Preparation and characterization of a new composite conductive polyethersulfone membrane using polyaniline (PANI) and reduced graphene oxide (rGO)

Abstract

A new polyethersulfone (PES) composite membrane using nanostructures of polyaniline (PANI) and reduced graphene oxide (rGO) was prepared by the phase inversion process. The investigation focused on the use of PANI and rGO as conductive dopants, along with camphorsulfonic acid (HCSA) and dodecylbenzene sulfonic acid (DBSA) for PANI preparation. Higher conductivity was obtained for the membrane doped with PANI-DBSA (4.5 ± 0.3 µS·cm−1). The membrane conductivity was further increased to 9.6 ± 0.8 μS·cm−1, 10 times higher than the conductivity of the PES-control membrane, by incorporating rGO (PES-PANI(DBSA)-rGO(0.2 g). The use of HCSA as PANI dopant resulted in membranes with higher hydrophilicity compared to the ones obtained with the PANI-DBSA. The contact angle reduced from 61.9 ± 2.0° (PES-control) to 45.2 ± 1.5° for PES-PANI(HCSA)-rGO(0.2 g). Moreover, the incorporation of rGO also resulted in fewer but larger macrovoids in the membranes bottom layer and a roughness (Ra) reduction. More specifically, for PES-PANI(HCSA)-rGO(0.2 g), Ra dropped to 2.7 ± 0.4 nm when compared to PES membrane control (11.6 ± 3.4 nm). PANI addition significantly improved membrane permeability, which was further increased with the addition of rGO. Fouling studies revealed that the PES-PANI(HCSA)-rGO(0.2 g) membrane featured higher flux recovery ratio (FRR) (81.3 ± 3.6%) than PES-PANI(DBSA)-rGO(0.2 g) (60.9 ± 5.8%) and PES-control membrane (21.8 ± 5.7%). After electrochemical cleaning, an additional increase of the flux recovery ratio (FRR) was obtained for conductive membranes. In summary, the composite membranes, specially the HCSA-doped membrane, presented improved operating performance and fouling mitigation.