|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.