Oxidized carbide-derived carbon as a novel filler for improved antifouling characteristics and permeate flux of hybrid polyethersulfone ultrafiltration membranes

Polyethersulfone (PES) is a widely used polymer for ultrafiltration (UF) membrane fabrication. In the current study, carbide-derived carbon (CDC) oxidized by acid treatment was utilized as a filler to fabricate a novel PES composites UF membranes. The successful oxidation of CDC was validated from presence of oxygen containing functional groups and improved oxygen content, from 5.08 at.% for CDC to 26.22 at.% for oxidized CDC (OCDC). The OCDC PES UF membranes were prepared at different loadings of OCDC between 0.5 and 3.0 wt%. The membrane porosity, pore size and surface free energy found to be improved while a noticeable reduction in water contact angle was observed with OCDC loading implying the improved hydrophilicity of PES membranes. Consequently, the pure water flux found to improve from 151.6 to 569.6 (L/(m2. h)) for the 3.0 wt% modified OCDC membrane (M-3) which is 3.8 folds of the bare PES membrane. The antifouling characteristics were evaluated by humic acid (HA) filtration. The results revealed a significant enhancement in HA rejection with OCDC loading, the highest rejection was 96.8% for M-3 membrane. Additionally, the adsorption capacity of OCDC modified membranes found to decrease with OCDC loading indicating improved rejection of HA from the membrane surface. Moreover, M-3 demonstrated the maximum flux recovery ratio (FRR) of 92.3%. Reusability of the fabricated membranes was evaluated by deionized water/humic acid cycling filtration. The FRR was higher than 86.7% over three cycles of pure water/HA filtration for 140 min, indicated the excellent stability and reusability of the membranes. Overall, the OCDC was an effective filler for enhancing the PES UF membranes antifouling and permeability properties.