A review of technologies for bromide and iodide removal from water

Natural activities and industrial emissions can lead to high bromide and iodide concentrations in surface water, and potentially pollute drinking water sources. During drinking water disinfection process, bromide and iodide can transform into brominated disinfection by-products (Br-DBPs) and iodinated disinfection by-products (I-DBPs), which are more toxic than chlorinated disinfection by-products (Cl-DBPs). Therefore, studying bromide and iodide removal from water is of great significance to the ecological environment, human health and resource recovery. In this work, we reviewed the techniques for bromide and iodide removal from water and unprecedently classified the techniques into four types: membrane techniques, adsorption techniques, electrochemical techniques and chemical oxidation techniques. It is worth mentioning that chemical oxidation is not covered in other reviews before. The halide removal performance, mechanism, applications, merit and demerit of each technique were discussed and compared. Finally, we proposed research priorities in the context of existing and future halide removal from water. Most of these methods have been studied in depth, but still have some problems and challenges. Electrolysis and chemical oxidation are mostly used in the field of bromine and iodine production, and less attention is paid to the remaining bromide and iodide in water. The research on electrolysis and chemical oxidation for halide removal is potential but lacking. It is hoped that this review will provide theoretical support and guidance for the development of new halide removal technologies and decision-making of environmental management.