Bismuth, deposition

Figure 7.6 Bismuth deposition on a Pt(775) electrode from 5 pM Bi + 0.5 M H2SO4 solution. The results have been divided into two graphs for the sake of clarity. Sweep rate 50mV/s.

Bismuth-film electrodes (BiFEs), consisting of a thin bismuth-film deposited on a suitable substrate, have been shown to offer comparable performance to MFEs in ASY heavy metals determination [17]. The remarkable stripping performance of BiFE can be due to the binary and multi-component fusing alloys formation of bismuth with metals like lead and cadmium [18]. Besides the attractive characteristics of BiFE, the low toxicity of bismuth makes it an alternative material to mercury in terms of trace-metal determination. Various substrates for bismuth-film formation are reported. Bismuth film was prepared by electrodeposition onto the micro disc by applying an in situ electroplating procedure [19]. Bismuth deposition onto gold [20], carbon paste [21], or glassy carbon [22-24] electrodes have been reported to display an... 

Electron microscopy The use of pyrazinedicarboxylate-type precursors was found to generate the largest metal particles with a maximum size of 20 m, whereas the catalysts prepared from acetate precursors are so small that they are not detected by backscattered electron microscopy. EDX analysis of the (pzdc.PdBi/C) catalyst demonstrated the bimetallic nature of the metal particles. The SEM-EDX spectra of the used monometallic Ac.Pd/C catalyst tested in the presence of added dissolved bismuth, according to the procedure described elsewhere [8], gave evidence for bismuth deposition on the support and on Pd particles. 

Bismuth deposition onto copper oxides, 2SS 2S7f 2S ... 

Bismuth content in the earth s crust is about 2T0 . Bismuth deposits are few and far-between, bismuth recovering from the bismuth bearing ores being very complicated multistage process. 

Kinetic separation of metals from each other is less common. A notable exception is the electrogravimetric determination of copper/bismuth mixtures. This relies on bismuth deposition (pH 5.2-6.0, 0.30 V), being... 

Rrdlicka A, Bobrowski A, Kowal A (2006) Effects of electroplating variables on the voltammetric properties of bismuth deposits plated potentiostatically. Electroanalysis 18 1649-1657 ... 

S. Szabd, Innestigation of copper,silver and bismuth deposition on palladium in perchloric acid media, 3. Electroanal. Chem., 77 (1977) 193-203. 

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. 

Early catalysts for acrolein synthesis were based on cuprous oxide and other heavy metal oxides deposited on inert siHca or alumina supports (39). Later, catalysts more selective for the oxidation of propylene to acrolein and acrolein to acryHc acid were prepared from bismuth, cobalt, kon, nickel, tin salts, and molybdic, molybdic phosphoric, and molybdic siHcic acids. Preferred second-stage catalysts generally are complex oxides containing molybdenum and vanadium. Other components, such as tungsten, copper, tellurium, and arsenic oxides, have been incorporated to increase low temperature activity and productivity (39,45,46). 

Alaska, Washington, and Nevada. Ores of the Southeast Missouri lead belt and extensive deposits such as in Silesia and Morocco are of the replacement type. These deposits formed when an aqueous solution of the minerals, under the influence of changing temperature and pressure, deposited the sulfides in susceptible sedimentary rock, usually limestone and dolomites. These ore bodies usually contain galena, sphalerite, and pyrite minerals, but seldom contain gold, silver, copper, antimony, or bismuth. 

Metals less noble than copper, such as iron, nickel, and lead, dissolve from the anode. The lead precipitates as lead sulfate in the slimes. Other impurities such as arsenic, antimony, and bismuth remain partiy as insoluble compounds in the slimes and partiy as soluble complexes in the electrolyte. Precious metals, such as gold and silver, remain as metals in the anode slimes. The bulk of the slimes consist of particles of copper falling from the anode, and insoluble sulfides, selenides, or teUurides. These slimes are processed further for the recovery of the various constituents. Metals less noble than copper do not deposit but accumulate in solution. This requires periodic purification of the electrolyte to remove nickel sulfate, arsenic, and other impurities. 

Solvent for Electrolytic Reactions. Dimethyl sulfoxide has been widely used as a solvent for polarographic studies and a more negative cathode potential can be used in it than in water. In DMSO, cations can be successfully reduced to metals that react with water. Thus, the following metals have been electrodeposited from their salts in DMSO cerium, actinides, iron, nickel, cobalt, and manganese as amorphous deposits zinc, cadmium, tin, and bismuth as crystalline deposits and chromium, silver, lead, copper, and titanium (96—103). Generally, no metal less noble than zinc can be deposited from DMSO. 

