Bismuth oxide test

A 33-year-old woman with atopic hand eczema and allergic rhinitis was given Noviform, an eye ointment containing bibrocathol (bismuth oxide and tetrabromo-cathechol), for periorbital dermatitis and noticed an exacerbation of her dermatitis (32). A patch test was positive for bismuth oxide. 

As rhodium is not the actual catalytic center and is very expensive, modifications have been done on both the catalyst and the starting materials. For example, one modification used O -AI2O3-supported platinum as a catalyst, and mixture of C2H6, NH3, and oxygen as the reactants. In other modification, the combination of manganese oxide and bismuth oxide was tested as a catalyst. ... 

This test for lead is interfered with by cerium, manganese, bismuth, cobalt, nickel, silver and thallium salts. Under the same conditions, these metal ions also give higher oxides capable of oxidizing benzidine to benzidine blue. If, however, the lead test is carried out in an alkaline extract (plumbite solution), only thallium offers interference. All the other metal ions are precipitated as hydrous metal oxides and so do not enter the alkaline extract. When only bismuth salts are present, it is sufiftcient, before the addition of bromine water, simply to heat with the alkali, BiO(OH) is formed which is not converted into the higher bismuth oxide by hypobromite. 

In another experiment [27] NF.PA circulated bismuth with a 50-gpm centrifugal pump for 100 hr at a mean temperature of 1500°F with a temperature differential of 500°F. An accumulation in the sump of a residue high in oxide content and dissolved elements reduced the flow and forced suspension of operation. This residue probably resulted from an impure inert atmosphere above the liquid metal. The container material selected was AISI type-347 stainless steel which had shown some promi.se in bismuth solubility tests at temperatures up to 1800°F. 

The presence of manganese can be detected by formation of the purple MnO upon oxidation using bismuth or periodate in acidic solution. A very sensitive test is the reaction of and formaldoxime hydrochloride in aqueous alkaline solution, which also leads to the production of a purple MnO ... 

The reason for the ultramicrochemical test was to establish whether the bismuth phosphate would carry the plutonium at the concentrations that would exist at the Hanford extraction plant. This test was necessary because it did not seem logical that tripositive bismuth should be so efficient in carrying tetrapositive plutonium. In subsequent months there was much skepticism on this point and the ultramicrochemists were forced to make repeated tests to prove this point. Thompson soon showed that Pu(Vl) was not carried by bismuth phosphate, thus establishing that an oxidation-reduction cycle would be feasible. All the various parts of the bismuth-phosphate oxidation-reduction procedure, bulk reduction via cross-over to a rare earth fluoride oxidation-reduction step and final isolation by precipitation of plutonium (IV) peroxide were tested at the Hanford concentrations of... 

Choosing divalent and trivalent cations and determining the composition is the most important in designing the multicomponent bismuth molybdate catalyst system. Catalytic activities of typical tri- and tetracomponent bismuth molybdate catalysts having multiphase structure were reported for the oxidation of propylene to form acrolein (35, 36, 40-43, 97, 98). A typical example of the activity test is shown in Fig. 6. Summarizing the results shown in Fig. 6 and reported previously (30, 43, 44), the following trends are generally found. 

Bismuth molybdate and other binary compositions (Fe—Mo, Sn—Sb and others) were tested by Germain and Perez [128] using a pulsed reactor. The authors demonstrate that a qualitative analogy may exist between ammonia and propene oxidation but if activities are compared, different sequences of catalytic efficiency arise. It must be noted, however, that these conclusions are based only on pulse experiments. These can be quite different from results in flow reactors, depending mainly on the nature of the steady state. 

These observations suggest a reaction scheme for bismuth molybdate catalysts where the allylic species is formed initially at a bismuth center and then reacts further at a molybdenum site to produce acrolein. Thus, once the allylic complex is formed, the MoO polyhedra are highly active and selective for acrolein formation. This hypothesis was tested by investigating the oxidation of bromoallyl (C3HjsBr) over molybdenum oxide 116). Since the C—Br bond in bromoallyl is much weaker than the C—H bond in propylene, the ease of formation of the allylic species should be significantly enhanced with bromoallyl compared with propylene. If the initial propylene activation occurs on bismuth, then the reaction of bromoallyl over molybdenum oxide should approach the activity and selectivity of propylene over bismuth molybdate. This was the observed result, and the authors concluded that the bismuth site was responsible for the formation of the allylic intermediate. 

As an example, platinum-bismuth catalysts with different atomic ratios have been prepared by the water-in-oil method and tested for the ethylene glycol electro-oxidation in alkaline medium [59],... 

While in Europe most limit tests use the method of standard additions, the United States Pharmacopoeia [84] requires that an aliquot of the test element equal to the set limit be added to the sample. If the response of the sample solution is less than the difference between the sample solution and sample plus aliquot (control) solution, it passes the test. Such a test may be used to limit sodium in other alkali salts. Atomic absorption spectrometry using the air/acetylene flame has been shown to be sufficient to test lead contamination in bismuth subcarbonate [114] and in zinc oxide and carbonate [115]. Miller [88] has reviewed such applications. 

Dry test (blowpipe test). When a bismuth compound is heated on charcoal with sodium carbonate in the blowpipe flame, a brittle bead of metal, surrounded by a yellow incrustation of the oxide, is obtained. 

Many other substances have been tested for use as additives for molybdenum disulphide films, including silver, tin, lead, lead oxide, bismuth trioxide and boron nitride , alumina, arsenic oxide, cadmium oxide, cuprous oxide, molybdic oxide. 

What, if any, relevance do such results have when predicting the influence of adsorbed bismuth on the CO of supported platinum nanoparticle catalysts In order to test the transferrability of results obtained on single crystals to practical fuel-cell anode catalysts, a series of experiments was performed [77] on a gas diffusion electrode of carbon-supported platinum (0.22 mg cm ) catalyst (Johnson Matthey). Figure 10 shows the results of polarization measurements for hydrogen oxidation at clean and bismuth-modified (0.65-ML) catalysts. In order to establish the CO tolerance of the electrodes, in addition to experiments involving pure H2,... 

The effect of the additional components has been illustrated by Sleight et al. [117], who prepared a series of Scheelite type (derived from the mineral CaW04) bismuth molybdate phases to which Pb was added to give a series of solid solutions of composition Pbi 3xBi2xx(Mo04). For every two bismuth ions in the structure a cation vacancy (())) was generated. When this series of catalysts was tested a relationship was observed between vacancy concentration and the rate of propene oxidation, as shown in Fig. 5.26. 

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