Enhancing the removal of organic micropollutants by nanofiltration membrane with Fe (III)–tannic acid interlayer: Mechanisms and environmental implications

Abstract

<p>Nanofiltration technology has been applied in many water treatment scenarios. However, conventional thin-film composite (TFC) membranes fail to remove emerging organic micropollutants (OMPs) efficiently. Here we applied thin-film nanocomposite membrane with an interlayer (TFNi) of Fe (III)-tannic acid to remove various OMPs, such as endocrine disrupting chemicals (EDCs), pharmaceutically active compounds (PhACs), and perfluoroalkyl substances (PFASs). Compared to the pristine TFC membrane, TFNi membrane exhibited crumpled morphology and its rejection layer possessed higher cross-linking degree, higher mass density of polyamide, and smaller average pore size with narrower distribution. Significant enhancement in water-OMPs permeability selectivity of PhACs and PFASs was observed. The mechanism lies in the effects of interlayer in improving the membrane permeance to water and meanwhile reducing the permeance to some OMPs by enhancing size exclusion effects. This work confirms the effectiveness of using TFNi membrane to simultaneously enhance the OMPs rejection and water permeance. The unraveled mechanism might inspire the development of high-performance nanofiltration membranes targeting OMPs removal.</p>