The oil-removal efficiency of the PDA-coated membranes and is comparable to the corresponding uncoated membrane (). However, the permeance was reduced to approx. 50–60 L m−2 h−1 bar−1 due to the PDA growth on the membrane surface. The coating layer is known to increase the hydraulic resistance, and the membrane performance is dominantly governed by the thicker and more compact PDA layer, which can lead to lower permeance [52]. The reduction of the GO resulted in membranes with inferior performance with respect to both oil-removal efficiency and permeance, since the rGO increased the hydrophobicity of the membrane.