Soda-alum process

Hard water is first pumped into the reaction tank and then aluminium sulphate is added to it as floculant. About 20-30 min is allowed to react and then the impurities are allowed to settle for about 30 min before filtration. Many floculants need alkali 

4Hp + 3Na,C03 + Al3(SOJ3 2A1(0H)3 + 3Na,SO + 3CO, + H,0 as an assistant floculant. If additional alkali is not added, the total alkalinity is reduced and part of aluminium sulphate, being water soluble may pass through the filter. As aluminium hydroxide and metals precipitate downwards, clear water arrives at the top and is decanted. 

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Chemical Processing. Activated carbon consumption in a variety of chemical processing appHcations is about 8% of the total (74). The activated carbon removes impurities to achieve high quaHty. For example, organic contaminants are removed from solution in the production of alum, soda ash, and potassium hydroxide (82). Other apphcations include the manufacture of dyestuffs, glycols, amines, organic acids, urea, hydrochloric acid, and phosphoric acid (83). 

The most common technique used to prepare the /i-type (i.e., or / ") alumina is to mechanically blend the component oxides or precursor compounds in powder form prior to a calcination or prereaction step at temperatures between 1000 and 1260°CT Commercially available aluminum oxide powders (0.3-0.5 pm average crystallite size) in the alpha (corundum) polymorph are typically usedT They are derived from three common sources decomposition of gibbsite [Al(OH)3], which is precipitated from soda liquors in the Bayer process preparation and decomposition of alum salts and preparation from aluminum chloride precursors NaaCOs is usually the source of Na20. Sources of Li20 have included Li2C03, LiNOs, and Li2C204- MgO is usually added as the commercially available oxide. 

Treatment with Mordant The mordant is essential for the dyeing process of the cloth or yarn in both the Turkish red and alizarin procedure. The mordant is necessary as fixative for the dye. Before 1750 alum was the main mordant used. After 1750 other mordants like basic aluminium sulphate and soda or chalk, aluminium acetate and later on aluminium sulphoacetate were used [20]. 

Kottula s Soaps.—K. departure from the ordinary system of Boap-raaking was introduced by Dr. Hottnla about twenty five years ago, and at the time attracted much attention. In conducting his process, Kottula adds to ordinary curd, mottled, yellow, or other soaps, made in the ordinary way, fatty matters, lime liquor, concentrated soda leys and alum, with the object of producing a cheaper neutral soap than he believes was hitherto produced. The fatty matters he employs are such as are commonly used by soap-makers. He first boils soda leys until they have acquired the strength of about 30 B., and then adds to them alum, in the proportion of about lbs. to each owt. of ley. He then prepares a lime liquor by adding to any requisite quantity of water as much lime as it will absorb or take up, and to this lime solution he adds sal ammoniac in the proportion of about half a pound to each owt. of the solution. Sometimes he omits the sal ammoniac. 

Lmubarton s Process consists in saponifying fatty matters by boiling them with an alkaline mixture composed of carbonate of soda, quicklime, common salt, and alum, the ingredients being mixed in the following proportions —Sub-carbonate of soda,... 

For surface water, treatment is aimed primarily at removal of turbidity (fine suspended matter) and perhaps softening the water. The typical treatment processes for removal of turbidity involve the addition of chemicals such as alum or ferric chloride. The chemicals are rapidly mixed into the water so that they react with alkalinity in the water, then slowly mixed (flocculation) to form a settleable precipitate. After sedimentation, the water passes through a sand filter and finally is disinfected wdth chlorine. If the water is to be softened as part of the treatment, lime, Ca(OH)2, and soda ash, Na COj, are used in place of alum or ferric chloride, and the water hardness (calcium and magnesium ions) is removed along with its turbidity. 

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