Removal of Bromide from Water by Adsorption on Nanostructured δ-Bi2O3

Bromide, commonly found in produced water from shale gas extraction, has attracted much attention recently as use of bromide-contaminated source water could form brominated disinfection byproducts (DBPs) during drinking water treatment. The objectives of this study were to examine the feasibility of using delta-Bi2O3 to remove bromide from water, and identify the impact of water chemistry on bromide removal by this sorbent. Batch equilibrium tests indicate that delta-Bi2O3 can effectively remove bromide from water, having a maximum adsorption capacity of 147.1 mg/g at neutral pH. In the range of the solution pH 4.0-9.8 investigated, bromide removal increased steadily with decreasing solution pH. Chloride ions showed a major impact on bromide adsorption by delta-Bi2O3. The kinetics of bromide adsorption on delta-Bi2O3 were observed to be a fairly fast process following the pseudo-second order model. Based on the preliminary investigation of this study, it is speculated that the bromide uptake by delta-Bi2O3 could be a chemical adsorption process through formation of surface species similar to either Bi5O7Br or BiOBr. Findings of this study suggest that delta-Bi2O3 can be used to remove bromide from water solutions that have low concentration of chloride, having significant implications for treatment of bromide-contaminated waters.