Lead Dioxide - Production

Production

Lead dioxide is produced commercially by several methods, which include oxidation of Pb3O4 in alkaline slurry in a chlorine atmosphere, reaction of lead(II) acetate with calcium chloride, or reacting Pb3O4 with dilute nitric acid:

Pb3O4 + 4 HNO3 → PbO2 + 2 Pb(NO3)2 + 2 H2O

An alternative synthesis method is electrochemical: lead dioxide forms on pure lead, in dilute sulfuric acid, when polarized anodically at electrode potential about +1.5 V at room temperature. This procedure is used for large-scale industrial production of PbO2 anodes. Lead and copper electrodes are immersed in sulfuric acid flowing at a rate of 5–10 L/min. The electrodeposition is carried out galvanostatically, by applying a current of about 100 A/m2 for about 30 minutes. The drawback of the lead electrode is its softness, especially compared to the hard and brittle PbO2 which has a Mohs hardness of 5.5. This mismatch in mechanical properties results in peeling of the coating. Therefore, an alternative method is to use harder substrates, such as titanium, niobium, tantalum or graphite and electrodeposit PbO2 on them from lead(II) nitrate in static or flowing sulfuric acid. The substrate is usually sand-blasted before the deposition to remove surface oxide and contamination and to increase the surface roughness and adhesion of the coating.

Read more about this topic:  Lead Dioxide

Famous quotes containing the word production:

    “An art whose limits depend on a moving image, mass audience, and industrial production is bound to differ from an art whose limits depend on language, a limited audience, and individual creation. In short, the filmed novel, in spite of certain resemblances, will inevitably become a different artistic entity from the novel on which it is based.”
    —George Bluestone, U.S. educator, critic. “The Limits of the Novel and the Limits of the Film,” Novels Into Film, Johns Hopkins Press (1957)

    “Every production of an artist should be the expression of an adventure of his soul.”
    —W. Somerset Maugham (1874–1965)

    “I really know nothing more criminal, more mean, and more ridiculous than lying. It is the production either of malice, cowardice, or vanity; and generally misses of its aim in every one of these views; for lies are always detected, sooner or later.”
    —Philip Dormer Stanhope, 4th Earl Chesterfield (1694–1773)