Tribasic lead sulfate preparation

This lead compound forms prismatic crystals with a length of 1—4 pm and 0.2—08 pm in cross section. Its density is 6.5 g cm. It is poorly soluble in water, 0.0262 g L. 3BS is obtained when leady oxide is mixed with sulfuric acid solution (up to 8 wt % H2S04/Pb0) and constitutes the basic component of the battery paste when the latter is prepared at temperatures below 70 °C. Tribasic lead sulfate exerts an influence on the structure of the lead dioxide active mass and thus on some of the performance characteristics of the battery. 

Preparation of tribasic lead sulfate (3BS) pastes for positive plates. 

If tribasic lead sulfate and dibasic lead phthalate are coprecipitated in a more or less equal molar ratio, the resultant product has a core/shell stmeture, a sulfate core, and a phthalate shell.The infrared and NMR spectra of the surface of such coprecipitates is identical to that of pure dibasic lead phthalate. Such products can be substituted for dibasic lead phthalate (at somewhat lower cost) in many applications, usually at 5—7 phr. In lead stabilizers, the cost of the stabilizer is primarily a function of that of the acid used in its preparation. Such coprecipitates are produced as Halstab 30 and 60 and as addiStab SP6 and SP7. Although a copre-cipitate of sulfate and phthalate has low activity in ester hydrolysis, this does not extend to mere physical blends of the two, which show approximately the average catalytic power. 

Tetrabasic Lead Sulfate. Tetrabasic lead sulfate [12065-90-6] 4PbO PbSO, mol wt 1196.12, sp gr 8.15, is made by fusion of stoichiometric quantities of Htharge (PbO) and lead sulfate (PbSO heat of formation, Ai/ = — 1814 kJ/mol (—434.1 kcal/mol). Alternatively, tetrabasic lead sulfate may be prepared by boiling the components in aqueous suspensions. At about 70°C, tribasic hydrate reacts with lead oxide to form tetrabasic sulfate. At 80°C, this transformation is complete in - 20 hours. Tetrabasic lead sulfate is used in limited quantities in Europe as a PVC stabilizer. However, in the United States, lead-acid batteries have been developed by BeU Telephone Laboratories, which contain tetrabasic lead sulfate. Such batteries are used for emergency power at telephone switchboard stations and have an anticipated service life of over 50 years. 

---