Alums preparation

The dichromate ion oxidises iron(II) to iron(III), sulphite to sulphate ion, iodide ion to iodine and arsenic(III) to arsenic(V) (arsenate). Reduction of dichromate by sulphite can be used to prepare chrome alum, since, if sulphur dioxide is passed into potassium dichromate acidified with sulphuric acid, potassium and chromium(III) ions formed are in the correct ratio to form the alum, which appears on crystallisation ... 

However the Mn (aq) ion can be stabilised by using acid solutions or by complex formation it can be prepared by electrolytic oxidation of manganese(II) solutions. The alum CaMn(S04)2.12H2O contains... 

When a solution of, say, 1 g. of hydroquinone in 4 ml. of rectified spirit is poured into a solution of 1 g. of quinone in 30 ml. of water, qulnhydrone C,HA.C,H (0H)3, a complex of equimolecular amounts of the two components, is formed as dark green crystals having a gfistening metallic lustre, m.p. 172°. In solution, it is largely dissociated into quinone and hydroquinone. Quinhydrone is more conveniently prepared by the partial oxidation of hydroquinone with a solution of iron alum. 

The slurry is pumped iato another stock chest, where wax ia emulsion form, usually about 0.5—1.0% wax-to-fiber weight, and 1—3% PF resia are added. PF resia is also added on the basis of resia soHds-to-dry fiber. Thea a small amouat of alum is added, which changes the pH (acidity) of the slurry, causiag the resia to precipitate from solutioa and deposit on the fibers. Resia is required ia greater quantity than ia the Masonite process because only light bonding occurs between fibers prepared ia a refiner. The fiber slurry is thea pumped to the headbox of a Fourdrioier mat former, and from this poiat the process is similar to the Masonite process. 

This PAG contains 1—2% sulfate as soluble calcium sulfate. Sulfate has been found to make PAG products unstable precipitate forms in less than one week at 50°G. Sulfate, however, has also been seen to increase PAG activity in water clarification and is thus intentionally added in one preparation (24). Precipitated calcium sulfate creates a sludge disposal problem. Typical Al content as AI2O2 of PAG products made from alum is 6 —8%. 

Other inorganic selenium compounds include sodium selenocyanate [4768-87-0], NaSeCN, which is prepared by melting together selenium and sodium cyanide selenocyanogen [27151 -67-3] (SeCN)2 sodium selenosulfate [25468-09-1], Na2SeS02, which is prepared by dissolving selenium in aqueous sodium sulfite (acidification decomposes this compound) and selenate alums, eg, Al2(Se0 2 I SeO [13530-59-1]. 

Alpha carbon atoms, 348 Alpha decay, 417, 443 Alpha particle, 417 scattering, 245 Aluminum boiling point, 365 compounds, 102 heat of vaporization, 365 hydration energy, 368 hydroxide, 371 ionization energies, 269, 374 metallic solid, 365 occurrence, 373 properties, 101 preparation, 238. 373 reducing agent, 367 Alums, 403 Americium... 

Note. Prepare the precipitating reagent by dissolving 5.0 g aluminium potassium sulphate (potash alum) in 90 mL warm water. Cool and add dropwise with stirring, while cooling in ice, a solution of 2.0 g sodium hydroxide in 5.0 mL water until the initially formed precipitate re-dissolves. After standing for 12 hours, filter, adjust the pH to 12.6, and dilute to 100 mL with water. 

In the early 1900s, a balanced mixture of diphtheria toxin and antitoxin was found to produce active immunity in both animals and humans. This preparation gained widespread acceptance and protected approximately 85% of recipients. Several years later, diphtheria toxoid was developed by treating the toxin with small amounts of formalin. This process caused the toxin to lose its toxic properties while maintaining its immunogenic properties. In the mid-1920s, the addition of an alum precipitate enhanced the immunogenic properties of the toxoid. 

Flocculating agents can be simple electrolytes that are capable of reducing the zeta potential of suspended charged particles. Examples include small concentrations (0.01-1%) of monovalent ions (e.g., sodium chloride, potassium chloride) and di- or trivalent ions (e.g., calcium salts, alums, sulfates, citrates or phosphates) [80-83], These salts are often used jointly in the formulations as pH buffers and flocculating agents. Controlled flocculation of suspensions can also be achieved by the addition of polymeric colloids or alteration of the pH of the preparation. 

Detailed examination of another madder preparation proved that the sample can be premordanted with alum. [ 19] After hydrolysis performed with hydrochloric acid and extraction with M-amyl alcohol, only four colourants are found alizarin, purpurin, and probably lucidin and ruberythric acid. Additionally, signals at m/z 525 and 539 are observed in the mass spectrum. Analysis of the preparation by inductively coupled plasma mass spectrometry (ICP MS) shows that aluminium and calcium are the main inorganic components of the sample. This is why it was suggested that the signal at m/z 539 can be attributed to the complex of aluminium with alizarin, and the second one, observed at m/z 525, to an aluminium-calcium cluster. 

AKDs are waxy, water-insoluble solids with melting points around 50 °C, and ASAs are viscous water-insoluble liquids at room temperature. It is necessary to prepare them as stabilised emulsions by dispersion in a cationic polymer (normally cationic starch). Small amounts of retention aid and surfactants may also be present. Particle size distributions are around 1 fim, and addition levels around 0.1% (of pure AKD or ASA) by weight of dry fibre. This is an order of magnitude lower than the amount of rosin used in rosin-alum sizing (1-2%). Emulsions of AKD are more hydrolytically stable than ASA, and the latter must be emulsified on-site and used within a few hours. 

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). 

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