Bromine extn. from salt solns. contg. bromide ions - where bromine is extracted by air and collected in satd. ammonium bromide soln., producing ammonium poly:bromide(s)

摘要

Stream of air is fed through a salt soln. (a) to remove bromide, which is then conc. in a cold conc. soln. (b) of ammonium bromide, thus obtaining a soln. (c) of ammonium polybromide, which has a low vapour pressure less than that of pure water contg. the same amt. of bromine, at 5-58 deg.C. Soln. (b) is pref. satd. with ammonium bromide; whereas soln. (c) pref. has a total bromine content exceeding 100 g/l. Soln. (c) is pref. neutralised with ammonia, and then the hot soln. is cooled for mfr. ammonium bromide crystals; alternatively, the hot neutralised soln. can be distilled to mfr. bromine. The winning of bromine from salt solns. or seawater involves its displacement by Cl2 and its extn. by air or steam. The Br2 is then absorbed in various solns. The conventional processes required large amts. of Cl2 and chemicals. The invention provides a process with much lower costs.