Alum, ammonium

The Verneuil Techni(jue. The VemeuH technique is also known as flame-fusion. A very pure feed powder is first made by chemical decomposition. For the growth of comndum, ammonium alum [7785-25-0] NH Al/(S0 2 12H20, is recrystallized from water containing added... 

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 word alum is derived from the Latin alumen, which was appHed to several astringent substances, most of which contained aluminum sulfate (20). Unfortunately, the term alum is now used for several different materials. Papermakers alum or simply alum refers to commercial aluminum sulfate. Common alum or ordinary alum usually refers to potash alum which can be written in the form K SO Al2(SO 24H20, or it can refer to ammonium alum, ammonium aluminum sulfate. The term is also appHed to a whole series of crystallised double sulfates [M(l)M (lII)(SO 2 12H20] having the same crystal stmcture as the common alums, in which sodium and other univalent metals may replace the potassium or ammonium, and other metals may replace the alurninum. Even the sulfate radical may be replaced, by selenate, for example. Some examples of alums are cesium alum [7784-17-OJ,... 

Azninon-. ammonium ammonia, -alaun, m. ammonia alum, ammonium alum, -chlorid, n. ammonium chloride. -eisenalaun, m. unmonium iron alum. -formiat, n. ammonium formate. 

S< dium Aluminato. . Ammonium Alum. . rola.uium Alum. . . Ammonia. . Ammonium (Ion). . Ammonium Chloride Ammonium Hydroxide Ammonium Sulfale... 

Ammonium alums undergo phase transitions at Tc 80 K. The phase transitions result in critical lattice fluctuations which are very slow close to Tc. The contribution to the relaxation frequency, shown by the dotted line in Fig. 6.7, was calculated using a model for direct spin-lattice relaxation processes due to interaction between the low-energy critical phonon modes and electronic spins. 

Aloton Also called Buchner. A process proposed for extracting aluminum from clay. Calcined clay is leached with ammonium hydrogen sulfate solution under pressure, and ammonium alum is crystallized from the liquor. Invented by M. Buchner in Hanover-Kleefeld in 1921 piloted in Germany in the 1920s and in Oregon in 1944. It was never commercialized, but provided the basis for the Nuvalon process which was. 

Ammonium acetates, 2 711-712 Ammonium alum calcination, 2 395 neutralization, 2 430 Ammonium benzoate, 3 634 Ammonium bicarbonate, 2 712-713 Ammonium bifluoride, 2 717-718 Ammonium bisulfate formation, 10 98 Ammonium bromide, 2 714... 

Synonyms ferric ammonium sulfate ammonium ferric sulfate iron alum ferric alum ferric ammonium alum... 

According to a recent patent [4], some unstable nitroso compounds may be stabilized by addition of such inert materials as ammonium bicarbonate, ammonium carbonate, magnesium acid phosphate, ammonium or sodium acid phosphate, calcium lactate, ammonium alum, and calcium silicate. 

Precipitate with aq. ammonia. Evaporate the soln. down to about 100 c.c., and filter the ot liquid so as to remove calcium sulphate. The cone. soln. is sat. with ammonium alum and allowed to stand for some time. The mixed crystals of potassium, rubidium, and oeesium alums and of lithium salt are dissolved in 100 c.c. of distilled water and recrystal-lized. The recrystallization is repeated until the crystals show no spectroscopic reaction for potassium or lithium. The yield naturally depends on the variety of lepidolite employed. 100. grms of an average sample gives about 10 grms. of crude crystals and about 3 grms. of the purified caesium and rubidium alums. For the purification of caesium and rubidium salts, see the chlorides. The mother-liquors are treated with an excess of barium carbonate, boiled, and filtered. The filtrate is acidified with hydrochloric acid, and evaporated to dryness. The residue is extracted with absolute alcohol in which lithium chloride is soluble, and the other alkali chlorides are sparingly soluble. 

HEAT WATER UNTIL IT IS SLIGHTLY MORE THAN LUKEWARM. STIR INTO IT POTASSIUM ALUM OR AMMONIUM ALUM UNTIL NO MORE DISSOLVES. POUR LIQUID OFF UNDISSOLVED ALUM. SET ASIDE TO COOL. 

Biiltemann 2 observed that vanadium ammonium alum separates out in blue crystals from a solution containing sulphuric acid, but from solutions containing a weak acid, or from neutral solutions, red crystals are obtained. (The chromium alums can also be prepared in differently coloured modifications.) The analytical data, melting-point, electrical conductivity, rate of efflorescence, and general behaviour of both kinds of crystals are identical, so that it is difficult to ascribe different constitutions to them. Meyer and Markowitz3 have shown that both forms separate out when the molecular proportion of sulphuric acid in the solution is less than that theoretically required, and attribute the red colour to the presence of traces of vanadous oxide, V203, or its hydroxide, V(OH)3. Vanadium rubidium and vanadium ciesium alums behave in the same way. A vanadium guanidine alum has also been prepared.4... 

Vanadous Pyrophosphate, V4(P2O7)2.30H2O, is obtained as a green, floceulent predpitate when vanadium ammonium alum is added to a solution of an alkaline pyrophosphate.3... 

Fig. 88. 27A1 Fourier transform pure nuclear quadrupole resonance spectra of potassium, ammonium, and mixed alums (428). The pair of high-frequency lines in the mixed sample (56 mol % potassium alum, 44 mol % ammonium alum) clearly indicates the existence of two distinct 27A1 lines.

The term alum, itself, refers to potassium alum, potassium aluminum sulfale, KA1(S04)2 12H O. Oilier common alums are ferric ammonium alum, NH4 Fe(S02)2 12HiO. and sodium chrome alum, NaCr(SOa)212ITO. 

Alum Ammonium alums are those alums, such as aluminum ammonium sulfate A12(NH4)2 (804)4 24H20, ferric ammonium sulfate Fe2(NH4)2< S04)4 - 24H2O, chromium ammonium sulfate Cr2(NH4)2 (S04)4 24H2O where ammonium sulfate is crystallized with the heavier metal sulfate. 

Chrome Ammonium Alum. See Ammonium -Chrome Alum in Vol 1, p AI56-L... 

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