Electrolytic membrane recovery of bromine from waste hydrogen bromide streams

A novel electrochemical process was developed for the recovery of bromine from waste gas-phase hydrogen bromide streams It uses a molten-salt-saturated membrane to electrolytically decompose hydrogen bromide into its molecular constituents, which are separated into a hydrogen-enriched waste stream and a pure bromine product stream. Single-cell studies were carried out in a configuration consisting of two cell housings (vitreous carbon), two gas-diffusion electrodes (reticulated vitreous carbon or graphite felt), and a molten salt [(Li0.575K0.133Cs0.292)Br] saturated membrane (zirconia). Single-cell results at 300 degrees C, based on process stream concentrations ranging from 25 to 75% hydrogen bromide at 50 to 300 mL/min, demonstrated current densities exceeding 1 A/cm(2) and removals as high as 95%. water and acetone (as a light organic contaminant) addition to the process Seed, as well as exposure to thermal cycling, showed no deleterious effects on cell performance. Preliminary economics indicate this to be a viable process.