical pathway represented by Eq. 2.6 can eventually be coupled by a reductive process via formation of Pb + in solution... 

An important factor that influences the lead distribution, especially in the channeled monolith bodies, is the character of flow. There is strong evidence that an induced change of the flow from laminar to turbulent augments the deposition of lead. An example is given in Fig. 7 by the deposition pattern of lead in a dual catalyst. Within each of the catalysts, the deposit pattern is in agreement with those shown in Figs. 4 and 5. However, the lead deposit on the inlet of the oxidation catalyst exceeds con-... 

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