Preparation of an asymmetric microporous carbon membrane for ultrafiltration separation: application to the treatment of industrial dyeing effluent

Abstract

An asymmetric tubular carbon membrane with an ultrafiltration microporous top layer has been prepared using thermosetting phenolic resin and carbon black (CB) as carbon precursors. The membrane was composed of a mesoporous interlayer with an average pore size of 0.6μm deposited by slip casting process on the inner face of a macroporous support. The microporous top layer was deposited by the same process using suspensions of commercial CB powder (44nm average pores size). An initial ultrafiltration membrane with an average pore size of 7.9nm and a thickness of 8.34μm was formed requiring 10 min casting time and a curing–carbonization cycle at 700°C under nitrogen atmosphere. An approach consisting of repeating casting–carbonization cycle was adopted to correct the defects that appeared at the surface. Results showed that an UF-corrected membrane denominated UF-C4 was successfully prepared by adding only one layer after its composition and conditions of deposition were determined. A crack-free UF membrane with a thickness layer of 12.6 μm, a mean pores size of 5.3 nm, and a molecular weight cut-off of 90 kDa was then obtained using only 6 min casting time. It was found that this membrane could be applied efficiently to the treatment of industrial dyeing effluent.