Influence of carbonization of hot-pressed carbon nanotube electrodes on removal of NaCl from saltwater solution

Carbon nanotubes (CNTs) were hot-pressed as the electrodes of flow-through capacitor (FTC), which were used to remove NaCl from saltwater solution. The electrodes, obtained by hot-pressing CNTs with at least 20% phenolic resin (PR) binders, were investigated with battery-testing, nitrogen adsorption, scanning electron microscopy (SEM), atomic force microscope (AFM) and water contact angle. The results showed that the binders deteriorated the performance of the electrodes, and carbonization improved removal of NaCl from saltwater solution, with the efficiency up to 90%. After the electrodes being carbonized, many new pores were created on the surface; the specific surface area highly increased; the equivalent resistance greatly decreased; the hydrophilicity highly increased; the specific capacitance tremendously increased; thus, removal efficiency highly increased.