An efficient immersing strategy for enhancing the separation performance of microfiltration carbon membranes for oily wastewater

Here, an immersing strategy was designed to modify the porous structure of microfiltration carbon membranes (MFCMs) made by the pyrolysis of phenolic resin-based plates. The thermal stability of precursors, the functional groups, porous structure, microcrystalline structure, microscopic morphology and surface wettability of MFCMs were characterized by TGA, FT-IR, XRD, SEM, TEM and water contact angle, respectively. The effects of the concentration of immersing solution, soaking time and operational conditions on the separation performance of MFCMs for oily wastewater were investigated. In addition, the anti-fouling ability of the MFCMs was further examined. The results showed that the average pore size and porosity of MFCMs decreased after immersing modification. When the modification condition was adopted at the immersing solution concentration of 3% and soaking time of 60 s, the resultant MFCMs exhibited the minimum average pore size of 0.13 μm and a porosity of 31.96%. At the same time, the optimal separation performance was achieved at 99.85% for oil rejection and 392.16 Kg/m2•h•MPa for water permeation flux. In addition, the oil rejection almost remains intact during antifouling ability test, except for a slight drop trend of water permeation flux. It is evident that the facile immersing protocol holds a promise for effectively modifying MFCMs in the treatment of oily wastewater.