Preparation of nanoporous composite carbon membrane for separation of rhodamine B dye

In this work, a clay-supported carbon membrane has been synthesized by carbonizing a blend of polyethylene glycol and resole-type phenol formaldehyde resin at 500 °C. The membrane thus prepared was characterized with respect to its pore structure and surface morphology. The hydraulic permeability was found to be considerably higher than that reported in literature. The thickness of the carbon membrane was determined to be 30 μm and the molecular weight cutoff experiments gave the average pore size of 1.8 nm. Experiments show that the real rejection of the dye is in the range of 90–100% and depends on the pressure and concentration of the dye. In the pH range of 6–8, the dye tends to dimerize and forms greater aggregations due to attractive electrostatic interaction, suggesting separation of the dye from its solution due to sieving by the membrane. In addition, since the membrane has charge opposite to that of the dye, it is likely that the latter may have adsorbed on the pore mouth as well as pore wall, this way offering much lower pore diameter than 1.8 nm to the flow of dye solution.