Alums alumina

The compounds of greatest importance are aluminum oxide, the sulfate, and the soluble sulfate with potassium (alum). The oxide, alumina, occurs naturally as ruby, sapphire, corundum, and emery, and is used in glassmaking and refractories. Synthetic ruby and sapphire are used in lasers for producing coherent light. 

ALUMDJUMCOMPOUNDS - ALUMINIUMOXIDE(ALUMINA) - CALCINED, TABULAR, AND ALUMINATE CETffiNTS] (Vol 2) Potassium aluminum alum [7784-24-9]... 

This process is currentiy used by Vista Chemical, successor to Continental Oil Company s chemical business, and by Condea. In the Ethyl Corporation process dilute sulfuric acid is used in place of water in the hydrolysis step producing alum rather than alumina. 

Hydrolysis. Aluminum alkoxides are hydrolysed using either water or sulfuric acid, usually at around 100°C. In addition to the alcohol product, neutral hydrolysis gives high quaUty alumina (see Aluminum compounds) the sulfuric acid hydrolysis yields alum. The cmde alcohols are washed and then fractionated. 

Aluminum sulfate has largely replaced alums for the major appHcations as a sizing agent in the paper industry and as a coagulant to clarify municipal and industrial water suppHes. In terms of worldwide production, it ranks third behind alumina and aluminum hydroxide, with markets in excess of 3 x 10 t/yr (19). 

The large majority of activated alumina products are derived from activation of aluminum hydroxide, rehydrated alumina, or pseudoboehmite gel. Other commerical methods to produce specialty activated aluminas are roasting of aluminum chloride [7446-70-0], AIQ calcination of precursors such as ammonium alum [7784-25-0], AlH2NOgS2. Processing is tailored to optimize one or more of the product properties such as surface area, purity, pore size distribution, particle size, shape, or strength. 

The reaction is cataly2ed by all but the weakest acids. In the dehydration of ethanol over heterogeneous catalysts, such as alumina (342—346), ether is the main product below 260°C at higher temperatures both ether and ethylene are produced. Other catalysts used include siUca—alumina (347,348), copper sulfate, tin chloride, manganous chloride, aluminum chloride, chrome alum, and chromium sulfate (349,350). 

Alaunerde,/. alumina, alaunerdehaltig, a. aluminiferous. Alaun-erdesulfat, n. sulfate of alumina (aluminum sulfate), -erz, n. alunite. -fass, n. (L ol/ier) alum vat. -fels, m. alunite. -festig-keit,/. Paper) alum resistance, alaun-ftirmig, a. aluminiform. -gar, a. dressed with aluQi, alumed, tawed. 

Fig. 4. Synthesis of the alumina abrasives using the alum process. (Courtesy of Baikowski International Corp., Charlotte, NC.)...

In an undated letter to J. G. Gahn, which was probably written in 1774, Scheele stated that he had precipitated alum with lime water. "When I had the right proportion of the lime water to the acid in the alum, said he, I got a precipitate of alumina and gypsum (calcium sulfate) in the solution, . . and I found neither lime or gypsum in the clear solution, but pure water (18). Thus it is evident that Scheele was at that time unaware of the presence of potash in alum. 

When A. S. Marggraf tried to prepare alum from alumina and vitriolic acid, he found that unless he added fixed alkali he obtained no crystals (19). In 1777 Lavoisier clearly stated that potash is an essential constituent of alum (18, 20). In analyzing a water containing aluminum sulfate, which the younger Cassini had sent him from Italy, Lavoisier added some potash When he evaporated the solution, he obtained crystals of alum and realized that this was a verification of the results of Marggraf and of Macquer. 

In 1821 Arfwedson published a supplementary note to his lithium research (11), in which he stated that the salt which he had previously reported as lithium acid sulfate must be the normal sulfate and that the double sulfate he had at first taken for lithium alum was really potassium alum resulting from a trace of potassium in his alumina. 

