Does Hydrophilic Polydopamine Coating Enhance Membrane Rejection of Hydrophobic Endocrine-Disrupting Compounds?

Abstract

Endocrine-disrupting compounds (EDCs), an important class of micropollutants with potent adverse health effects, are generally poorly rejected by traditional thin film composite polyamide membranes and thus pose significant risks in membrane-based water reclamation. We hypothesize that membrane rejection of hydrophobic EDCs can be enhanced by a hydrophilic surface coating. Using polydoamine (PDA) as a model hydrophilic coating layer, the PDA-coated NF90 membrane experienced an up to 75% reduction in the passage of bisphenol A compared to the control (NF90 without coating). Meanwhile, we also observed a systematic increase in the level of rejection of three hydrophobic parabens with an increase in PDA coating time. In contrast, there were no systematic changes in the rejection of neutral hydrophilic polyethylene glycol, which suggests that the enhanced rejection of EDCs was due to weakened EDC− membrane hydrophobic interaction. Further sorption tests revealed that the hydrophilic PDA coating could effectively decrease the rate of sorption of EDCs by the membrane, which is responsible for the improved rejection as predicted by the solution− diffusion theory. This study reveals an exciting opportunity for engineering membrane surface properties to enhance the rejection of targeted micropollutants, which has important implications in membrane-based water reclamation.

The influences of polydopamine immersion time on characteristics and performance of polyvinylidene fluoride ultrafiltration membrane

“…In addition, in wavenumber 2878 cm -1 MATEC Web of Conferences 197, 09007 (2018) https://doi.org/10.1051/matecconf/201819709007 AASEC 2018 appears a peak from stretching of aliphatic C-H group, and a new peak at 1509 cm -1 evidencing the presence of N-H bending. These results are consistent with those reported in other studies [26][27][28][29].…”

Nanofiltration for drinking water treatment: a review

“…6). For example, a hydrophilic polydopamine coating on a commercial NF90 membrane could significantly enhance its rejection of hydrophobic EDCs [121]. Similar phenomena were also observed in the cases of using tannic acid-iron based NF membrane (Fig.…”

“…On the other hand, organic contaminants with strong hydrophobicity and/or high polarity are often poorly rejected by NF membranes, e.g., < 50% for endocrine disrupting compounds (EDCs) by NF90 [121] and NF270 membranes [31]. The hydrophobic interactions between EDCs and membrane facilitated the partition of these compounds into membrane material (e.g., polyamide) following by the diffusion through the membrane [122,123], resulting in the high permeance of EDCs (thus low rejection).…”

“…The selectivity of NF membrane can be tailored through suppressing the passage of targeted solutes and/or accelerating water transport across the membrane. For example, membrane surface properties (e.g., charge [181], pore size/distribution [15], and hydrophilicity [121]) can be tuned through surface modification to reduce the partition of pollutants into membrane thereby enhancing their rejections. Introduction of additional components (e.g., nanofillers and interlayer) into the membrane matrix (e.g., TFN and TFNi membranes) could often facilitate water transport across the membrane because of the creation of additional water channels and/or reduced membrane thickness [24,26].…”

In Situ Modification of Reverse Osmosis Membrane Elements for Enhanced Removal of Multiple Micropollutants

“…Surface modification of NF/RO membranes by graft polymerization was shown to be an appealing way to improve micropollutant removal [ 33 , 35 , 36 , 37 , 38 ]. The concentration polarization (CP)-enhanced procedure, whereby a mixture of suitable monomers and initiators is simply filtered through the membrane, resulting in enhanced polymerization at its surface, offers a particularly facile way to form a modifying coating layer on top of the membrane and minimize monomer consumption [ 35 , 38 ].…”