Overcoming the challenges of forward osmosis using electric field: A comprehensive review of recent advances

The application of an electric field to forward osmosis (FO) membranes enhances pure water flow by reducing membrane fouling and ion density. This electric field facilitates the electro-oxidation of pollutants, hydroxyl radical generation for pollutant degradation, or surface charging for pollutant rejection through electrostatic repulsion. Studies predominantly use electro-FO membranes as anodes to oxidize organic pollutants or repel cationic solutes. Electrically active materials like carbon nanotubes (CNT), carbon nanofibers (CNF), graphene nanosheets (GNS), graphene/polyaniline polyelectrolyte (GNS/PANI), and reduced graphene oxide/polyaniline (rGO/PANI) integrated into membranes eliminate various water contaminants and enhance antifouling properties. The electric field applied to FO membranes improves pure water permeation, contaminant removal, antifouling, and pollutant selectivity. Electro-FO membranes, when employed as anodes, exhibit significant advancements in water treatment. Electricity can also be applied directly to the feed solution, influencing the electrocoagulation of soluble compounds and particulate matter to prevent their electromigration and electro-deposition on the membrane. Additionally, the direct application of an electric field to the draw side of an FO unit aids in recovering fresh water from diluted draw agents.