An Electroactive BiOBr/PVDF/CB Film Electrode for Electrochemical Extraction of Bromine Ions from Brines

An electroactive bismuth oxybromide/polyvinylidene difluoride/carbon black(BiOBr/PVDF/CB) composite film electrode was fabricated that had a bromide ion trap (Br^–-trap) effect obtained by prereleasing of Br^– under reduction potential. The Br^–-trap BiOBr/PVDF/CB film electrode was used for the selective extraction of Br^– from salt lake brine by electrochemically switched ion exchange (ESIX) technology. Moreover, an industrially scalable ESIX pilot system was designed and the effects of different process parameters were investigated. In the ESIX system, the obtained film electrode exhibited efficient adsorption quantity, and remarkable selectivity owing to its special ion trap effect. The extraction capacity of Br^– reached 67.10 mg g^–1 with the separation factors of 2.06 and 7.13 for Br^–/Cl^– and Br^–/NO₃^–, respectively, and the desorption efficiency of the film electrode remained at 95.4% after seven repeated cycles. It manifested that the pilot system with the Br^–-trap BiOBr/PVDF/CB film electrode is expected to provide a novel direction for practical industrial Br^– extraction.