The Alums

Piccini was obsessed with studying the limiting form of the elements as placed in the periodic table. With this in mind, he took up a new field of research, the synthesis of double sulfates (or alums), a work that enormously stimulated his creativity and enthusiasm [58]. In rapid succession, he prepared the alums of vanadium [59], titanium [60, 61], rhodium [62], manganese [63], iridium, and, finally, of thallium [64] with ammonium and then with the following alkaline metals cesium, mbidium, and potassium. Piccini ably used his method of synthesizing the rhodium sulfates virtually to quantitatively separate rhodium from iridium in solution. Through successive fractional crystallizations, Piccini obtained the alums of rhodium and cesium free of iridium, and through electrolysis of the alums he was able to obtain pure rhodium. 

Synthesis of the double sulfates of thaUium with ammonium, potassium and rubidium had an entirely different outcome. These alums [65] were of little interest 

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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... 

The pulp and paper industry and potable and wastewater treatment industry are the principal markets for aluminum sulfate. Over half of the U.S. aluminum sulfate produced is employed by the pulp and paper industry. About 37% is used to precipitate and fix rosin size on paper fibers, set dyes, and control slurry pH. Another 16% is utilized to clarify process waters. The alum sold for these purposes is usually Hquid alum. It is frequendy acidic as a result of a slight excess of H2SO4. Aluminum sulfate consumption by the pulp and paper industry is projected to remain constant or decline slightly in the near term because of more efficient use of the alum and an increased use of alkaline sizing processes (13). 

Water and Waste Water Treatment. PAG products are used in water treatment for removal of suspended soHds (turbidity) and other contaminants such as natural organic matter from surface waters. Microorganisms and colloidal particles of silt and clay are stabilized by surface electrostatic charges preventing the particles from coalescing. Historically, alum (aluminum sulfate hydrate) was used to neutralize these charges by surface adsorption of Al cations formed upon hydrolysis of the alum. Since 1983 PAG has been sold as an alum replacement in the treatment of natural water for U.S. municipal and industrial use. 

Most of the floeculation agent is removed with the floe, nevertheless, some question the safety of using alum due to the toxicity of the aluminum in it. There is little to no seientific evidence to back this up. Virtually all municipal plants in the US dose the water with alum. In bulk water treatment, the alum dose can be varied untU the idea dose is found. The needed dose varies with the pH of the water and the size of the particles. Increase turbidity makes the floes easier to produce not harder, due to the increased number of eollisions between partieles. 

Bulk alum can be stored in mild steel or concrete bins with dust collector vents located in, above, or adjacent to the equipment room. Recommended storage capacity is about 30 days. Dry alum in bulk form can be transferred or metered by means of screw conveyors, pneumatic conveyors, or bucket elevators made of mild steel. Pneumatic conveyor elbows should have a reinforced backing as the alum can contain abrasive impurities. 

FRP, plastics (polyvinyl chloride, polyethylene, polypropylene, and other similar materials), and rubber are general use and are recommended for alum solutions. Care must be taken to provide adequate support for these piping systems, with close attention given to spans between supports so that objectionable deflection will not be experienced. The alum solution should be injected into a zone of rapid mixing or turbulent flow. 

When solution must be pumped, consideration should be given to use of holding tanks between the dry feed system and feed pumps, and the solution water supply should be controlled to prevent excessive dilution. The dry feeders may be started and stopped by tank level probes. Variable-control metering pumps can then transfer the alum stock solution to the point of application without further dilution. Means should be provided for calibration of the chemical feeders. Volumetric feeders may be mounted on platform scales. Belt feeders should include a sample chute and box to catch samples for checking actual delivery with set delivery. Gravimetric feeders are usually furnished with totalizers only. Remote instrumentation is frequently used with gravimetric equipment, but seldom used with volumetric equipment. 

Bulk unloading facilities usually must be provided at the treatment plant. Rail cars are constructed for top unloading and therefore require an air supply system and flexible connectors to pneumatically displace the alum from the car. U.S. Department of Transportation regulations concerning chemical tank car unloading should be observed. Tank truck unloading is usually accomplished by gravity or by a truck mounted pump. 

Established practice in the treatment field has been to dilute liquid alum prior to application. However, recent studies have shown that feeding undiluted liquid alum results in better coagulation and settling. This is reportedly due to prevention of hydrolysis of the alum. 

Neutral or weak acid-salt solutions usually can be handled in lead plants, with the exception of those few heavy metals that may form lead alloys by substitution. The alums and sulfates generally have little action. 

In oxidation states lower than -t-4, only Ti forms a sulfate and this gives rise to the alums, MTi(S04)2-12H20 (M = Rb, Cs), containing the octahedral hexaaquotitanium(III) ion. 

The first of these types is most familiarly represented by the hexaaquo ion which is present in acidic aqueous solutions and, in the solid state, in the alum CsTi(S04)2.12H20. In fact few other neutral ligands besides water form a [TiLg] + complex. Urea is one of these few and [Ti(OCN2H4)g]l3, in which the urea ligands coordinate to the titanium via their oxygen atoms, is one of the compounds of titanium(III) most resistant to oxidation. 

Measurements of the kinetics of the individual nucleation and growth steps in the reactions of several hydrated sulphates have been referred to in Sect. 1.2 though, perhaps surprisingly, these data were not combined in a kinetic analysis for the overall reaction in studies of the alums [51,431, 586] or NiS04 7 H20 [50]. Indeed, Lyakhov and Boldyrev [81], in one of the few reviews of the field, maintain that the satisfactory topochemi-cal description of dehydrations is a problem which at present remains... 

Singer, Charles. The earliest chemical industry an essay in the historical relations of economics and technology illustrated from the alum trade., 1948. 

Mineral tanning was probably first practiced in ancient Mesopotamia and then spread to Egypt, the Middle East, and the Mediterranean Sea area (Levey 1958). Mineral-tanned leather is soft to handle, has a velvety texture, and is almost white, a color practically impossible to achieve by other tanning processes. It is, however, very sensitive to humidity and water under wet conditions the alum in the leather is hydrolyzed (decomposed by water), forming sulfuric acid, a very strong acid that attacks the leather and causes its rapid decay. Mineral-tanned leather that has been humid or wet for a more or less extended period of time loses some of its characteristic properties, such as softness, pliability, and strength, and becomes hard, horny, and brittle. 

Where the lowest values occur, the ground water is higher than the alum shale layer. 

Cesium is determined as the tetraphenylborate, total cobalt as the anthranilate, sulfate as barium sulfate, and cobalt(III) by addition of the alum to excess of potassium iodide solution followed by titration with thiosulfate- Anal. Calcd. -for CsCo(S04)2-12H20 Cs, 22.2 Co, 9.82 S04, 32.0. Found Cs, 22.2 Co, 9.83 S04, 32.3 Co(III), 9.80. 

Calculate how much 0.200 M Ba(N03)2 would be needed to totally precipitate all of the sulfate ion present in the alum solution. 

What was the percent sulfate ion in the alum based upon the experiment 2.715 g paper + barium sulfate - 1.675 g paper = 1.040 g BaS04... 

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