RETRACTED: Polyethylene Coated with MnO₂ Nanoparticles as Thin Film Composite Membranes for Organic Solvent Nanofiltration

A thin film composite (TFC) membrane with superior characteristics for organic solvent nanofiltration (OSN) was successfully prepared. Accordingly, a state-of-the-art polyethylene (PE) membrane support was first prepared through etching the polystyrene (PS)/styrene–ethylene–butylene–styrene (SEBS) phase, as the dispersed phase, from the fabricated PE/SEBS/PS composite using the solvent extraction technique. Different compositions were fabricated so that a suitable ultrafiltration membrane support could be achieved. Due to the high hydrophobicity of the prepared PE membrane support (Etched PE) and lack of polar functional groups on its surface, the impregnation with an m-phenylenediamine (MPD) aqueous solution and, consequently, the formation of the polyamide layer on the PE surface were restricted. Hence, the prepared PE membrane supports were immersed in potassium permanganate (KMnO4) solutions with different concentrations so that the PE surface could be oxidized, by which polar functional groups were generated and manganese(IV) dioxide (MnO2) nanoparticles were also formed on the surface via a relatively strong bond. Next, MPD and trimesoyl chloride (TMC) monomers with different concentrations were utilized for the formation of a cross-linked TFC layer on the MnO2-loaded PE surface. The TFC membranes showed a hydrophilic and defect-free polyamide barrier layer, high separation performance (dye rejection as high as 99.8% for methyl green), methanol permeance of 7 L/m2·h, and high methanol permeance after dimethylformamide (DMF) activation (14 L/m2·h). Furthermore, a superior solvent resistance (dye rejections of more than 98.5, 97.0, 96.0, and 93.5% for methyl green, rhodamine B, crystal violet, and methylene blue, respectively, being immersed in DMF at 75 °C for about 100 days) was exhibited by the prepared membranes, which demonstrated their promising potential in the OSN applications.