Basic aluminum sulfate

Hydrates. Aluminum sulfate hydrates, Al2(SO H20, where n ranges from 0 to 27 have been reported (3—6). Relative decreasiag vapor pressure studies iadicate the presence of an octadecahydrate, hexadecahydrate, dodecahydrate, dihydrate, and the anhydrous salt, assumiag that basic aluminum sulfates are not formed duriag the dehydration (3). 

Dowa A flue-gas desulfurization process in which the sulfur dioxide is absorbed in a basic aluminum sulfate solution. The product solution is oxidized with air and reacted with limestone to produce gypsum. Developed by the Dowa Mining Company, Japan, in the early 1980s. In 1986 it was in use in nine plants in Japan and the United States. 

FORMATION OF BASIC ALUMINUM SULFATE BY PHASE TRANSFORMATION FROM CONDENSED HYDROXIDE GEL... 

Fig. 5.2.1 Transformation of the solid phase from amorphous aluminum hydroxide to spheroidal cubic particles of basic aluminum sulfate with aging time under the standard conditions [Al3 ] = 1.0 mol dm-3, IS042 ]/[A13+] = 2/3, [NaOHJ/[AI3+ = 1.8. temperature = 100°C. (From Ref. 1.)...

Fig. 5.2.2 Concentrations of Al3+ and S042 ions in the solution phase as a function of aging time in the standard system for the formation of the monodispersed basic aluminum sulfate particles. (From Ref. 1.)...

Fig. 5.2.5 SEM images of the basic aluminum sulfate particles of samples C-l, C-2, C-3. and C-4 systematically controlled in crystal habit at [S042-]/[AI3+] = 1/4 by variation of the overall fNaOH /[A13+] ratio as 1.5, 1.8, 2.4, and 2.7, respectively. The respective initial pH values are 3.0, 3.2, 3.7, and 6.9. (From Ref. 1.)...

Fig. 5.2.8 Size control of the basic aluminum sulfate particles by seeding in the standard system A-3 (B-3). The added amounts of the seeds in terms of the equivalent volume of the stock seed suspension in 24 cm3 of the standard hydroxide gel were (a) 0, (b) 1.2 X 10 2, (c) 2.4 X 10-1, and (d) 2.4 cm3. (From Ref. I.)...

Johansson G (1962c) On the crystal stracture of the basic aluminum selenate. Arkiv. Kemi 20 305-319 Johansson G, Lundgren G, Sillen LG, Soderquist R (1960) On the crystal stracture of a basic aluminum sulfate and the corresponding selenate. Acta Chem Scand 14 769-771 Jolivet J-P (1994) De la Solution a I Oxyde, 3rd ed, Masson, Paris... 

Enhancement of SO2 absorption by buffers was measured at 55°C in 0.3 M NaCl and 0.1 M CaCl2 for acetic, adipic, hydroxypropionic, sulfopropionic, and sulfosuccinic acids and for basic aluminum sulfate. These results were correlated by mass transfer with equilibrium reactions. Sulfopropionic acid and basic aluminum sulfate were less effective than expected. Relative economics were developed for these and seven additional buffers. 

In several of the studies of aqueous chemistry of aluminum that have been made since about 1950, polynuclear complexing mechanisms have been proposed to identify and describe the dissolved aluminum hydroxide complex species (3, JO, 11). The formulae proposed have generally been based on stoichiometric considerations and pH measurements assuming the polynuclear species were ionic, and that equilibrium was attained. The complex ions reported by Hsu and Bates (8) were single six-mem-bered rings Ale (OH) 12 or multiples of this unit. Johansson (JO) identified a structural unit containing 13 aluminum and 40 oxygen atoms with various numbers of protons in crystalline basic aluminum sulfate. Because this solid formed readily, the same structural unit of aluminum was proposed as a solute species. Most of the proposed formulae for polynuclear complexes, however, have not been derived from structural considerations. 

Synonyms Aluminum hydroxide silicate sulfate Basic aluminum sulfate Polyaluminum silicate sulfate... 

Basic aluminum chloride. See Polyaluminum chloride Aluminum chlorohydrate Basic aluminum sulfate. See Aluminum hydroxide sulfate... 

Satin white n. Filler made by precipitating together a mixture of calcium sulfate and aluminate. The ingredients used for its preparation are calcium hydroxide and basic aluminum sulfate. It is used chiefly in aqueous pigmented coatings for paper, and also as a base for lake pigments. 

The Dowa Dual Alkali Process uses a solution of basic aluminum sulfate to absorb SO2, air injection to oxidize sulfite to sulfate, and limestone to precipitate the resulting excess sulfate in the form of gypsum. 

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