Removal of Dissolved Inorganic Impurities

Untreated water containing much dissolved hydrogen carbonate forms, upon heating, a precipitate consisting mainly of calcium carbonate (carbonate hardness, boiler scale)  

Hardeners, especially calcium and magnesium hydrogen carbonates rendered untroublesome by addition of  

The carbonate hardness can be removed by adding acid, whereupon the more soluble calcium sulfate is formed  

The resulting carbon dioxide has to be expelled, as carbon dioxide-containing water is corrosive. The hydrogen carbonate can be removed by the addition of calcium hydroxide  

Removal of iron(II) and manganese(II) ions by oxidation of the bivalent ions with air, or if necessary, with chlorine and separation of the oxide hydrates formed. Dissolved carbon dioxide also expelled during air oxidation 

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Removal of dissolved inorganic impurities from methanol Is of Interest from the point of view of utilization of methanol as an alternative to conventional fuels. Reports show that the corrosion rate of metal alloys used for turbines and fuel transportation is greater in methanol than in water in the presence of traces of chlorine and sodium ions ( , 10). Further, ion complexes in trace quantities have been observed in methanol and there is concern that they could alter the reaction kinetics for processes which use methanol as a feedstock or reaction medium (11). Methanol that Is used as a feedstock In the production of single cell protein could be sterilized as well as purified of heavy metals by reverse osmosis which can be integrated in the design of these processes. 

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