Although the latter had previously overlooked the new earth because of its similarity to alumina, he found in 1798 that the hydroxide that precipitates when caustic potash is added to an acid solution of the beryl does not dissolve in an excess of the alkali. It also differs from alumina in other respects, for it forms no alum, it dissolves in ammonium carbonate, and its salts have a sweet taste. Vauquelin s paper read before the French Academy on le 26 pluviose an VI of the Revolutionary Calendar, or the fifteenth of February, 1798 (6, 23), proved that, except for a little chromium in the emerald, the two gems have the same composition and that they contain a new earth, a sample of which he presented to the Academy. At the suggestion of the editors of the Annales de Chimie et de Physique, he called the new earth glucina, meaning sweet. The specimen of beryl that Vauquelin analyzed was presented to him by... 

In 1747—48 Theodore Baron de Henouville (1715-1768) proved that borax is composed of sedative salt and soda (65). After A. S. Marggraf had investigated alumina ( the earth from alum ), Baron de Henouville in 1760 published a paper on the basis of alum. Although some of his observations were erroneous, he pointed out the close rela-... 

In an attempt to determine the composition of alum, A. S. Marggraf in 1754 added pure alkali to several pounds of it and precipitated what he called the earth of alum (Alaunerde). After he had thoroughly washed and dried this alumina, he tried in vain to regenerate the alum by adding sulfuric acid. 

Marggraf noticed that, when he dissolved the earth from alum in nitric acid, evaporated the solution, and calcined the residue, he merely regenerated the earth but obtained no Balduin s phosphorus (calcium nitrate). He realized, therefore, that the earth in alum must be different from that in chalk or limestone. He also demonstrated the presence of alumina in clay and in roofing slate (74). 

In addition to their energetic value, oil shales have also been used as sources for other materials, such as alumina, ammonium sulphate, phosphate, sodium carbonate, S, U, V, and Zn (Murray 1974). In the early 17th century, potassium aluminium sulphate was extracted from the Alum Shales in Sweden for use in the tanning and textile industry. It was only by the 19th century that hydrocarbons were being extracted from these Alum Shales while, in the 1960s, their content of U and V was being exploited (Dyni 2000). 

Evaporation of solutions of alumina in sulfuric acid yields crystals of A12(S04)3T6H20. If a group I sulfate is also present, the products are alums MA1(S04)2T2H20, in which aluminum exists as [Al(OH2)fi]3+. Analogous selenates but not tellurates have been prepared. Basic salts, e.g. Al2(OH)2(SO4)210H2O, and solids obtained from aluminum sulfate solutions above 100 °C also contain complex ions in which the coordination sphere of Al3+ is occupied by OH groups and/or water molecules rather than sulfate ions. Thermal decomposition of the hydrate A12(S04)3-16H20 yields practically anhydrous A12(S04)3 at 450 °C further decomposition to... 

Among the bottle-glasses, there are many which resist the action of wine, and which, nevertheless, are powerfully attacked by the nitric, hydrochloric, end sulphuric acids. Salts of lime, of iron, of alumina, and alum, are formed when sulphuric acid ie used. This acid produces in the interior of the bottles crystalline nipples or pustules, the base of which ultimately pierces the vessel these pustuleB arc sometimes of the size of a bean in all cases the silica set free assumes a jelly-like appearance. 

Tha orude solution of prussiate of potassa, and even the prussiate purified by a single crystallization, still contain, as has been stated, more or less carbonate of potassa, so that, besides the prussian blue, there is precipitated at the same time yellow oxide of iron, which deteriorates its tint. To obviate tills inconvenience, the carbonate of potassa is neutralized by sulphuric acid, which may he added cither to the solution of prussiate of potassa or to that of the protosnlphate of iron. In the manufacture of the common Berlin blues, the carbonate of potassa is neutralized by alum thoro results a precipitate of alumina, which mixes intimately with the prussian blue, and greatly augjnente... 

When chemically pure substances were taken, such as—1, Precipitated silica, in part fritted with the proper quantity of potassa 2, alumina, perfectly free from potassa, prepared by precipitation from alum 3, pure Ume instead of chalk—the mass melted at the lowest degree of heat in the kiln to a spotted enamel. 

Alumina and Sulphate of Lime.—The alumina obtained from two pounds of alum by precipitation aloug with sulphate of lime, by means of carbonate of lime in suspension, Is washed by decantation and added to one hundred gallons of cane juice. When tho temperature of tire simp has reached 150°, lime is added to neutralization and the juice is then filtered. 

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