Studies on the ion-exchange equilibria carbonate-bicarbonate-chromate

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University of Dar es Salaam
The ion exchange equilibria carbonate bicarbonate-chromate is rather complex with CO32-, HCO-3, Cr2O2-7, HCrO4- and OH- ions all competing for the active sites in the resin. Equilibration of the strongly basic anion exchanger (chloride form) in sodium carbonate, sodium bicarbonate and potassium chromate solutions of different concentrations (0.05 2.00m) were carried out. The results allowed us to understand more clearly the nature and characteristic of absorption of the C032- HC03- and Cr042- ions into the ion exchange resin. The carbonate and bicarbonate were absorbed as CO32- HC03- and Na NaCO3- ions and also as the neutral molecules of carbonic acid (or hydrated carbon dioxide) and NaHC03. The chromate ions were absorbed by the resin as compared to carbonate and bicarbonate. A maximum of 3.24 mill equivalents of chromate was absorbed by a gram of resin while only 1.80 and 2.00 mill equivalents were the respective maximum amounts of carbonate and bicarbonate absorbed by a gram of the resin. In dilute solutions (concentration loss than o.1M) more carbonate was absorbed than bicarbonate from the respective equilibration solutions of similar strength. The results of the ion exchange equilibria studies were applied successfully to the separation and determination of chromium is chrome-iron ore. These results have yet to be used for separation of chromium in other allied industrial materials.
Ion exchange, Extraction (chemistry)
Othman, O. C.(1976) Studies on the ion-exchange equilibria carbonate-bicarbonate-chromate, Masters dissertations,University of Dar es Salaam. Available athttp://