Ultrafiltration Carbon Membranes from Organic Sol-Gel Process

We present a simple approach for preparing mesoporous carbon membranes on macroporous fly-ash-based ceramic supports via sol-gel polymerization of resorcinol with formaldehyde. The support was dip-coated and dried at 45°C under ambient pressure without a special drying process. The mesoporous carbon membrane was obtained after carbonization under a nitrogen atmosphere. The coating–pyrolysis process only required one cycle. The graphitization degree increased with carbonization temperature, as shown by X-ray diffraction. However, Raman spectroscopy revealed that defects emerged at high carbonization temperature. Scanning electron microscopy clearly showed the mesoporous carbon layer and macroporous support, a uniform carbon layer with thickness less than 1 µm forming on the support. The obtained carbon membrane shows uniform pores and high mesopore volume. The flux of pure water through the mesoporous carbon membrane was as high as 167 L · m⁻² · h⁻¹ · bar⁻¹. The molecular weight cutoff of this membrane was found to be about 20,000 Da.