Preparation of aqueous solutions of tetrafluoroboric acid

摘要

Prodn. of aq. soln. of tetrafluoroboric acid HBF4 from coloured aq. effluents contg. boron trifluoride hydrate BF3.xH2O comprises: (a) adding an aq. soln. of HF to the effluent in sufficient amt. to complete conversion of the BF3 to HBF4; (b) adding water and sufficient boric acid to neutralise any excess HF and to form soln. contg. 0.1-8 wt.% boric acid and greater than 49 wt.% HBF4; (c) contacting resulting soln. sufficient active carbon for sufficient time to lower organic carbon content of soln. to 30 ppm or less; and (d) sepg. active carbon from the decolourised soln. of HBF4.