A crosslinked polyeugenol-based polymer inclusion membrane for the selective removal of malachite green from metal-containing wastewater

Malachite green (MG) requires selective separation from complex wastewater matrices containing coexisting metal ions. In this study, we developed a process-engineered polymer inclusion membrane (PIM) incorporating a crosslinked bio-based carrier, polyeugenol–bisphenol A diglycidyl ether (Poly-BADGE 4:1), and evaluated its applicability for MG removal from aqueous solutions. We systematically investigated the effects of source-phase pH, receiving phase HNO₃ concentration, membrane thickness, carrier concentration and transport time. With optimal conditions (pH 7.0, 0.75 M HNO₃, 0.33 mm membrane thickness, 0.07 M Poly-BADGE 4:1 carrier concentration, and 21 h), the PIM exhibited an MG removal efficiency of 82.24%. In simulated mixed wastewater containing Pb(II) and Cu(II), MG removal decreased to 65.13% due to competitive interactions, while preferential removal of MG over metal ions was maintained. The membrane maintained its chemical and morphological integrity during the transport experiments, as evidenced by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM) characterization. These results demonstrate the potential of Poly-BADGE–based PIMs as a selective polishing unit for dye-contaminated, metal-rich wastewater in advanced treatment schemes.