Magnetic sponges (MSs) and magnetic threads with hydrophilic and hydrophobic characteristics that can perform remote-controlled oil/water separation in a confined space and anaerobic reactions were prepared. For large amounts of water or oil, trainlike hydrophilic or hydrophobic MSs composed of more than three sponge balls moved as a group and quickly absorbed the water or oil droplets in oil or water by magnetic manipulation from outside of the tube. For the removal of heavy oils below the water in three-liquid multiphase solutions, the hydrophobic MS balls were moved to the heavy oil below the water, absorbed some of the heavy oil, and returned to the light oil layer to deliver the heavy oil by means of an external magnetic field. The mixed oils floating on the water were easily removed by a suction pump once the heavy oil had been completely delivered to the light oil layer via the round-trip process. Furthermore, our approach was demonstrated for use in an anaerobic reaction system due to the strong magnetic property that transfers the reactants/products, the porous structure providing a reaction site, and the prewetting ability containing the reactants/products of the MSs and the oil layer prohibiting oxygen contact.
Keywords: anaerobic reaction; confined space; magnetic sponge and thread; oil/water separation.