Fouling resistance with time at different TMPs.

<p>(A) 10 kPa, (B) 20 kPa, (C) 30 kPa. Error bars represent standard deviations of triplicate tests.</p

Particle size distribution and fractal dimension of DM layers at various TMPs.

<p>(A) median particle size by number, (B) fractal dimension. Error bars represent standard deviations of triplicate tests.</p

Variations of soluble EPS during short-term batch tests.

<p>(A) AS1, (B) AS2, (C) AS3. PS-polysaccharides, PN-proteins, HS-humic substances. Error bars represent standard deviations of triplicate tests.</p

Schematic of anaerobic DM formation with EPS extraction and re-addition.

<p>Schematic of anaerobic DM formation with EPS extraction and re-addition.</p

CLSM images of AS1 (A1-A4), AS2 (B1-B4) and AS3 (C1-C4).

<p>Symbols 1–4: 1 exhibits combination of individual images in 2–4, 2 represents CLSM image of α-polysaccharides (Con A), 3 represents CLSM image of β-polysaccharides (Calcofluor white), and 4 represents CLSM image of proteins (FITC).</p

Variations in (A) specific resistance and (B) porosity of DM layer at the end of filtration.

<p>Error bars represent standard deviations of triplicate tests.</p

Total interaction energy curves of (A) sludge and (B) EPS.

<p>Total interaction energy curves of (A) sludge and (B) EPS.</p

Trade-off between Endocrine-Disrupting Compound Removal and Water Permeance of the Polyamide Nanofiltration Membrane: Phenomenon and Molecular Insights

The polyamide (PA) nanofiltration (NF) membrane has the potential to remove endocrine-disrupting compounds (EDCs) from water and wastewater to prevent risks to both the aquatic ecosystem and human health. However, our understanding of the EDC removal–water permeance trade-off by the PA NF membrane is still limited, although the salt selectivity–water permeance trade-off has been well illustrated. This constrains the precise design of a high-performance membrane for removing EDCs. In this study, we manipulated the PA nanostructures of NF membranes by altering piperazine (PIP) monomer concentrations during the interfacial polymerization (IP) process. The upper bound coefficient for EDC selectivity–water permeance was demonstrated to be more than two magnitudes lower than that for salt selectivity–water permeance. Such variations were derived from the different membrane–solute interactions, in which the water/EDC selectivity was determined by the combined effects of steric exclusion and the hydrophobic interaction, while the electrostatic interaction and steric exclusion played crucial roles in water/salt selectivity. We further highlighted the role of the pore number and residual groups during the transport of EDC molecules across the PA membrane via molecular dynamics (MD) simulations. Fewer pores decreased the transport channels, and the existence of residual groups might cause steric hindrance and dynamic disturbance to EDC transport inside the membrane. This study elucidated the trade-off phenomenon and mechanisms between EDC selectivity and water permeance, providing a theoretical reference for the precise design of PA NF membranes for effective removal of EDCs in water reuse

Trade-off between Endocrine-Disrupting Compound Removal and Water Permeance of the Polyamide Nanofiltration Membrane: Phenomenon and Molecular Insights

The polyamide (PA) nanofiltration (NF) membrane has the potential to remove endocrine-disrupting compounds (EDCs) from water and wastewater to prevent risks to both the aquatic ecosystem and human health. However, our understanding of the EDC removal–water permeance trade-off by the PA NF membrane is still limited, although the salt selectivity–water permeance trade-off has been well illustrated. This constrains the precise design of a high-performance membrane for removing EDCs. In this study, we manipulated the PA nanostructures of NF membranes by altering piperazine (PIP) monomer concentrations during the interfacial polymerization (IP) process. The upper bound coefficient for EDC selectivity–water permeance was demonstrated to be more than two magnitudes lower than that for salt selectivity–water permeance. Such variations were derived from the different membrane–solute interactions, in which the water/EDC selectivity was determined by the combined effects of steric exclusion and the hydrophobic interaction, while the electrostatic interaction and steric exclusion played crucial roles in water/salt selectivity. We further highlighted the role of the pore number and residual groups during the transport of EDC molecules across the PA membrane via molecular dynamics (MD) simulations. Fewer pores decreased the transport channels, and the existence of residual groups might cause steric hindrance and dynamic disturbance to EDC transport inside the membrane. This study elucidated the trade-off phenomenon and mechanisms between EDC selectivity and water permeance, providing a theoretical reference for the precise design of PA NF membranes for effective removal of EDCs in water reuse

Influence of Surface Functional Groups on Deposition and Release of TiO₂ Nanoparticles

A clear understanding of the factors governing the deposition and release behaviors of engineered nanoparticles (NPs), such as TiO₂ NPs, is necessary for predicting their transport and fate in both natural and engineered aquatic environments. In this study, impacts of specific chemistries on TiO₂ NP deposition, as a function of TiO₂ NP concentration and ionic strength/valence, were investigated using self-assembled monolayers (SAMs) with five different ending chemical functionalities (−CH₃, −OH, −COOH, −NH₂, and −CONH₂). The fastest deposition and maximum deposition mass were observed on −NH₂, followed by −COOH, −CONH₂, −CH₃, and −OH, showing that contact angle and zeta potential of surfaces were not good indicators for predicting the deposition. Specific interactions, for instance, between −COOH and −CONH₂ and TiO₂, significantly affected their deposition. Deposition rate increased linearly with TiO₂ NP concentration; however, specific deposition rate was dependent on the type of SAMs. The increase of monovalent (Na⁺) and divalent (Ca²⁺) led to different changes in deposition rates for the SAMs due to different functionalities. Results also showed that favorable SAM (e.g., −NH₂) had lowered release of NPs compared to unfavorable surface (e.g., −OH). The obtained deposition and release behaviors will support more accurate prediction of the environmental fate of nanoparticles