Basic sulfates

Basic sulfates are intermediate compounds that contain lead oxide and lead sulfate and to some extent also water (Table 1). They are stable only in alkaline environment. 

Basic sulfates are important intermediates during the manufacturing process, since they determine the structure of the active material in the positive electrode, which again is decisive with respect to the 

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Sulfates. Indium metal and its oxides dissolve in warm sulfuric acid to give a solution of the trisulfate [13464-82-9], In2(S0 2- It is a white, crystalline, deUquescent soHd, readily soluble in water that forms double salts with alkaLi sulfates and some organic substituted ammonium bases. Concentration of the acidified trisulfate solution produces indium acid sulfate crystal [57344-73-7], In(HS0 2> other reaction conditions give basic sulfates. 

Lead forms a normal and an acid sulfate and several basic sulfates. Basic and normal lead sulfates ate fundamental components in the operation of lead-sulfuric acid storage batteries. Basic lead sulfates also ate used as pigments and heat stabilizers (qv) in vinyl and certain other plastics. 

Mercuric Sulfate. Mercuric s Af2iX.e.[7783-35-9] HgSO, is a colorless compound soluble ia acidic solutions, but decomposed by water to form the yellow water-iasoluble basic sulfate, HgSO 2HgO. Mercuric sulfate is prepared by reaction of a freshly prepared and washed wet filter cake of yellow mercuric oxide with sulfuric acid ia glass or glass-lined vessels. The product is used as a catalyst and with sodium chloride as an extractant of gold and silver from roasted pyrites. 

Carbonates. Basic zirconium carbonate [37356-18-6] is produced in a two-step process in which zirconium is precipitated as a basic sulfate from an oxychloride solution. The carbonate is formed by an exchange reaction between a water slurry of basic zirconium sulfate and sodium carbonate or ammonium carbonate at 80°C (203). The particulate product is easily filtered. Freshly precipitated zirconium hydroxide, dispersed in water under carbon dioxide in a pressure vessel at ca 200—300 kPa (2—3 atm), absorbs carbon dioxide to form the basic zirconium carbonate (204). Washed free of other anions, it can be dissolved in organic acids such as lactic, acetic, citric, oxaUc, and tartaric to form zirconium oxy salts of these acids. 

Basic zirconium sulfates are formed by hydrolysis of zirconium sulfate, which is broken up into fragments that undergo further hydrolysis to yield a series of basic sulfates with the generic formula Zr (OH)2 2 ( 4 )n-i (190). 

The most common basic sulfate is 5Zr02 ASO 535. [84583-91-5] which is precipitated in good yield when a zirconium oxychloride solution is heated with the stoichiometric amount in sulfate ion. It is used to prepare high purity oxides and ammonium zirconium carbonate. 

The gels precipitated as described above are not useful in ion-exchange systems because their fine size impedes fluid flow and allows particulate entrainment. Controlled larger-sized particles of zirconium phosphate are obtained by first producing the desired particle size zirconium hydrous oxide by sol—gel techniques or by controlled precipitation of zirconium basic sulfate. These active, very slightly soluble compounds are then slurried in phosphoric acid to produce zirconium bis (monohydrogen phosphate) and subsequently sodium zirconium hydrogen phosphate pentahydrate with the desired hydrauhc characteristics (213,214). 

Cadmium Sulfide. CdS [1306-23-6] is dimorphic and exists ia the sphalerite (cubic) and wurtzite (hexagonal) crystal stmctures (40). At very high pressures it may exist also as a rock-salt stmcture type. It is oxidized to the sulfate, basic sulfate, and eventually the oxide on heating ia air to 700°C, especially ia the preseace of moisture (9). 

There are four basic sulfates that can be identified by potentiometric titration using sodium carbonate (39,40) langite [1318-78-17, CuSO -3Cu(OH)2 H2 i brochantite [12068-81 -4] CuSO -3Cu(OH)2 antedite [12019-54-4] CuSO -2Cu(OH)2 and CuS0 -Cu0-2Cu(0H)2-xH20. The basic copper(II) sulfate that is available commercially is known as the tribasic copper sulfate [12068-81 ] CuS04-3Cu(0H)2, which occurs as the green monoclinic mineral brochantite. This material is essentially insoluble in water, but dissolves readily in cold dilute mineral acids, warm acetic acid, and ammonia solutions. 

Indium (III) sulfate (5H2O) [17069-79-3] M 607.9, d 3.44. Dissolve in strong H2SO4 and slowly evaporate at ca 50°. Wash crystals with glacial AcOH and then heat in a furnace at a temperature of 450-500° for 6h. Sol in H2O is 5%. The pentahydrate is converted to an anhydrous hygroscopic powder on heating at 500° for 6h but heating above this temperature over N2 yields the oxide sulfate. Evaporation of neutral aqueous solutions provides basic sulfates. [J Am Chem Soc 55 1943 1933, 58 2126 1936.]... 

