Improvement of hybrid liquid membrane performance in removal of cadmium from wastewater using GO filled-polyethersulfone membrane

The removal of cadmium as a heavy metal using a hybrid liquid membrane consisting of an organic liquid phase membrane surrounded by two supporting polymeric membranes was investigated in the present study. The supporting membranes were mixed matrix membranes consisting of graphene oxide (GO) incorporated in polyethersulfone (PES) matrix. The organic liquid membrane was trioctylamine (TOA) as the carrier dissolved in kerosene as the solvent. The synthesized GO and the fabricated supported membrane were characterized using X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), atomic force microscopy (AFM), and optical contact angle (OCA). The effects of GO content in the supporting membrane, carrier concentration, pHs of feed and stripping phases, feed concentration, temperature, mixing intensity, acid type, and organic phase thickness on cadmium removal were studied. The GO-containing PES supporting membrane showed higher cadmium removal efficiency than that of the unfilled PES membrane in the process owing to the higher hydrophilicity and pore size of the fabricated membrane as well as the membrane's surface charge that promotes the mass transfer at the feed/liquid phase interface. The removal efficiency of up to 90% could be attained at mixing intensity of 500 ppm, temperature of 60 degrees C, GO content of 0.2%, carrier concentration of 0.1 M, feed phase pH of 1.8, and a stripping phase pH of 13.