Nanofibrous membranes with surface migration of functional groups for ultrafast wastewater remediation

The development of highly efficient adsorbents with a fast adsorption rate and high adsorption capacity presents an enticing prospect for wastewater remediation. In this paper, a novel ultrafast adsorption nanofibrous membrane (UFAM) for organic dyes was prepared through a simple functional group surface migration method. An amphiphilic copolymer of methyl methacrylate and sodium styrene sulfonate was synthesized in a mass ratio of 3 : 2 by free radical polymerization and further blended into polyethersulfone (PES) to prepare functionalized PES nanofibrous membranes by electrospinning technology. Just by soaking in water and lyophilization, the hydrophilic and negatively charged sulfonate groups migrated and concentrated on the membrane surface, and the obtained UFAM was found to be exceptionally efficient in the removal of methylene blue (MB) dye from aqueous solution. Especially, an ultrafast adsorption rate for MB with an adsorption equilibrium time of within 5 min was reported for the first time. The mechanism of the ultrafast adsorption based on the sulfonate group migration and enrichment was also especially explored in this study. In addition, the UFAM also showed excellent performance of recyclability, dynamic filtration–purification, selective adsorption for cationic dyes from mixed dye solutions and smart filtration–separation for cationic and anionic dyes. Therefore, we envision that this study will not only provide a new strategy to construct low-cost and highly efficient adsorbents, but also demonstrate their potential applications in the removal of organic dyes on a large scale.