In Moroccan deposits, cobalt occurs with nickel in the forms of smaltite, skuttemdite, and safflorite. In Canadian deposits, cobalt occurs with silver and bismuth. Smaltite, cobaltite, erythrite, safflorite, linnaeite, and skuttemdite have been identified as occurring in these deposits. AustraUan deposits are associated with nickel, copper, manganese, silver, bismuth, chromium, and tungsten. In these reserves, cobalt occurs as sulfides, arsenides, and oxides. 

This approach is an alternative to quantitative metallography and in the hands of a master gives even more accurate results than the rival method. A more recent development (Chen and Spaepen 1991) is the analysis of the isothermal curve when a material which may be properly amorphous or else nanocrystalline (e.g., a bismuth film vapour-deposited at low temperature) is annealed. The form of the isotherm allows one to distinguish nucleation and growth of a crystalline phase, from the growth of a preexisting nanocrystalline structure. 

It will be recalled that is 100% abundant and is the heaviest stable nuclide of any element (p. 550), but it is essential to use very high purity Bi to prevent unwanted nuclear side-reactions which would contaminate the product Po in particular Sc, Ag, As, Sb and Te must be <0.1 ppm and Fe <10ppm. Polonium can be obtained directly in milligram amounts by fractional vacuum distillation from the metallic bismuth. Alternatively, it can be deposited spontaneously by electrochemical replacement onto the surface of a less electropositive metal... 

If no depolariser is added to an acidic chloride solution, corrosion of the anode occurs and the dissolved platinum is deposited on the cathode, leading to erroneous results and to destruction of the anode. A number of metals (for example, zinc and bismuth) should not be deposited on a platinum surface. 

The solution should be free from the following, which either interfere or lead to an unsatisfactory deposit silver, mercury, bismuth, selenium, tellurium, arsenic, antimony, tin, molybdenum, gold and the platinum metals, thiocyanate, chloride, oxidising agents such as oxides of nitrogen, or excessive amounts of iron(III), nitrate or nitric acid. Chloride ion is avoided because Cu( I) is stabilised as a chloro-complex and remains in solution to be re-oxidised at the anode unless hydrazinium chloride is added as depolariser. 

In a similar determination described by Lingane and Jones,11 an alloy containing copper, bismuth, lead, and tin is dissolved in hydrochloric acid as described above, and then 100 mL of sodium tartrate solution (0.1 M) is added, followed by sufficient sodium hydroxide solution (5M) to adjust the pH to 5.0. After the addition of hydrazinium chloride (4 g), the solution is warmed to 70 °C and then electrolysed. Copper is deposited at —0.3 volt, and then sequentially, bismuth at —0.4 volt, and lead at —0.6 volt all cathode potentials quoted are vs the S.C.E. After deposition of the lead, the solution is acidified with hydrochloric acid and the tin then deposited at a cathode potential of — 0.65 volt vs the S.C.E. 

Antimony and Bismuth. In attempting to dissolve alloys of these metals in hot 72% perchloric ac, a coating was formed which was very sensitive and expl. The chem nature of the deposits was not ascertained (Ref 9)... 

Another ferroelectric material is bismuth titanate, (Bi4Ti30i2), which is deposited from triphenyl bismuth, Bi(C5H5)3, and titanium isopropoxide at low pressure (5 Torr) and at temperatures of 600-800°C.[43]... 

Salmonella typhi, in the presence of glucose, reduces bismuth sulphite to bismuth sulphide, a black compound the organism can produce hydrogen sulphide from sulphur-containing amino acids in the medium and this will react with ferrous ions to give a black deposit of ferrous sulphide (Table 1.2). 

Cathodic deposition of bismuth(in) telluride films has been reported [224] also on copper and nickel foils, from aqueous nitric acid solutions of bismuth oxide and tellurium oxide in molar ratios of Bi Te = 3 3 and 4 3, at 298 K. The... 

Michel S, DUiberto S, Boulanger C, Stein N, Lecuire JM (2005) Galvanostatic and potentio-static deposition of bismuth teUuride films from nitric acid solution effect of chemical and electrochemical parameters. J Cryst Growth 277 274-283... 

Tittes K, Plieth W (2007) Electrochemical deposition of ternary and binary systems from an alkaline electrolyte—a demanding way for manufacturing p-doped bismuth and antimony teUurides for the use in thermoelectric elements. J Solid State Electrochem 11 155-164... 

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