Bio-inspired PDA@WS2 polyacrylonitrile ultrafiltration membrane for the effective separation of saline oily wastewater and the removal of soluble dye

Abstract

The use of membrane filtration for saline oily wastewater separation remains challenging for industry application despite the progress in membrane technology. The use of two-dimensional (2D) nanoparticles is well known for improving membrane properties, yet they are still vulnerable to fouling and operational inconsistencies. In providing solutions, bio-inspired PDA@WS2 PAN UF membrane was fabricated with tailored molecular weight cutoff (MWCO) and excellent selectivity for effective removal of oil and dye in a saline environment. At high salinity, the modified membrane with the lowest MWCO of 5308.53 Da and Stokes diameter of 2.17 nm showed sufficient separation of oil and dye of about 99.53% and 98.23% respectively. Concurrently sustaining high water permeability of 58.57 L m−2h−1 with free transport of monovalent and divalent salts. Moreover, due to the synergistic effect of the adhesive PDA with WS2 nanosheet and PAN, the modified membrane displayed outstanding oil repellency and antifouling properties of about 98.6%. Furthermore, excellent thermal stability between the temperature of 100–900 °C, and pressure stability ranging from 1 bar to 6 bar of the modified membranes was reported. Overall, the operational stability of the modified membrane was sustained with high removal of oil and dye, and permeation of salt over a 90 h long-term operation. Consequently, this study demonstrates the potential application of bio-inspired PDA@WS2 PAN membrane for the treatment of saline oily wastewater.