Aqueous Aluminum Sulfate process

The aluminum trialkoxides are then hydrolyzed with dilute sulfuric acid in the Ethyl process (23)- This forms free alcohol and an aqueous aluminum sulfate solution which are separated by phase split. The aqueous aluminum sulfate is sold. Product alcohols are washed with caustic to remove traces of acid, dried, and fed to conventional distillation train. The product alcohols are sold by Ethyl under the trade name of EPAL alcohols. 

There are several processes available for the manufacture of cryoHte. The choice is mainly dictated by the cost and quaUty of the available sources of soda, alumina, and fluoriae. Starting materials iaclude sodium aluminate from Bayer s alumina process hydrogen fluoride from kiln gases or aqueous hydrofluoric acid sodium fluoride ammonium bifluoride, fluorosiUcic acid, fluoroboric acid, sodium fluosiUcate, and aluminum fluorosiUcate aluminum oxide, aluminum sulfate, aluminum chloride, alumina hydrate and sodium hydroxide, sodium carbonate, sodium chloride, and sodium aluminate. 

Precipitation also can be induced by additives, a process generally called salting out because salts with ions common to those whose precipitation is desired are often used for this purpose. For instance, ammonium chloride is recovered from spent Solvay liquors by addition of sodium chloride and the solubility of BaCl2 can be reduced from 32% to 0.1% by addition of 32% of CaCl2. Other kinds of precipitants also are used, for instance, alcohol to precipitate aluminum sulfate from aqueous solutions. 

Several other processes for producing alumina based on ores other than bauxite have been announced. One process uses alunite, a hydrous sulfate of aluminum and potassium. It is claimed to be capable of producing 99% pure alumina from alunite containing only 10 to 15% alumina, compared with bauxite that assays 50% alumina. The alunite is crushed, dehydroxy-lated by heating to 750°C, ground, and treated with aqueous ammonia. Filtration removes the alumina hydrate, and potassium and aluminum sulfates are recovered from the filtrate (to be used as fertilizer constituents). The alumina hydrate is treated with sulfur dioxide gas, and the resulting aluminum sulfate is converted to alumina by heating in a kiln. 

The aqueous beryllium sulfate is separated from the solids by counter-current decantation thickener operations. A beryllium concentrate is produced by a counter-current solvent extraction process (Maddox and Foos 1966). This concentrate is stripped of its beryllium content with aqueous ammonium carbonate. By heating to 70 °C, aluminum and iron are precipitated and then removed by filtration. Precipitation of beryllium basic carbonate occurs when the solution is heated to 95 °C. The carbonate is filtered, deionized water is added, and heating to 165 °C yields a beryllium hydroxide product which is the common input to beryllium-copper alloy, beryllium oxide ceramics, or pure beryllium metal (Table 2.1-2). 

Section 23.4 Electrometallurgy is tire use of electrolytic methods to prepare or purify a metallic element. Sodium is prepared by electrolysis of molten NaCl in a Downs cell. Aluminum is obtained in the Hall process by electrolysis of AI2O3 in molten cryolite (NagAlFg). Copper is purified by electrolysis of aqueous copper sulfate solution using anodes composed of impure copper. 

Aluminum sulfate cannot be used for gel preparation directly from solutions because of its very low solubility in alcohol or in aqueous solutions of any pH. However, optically clear gels can be obtained from both aluminum chloride and nitrate with TEOS aluminum chloride is less suitable for sol-gel processes than aluminum nitrate. The number of bonded A1 atoms was much lower in the chloride-containing gels than in the nitrate-containing gels. The very low A1 incorporation resulted from the acid medium. The gel structure obtained from aluminum chloride is dominated by the silica fractal network strongly deformed by the nonbonded A1 content. In addition, in the case of aluminum chloride, a washing step is needed to remove the anions. 

The RH in most indoor environments is usually not above 70 percent and, thus, the CRH of most common metals is seldom exceeded. The time-of-wetness will be quite small. The corrosion rate is likely to be comparable to the outdoor rate (at similar contaminant levels) when the surfaces are dry. Such rates are insignificant compared to the wet rates for most metals (18). In many cases, the anions associated with deposited substances may play the dominant role in surface processes (24). The concentrations of sulfate, nitrate, and chloride, which accumulate on these surfaces, are likely to increase continuously. After 10 years exposure, total anion concentrations of five to ten /ng/cm can be expected in urban environments. These anions, especially chloride, are well known to dramatically affect the corrosion rates of many metals in aqueous solutions. This acceleration is often a result of solubilization of the surface metal oxide through complexation of the metal by the anions. Chloride, in particular, can dramatically lower the RH above which a moisture film is present on the surface, since chloride salts often have low CRHs (e.g., zinc chloride - < 10 percent calcium chloride - 30 percent and aluminum chloride - 40 percent). The combination of the low CRHs of chloride salts and the well documented ability of dissolved chloride to break down metal oxide passivation set chloride apart from the other common anions in ability to corrode indoor metal surfaces. Some nitrate salts also have moderately low CRHs (e.g., zinc nitrate -38 percent calcium nitrate - 49 percent aluminum nitrate - 60 percent). 

A double metal oxide sulfate solid superacid (alumina-zirconia/ persulfate, SA-SZ) can be prepared by treatment of a mixture of aluminum hydroxide and zirconium(IV) hydroxide with an aqueous solution of ammonium persulfate, followed by calcination at 650°C. This catalyst can be efficiently utilized in the benzoylation of arenes with benzoyl and parfl-nitrobenzoyl chloride (Table 4.22), giving BPs in interesting yields. Even if 1 g of catalyst is needed for 40 mmol of chloride, the process seems to be quite useful because the catalyst can be readily regenerated by heating after washing with acetone and diethyl ether and reused four times. 

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