Alum method

Submitted by Robert West and Robert P. Anderson Checked by Lewis I. KRiMENf and Therald Moeller  

The hot solution is cooled to 0°, and the. well-defined octahedra of cesium alum are collected on a sintered-glass funnel and washed with cold water. A small second crop of crystals is obtained when the filtrate is concentrated to about 450 ml. and cooled. The yield is about 110 g., or nearly 90% (for Yarutrask pollucite). 

Cesium alum crystallizes in colorless octahedra which melt at 117°. This compound is more insoluble than the other alkali-metal alums and is remarkable for its high 

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Museum Conservation of Wet Archaeological Wood. In 1951 the conservator at the National Museum of Denmark, Borje Brorson Christensen, published an article (2) about preservation of wooden objects found in peat bogs, in which he described the methods used to preserve that kind of material. By that time the drawbacks of the alum method, especially when glycerin was added, had began to show, and Christensen was working to find a suitable replacement for it. As PEG was not mentioned in his article. 

For specific uses, particularly for the preparation of ultrapure powders used for the synthesis of sapphire monocrystals, the Bayer process makes room for other methods, including ammonium alum method (dissolution of Bayer hydrargillite in excess sulphuric acid, neutralization in ammonia in NH4A1(S04)2.12H20 form, calcination at about 1,000°C and then milling) or the alcoholate method (based on an aluminum isopropylate). 

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 optimum conditions for roasting the clay and the optimum strength (30—60%) of the sulfuric acid used depend on the particular raw material. Finely ground bauxite or roasted clay is digested with sulfuric acid near the boiling point of the solution (100—120°C). The clay or bauxite-to-acid ratio is adjusted to produce either acidic or basic alum as desired and soHds are removed by sedimentation. If necessary, the solution can be treated to remove iron. However, few, if any, of the many methods claimed to be useful for iron removal have been used industrially (29). Instead, most alum producers prefer to use raw materials that are naturally low in iron and potassium. 

Water purification and recycling is now a major industry.The method of treatment depends on the source of the water, the use envisaged and the volume required. Luckily the human body is very tolerant to changes in the composition of drinking water, and in many communities this may contain 0.5 gl or more of dissolved solids (Table 14.7). Prior treatment may consist of coagulation (by addition of alum or chlorinated FeS04 to produce floes of Al(OH)3 or Fe(OH)3), filtration, softening (removal of... 

When we need to remove cells from fermentation broth, sedimentation is considered as a downstream processing method. Alum, lime, polyelectrolyte are commonly used. 

Method. Emulsion broken by mixing oily waste with alum and a chemical emulsion breaker, followed by gravity oil separation in a tank. 

Method Chemical precipitation of dissolved and complexed metals by reaction with lime and subsequent removal of the precipitated solids by gravity settling in a clarifier. Alum and polyelectrolyte are added for coagulation and flocculation. 

The uncorrected magnetic susceptibility of the cesium alum, determined by the Gouy method using the complex HgCo(NCS)4 as standard, is —0.12 c.g.s. units per gram this has been found to change to —0.03 c.g.s. units after 14 weeks.4... 

Rubidium alum obtained by either method above is decomposed by treatment with alkali solutions for removal of aluminum and sulfate. Aluminum is precipitated as aluminum hydroxide. Addition of barium hydroxide to the filtrate removes sulfate, precipitating barium sulfate. Evaporation of the solution crystallizes rubidium as hydroxide. 

Rubidium also may be recovered by the chlorostannate method. In this method the alkali metal carbonate solution obtained from the mixed alum is treated with carbon dioxide. Most potassium is precipitated as bicarbonate, KHCO3. Addition of hydrochloric acid converts the carbonates to chlorides. The chlorides are converted to chlorostannates by carefully adding stoichiometric quantities of stannic chloride at pH just below 7 ... 

Chemists of India prepared both chlorides of mercury as early as the twelfth century (244). A detailed description of the process was given in the thirteenth or fourteenth century (245). A mixture of common salt, brick dust, alum, Indian aloe, and mercury was heated for three days in a closed earthen pot. The Japanese and Chinese also prepared calomel by similar methods (244). 

After the Abb6 Lazaro Spallanzani (1729-1799) found an unworked deposit of native alum (alumte) in a grotto at Cape Miseno, near Naples, M H. Klaproth analyzed some specimens of it which John Hawkins collected tiiere. The Abbe Scipione Breislak described the extensive alunite deposits at Solfatara in 1792-93 and afterward became the director of an alum works tiiere. In his Travels in the Two Sicilies and Some Parts of the Apennines, Spallanzani wrote It is well known that for a long time alum and sal ammoniac have been extracted from this half-extinguished volcano (Solfatara). The methods employed were as follows In the process for the alum, certain square places were cleared out in die plain of Solfatara, in which it effloresced, and the efflorescences were swept together, and from them, by methods well known, the salt was collected purified. The sal ammoniac fumes were allowed to condense on pieces of tile near the apertures from which that salt issued. 

As previously stated, Wohler was unable to obtain metallic aluminum by Oersted s method. However, since the latter encouraged him to continue his attempts, he prepared some anhydrous aluminum chloride by Oersted s method, and devised a new plan for isolating the metal. After adding an excess of hot potassium carbonate solution to a boiling hot solution of alum, he washed and dried the precipitated aluminum hy-... 

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