However, as indicated in Fig. 15.17c, the system is complicated by the presence of several stable basic sulfates PbS04.nPb0 (n = 1, 2, 4), and these can react with gaseous PbS at lower metalmaking temperatures, e.g. ... 

Table 1. Basic sulfates that are formed as intermediate compounds when lead oxide is mixed with sulfuric acid.

In the lead-acid battery, sulfuric acid has to be considered as an additional component of the charge-discharge reactions. Its equilibrium constant influences the solubility of Pb2+ and so the potential of the positive and negative electrodes. Furthermore, basic sulfates exist as intermediate products in the pH range where Fig. 1 shows only PbO (cf. corresponding Pour-baix diagrams in Ref. [5], p. 37, or in Ref. [11] the latter is cited in Ref. [8]). Table 2 shows the various compounds. 

Although the phase which appears to be very stable for plutonium has not been observed in other An02 S03 H20 systems, phases of identical composition have been observed for Zr, Hf and Ce. The crystal structure of the zirconium compound Zr2(0H)2-(SOO 3 (H20) i,, is well known 05). One very interesting feature of the M02 S03 H20 systems for Zr, Hf and Co is that there are a large number of phases which have been observed. Some of these correspond to phases which are known for Th, U and Np. For zirconium, a series of basic sulfates is known to include Zr2(0H)2-(SOi,) 3 (H20)i, and two modifications of Zr(0H)2S0i, as the major constituents (5). Other basic sulfates such as Zr(OH)2S0if,H20,... 

The conditions under which the basic sulfates of tetraval-ent, Zr, Hf and Ce form provide analogies on which to base speculation about the hydrothermal hydrolysis of tetravalent plutonium. In the zirconium system at 100°C, the only basic sulfate observed is Zr2 (0H)2 (SOO3 ( 0), i.e., the zirconium analog of... 

Mercury(ll) sulfate hydrolyzes in water forming a basic sulfate HgS04 2Hg0. It forms double sulfates with alkali metal sulfates, such as K2S04-3HgS04-2H20. 

Heavy white crystals orthorhombic structure density 4.15 g/cm decomposes at 378°C to Sn02 and SO2 soluble in water, reacting to form a basic sulfate that precipitates soluble in dilute sulfuric acid. 

The crude tetrachloride mixture of zirconium and hafnium is dissolved in ammonium thiocyanate solution. The solution is extracted with methyl isobutyl ketone (MIBK). MIBK is passed countercurrent to aqueous mixture of tetrachloride in the extraction column. Halhium is preferentially extracted into MIBK leaving zirconium in the aqueous phase. Simultaneously, zirconium tetrachloride oxidizes to zirconyl chloride, ZrOCb. When sulfuric acid is added to aqueous solution of zirconyl chloride, the chloride precipitates as a basic zirconium sulfate. On treatment with ammonia solution the basic sulfate is converted into zirconium hydroxide, Zr(OH)4. Zirconium hydroxide is washed, dried, and calcined to form zirconium oxide, Zr02. 

One important aspect of such coating processes is the generality of the procedure. It would appear that specific surface characteristics of the preformed particles are not necessarily essential for the successful deposition of the new layer. For example, yttrium basic carbonate coatings were produced on zirconium basic sulfate... 

Aqueous 1 M chromium trioxide (12) does not react with metallic polonium, but with polonium(IV) hydroxide or tetrachloride yields an orange-yellow solid, thought to be Po(Cr04)2. This is insoluble in an excess of the reagent and is easily hydrolyzed by water or wet acetone to a dark brown basic chromate with a composition close to 2Po02 Cr()3 (cf., the basic sulfate and selenate). On long standing in an excess of aqueous chromium trioxide, oxidation to polonium(VI) may occur (Section VI,A). 

The white basic selenate, 2Po02Se03, is obtained by treating polonium V) hydroxide or chloride with selenic acid (0.015 iV-5.0 N) the salt is yellow above 250°C and is stable to over 400°C. It is rather less soluble than the basic sulfate, but the solubility increases a hundredfold in passing from 0.05 N to 5 N selenic acid (10), indicating complex ion formation. 

The white basic sulfate, 2Po02-S03, results when polonium(IV) hydroxide or chloride is treated with 0.02 N-0.25 N sulfuric acid. Like the selenate, it is yellow above 250°C and decomposes to the dioxide at 550°C. Solubility studies indicate that it is metastable in contact with 0.1 N-0.5 N sulfuric acid (10). 

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