Seawater, lakes and wells brine as well as potassium manufacture liquor (with Bromine concentration up to 4-5 kg/m3) serve as main bromine sources. Bromine is isolated by passing Cl2 through with following sublimation by water vapour if Bromine concentration exceeds 1 kg/m3 or by air, if less, in packed columns made of ceramics, glass or titanium. Solutions with alkali reaction are previously acidified, usually by H2SO4 until pH 2.5-3.0. The heated reaction solution is supplied to the top of the column, water vapour - through the bottom and Cl2 somewhat higher. Vapour, which comes out of the column, is condensed. Then Bromine is separated from water and refined from Cl2 and organic contamination.
If Bromine less than 1 kg/m3 it is separated or by air. Solution previously treated by Cl2 is supplied to the top of the column and air - to the bottom. Bromine is captured by FeBr2 from the bromine-air mixture. FeBr3, the reaction product is reduced by iron turnings until FeBr2. In another method SO2 is added to the bromine-air mixture. In the presence of water HBr and H2SO4 appear. Bromine is isolated by Cl2. For Bromine absorption NaOH or Na2CO3 (3Na2CO3 + 3Br2 = 5NaBr + NaBrO3 + 3CO2) are used. Bromine is isolated by H2SO4. Residual Bromine is treated by Na2S2O3. |