Synthesis and Characterization of Polyaniline-Polyimide Thin-film Composite Membranes for Vegetable Oils/Solvent Separation

The recovery of solvents from the extracted oils using conventional thermal separation processes i.e. distillation or evaporation is often an energy-intensive process. To provide an energy-efficient alternative, an organic solvent nanofiltration thin-film composite membrane was prepared by depositing a thin layer of polyaniline (PANI), a selective layer, via interfacial polymerization on a crosslinked polyimide (XPI), a base ultrafiltration support membrane, to provide selective transport of constituents of a miscella. The membrane was characterized by microscopic, spectroscopic, and thermal analysis. The evaluation of the separation performance was carried out by a dead-end stirred cell using three vegetable oils. For sunflower, corn, and castor oil/n-hexane mixtures, the membrane resulted in a % rejection of 50, 56, and -44, respectively. A comparison of mass flux and rejection of corn and castor oils suggests that the PANI/XPI membranes showed a strong ion-exchange behavior significantly recognizing charge macromolecules due to the presence of charged emeraldine PANI.