Molecular Dynamics Insights into the Structural and Water Transport Properties of a Forward Osmosis Polyamide Thin-Film Nanocomposite Membrane Modified with Graphene Quantum Dots

Abstract

An approach combining molecular dynamics (MD) simulations and laboratory experiments was applied to provide new theoretical insights into the chemical structure of polyamide (PA) thin-film composite (TFC) membranes modified with graphene quantum dots (GQDs). Interaction energies, fractional free volumes, mean-square displacements, densities, and water diffusion coefficients were computed for PA and four likely chemical structures of the GQD-embedded PA membranes. These theoretical results aided with experimentally measured water fluxes allowed for determining the most likely structure of the GQD–PA membrane. The compatibility of the GQDs and PA chains was found to be due to the formation of hydrogen and covalent bonds to m-phenylenediamine units. The modified membrane has a higher water diffusivity but a lower overall free volume, compared to the pristine PA membrane. MD simulations in concert with laboratory experiments were found to provide a good understanding of the relationship between the microscopic characteristics and macroscopic transport properties of TFC membranes.

Innovative in situ investigations using synchrotron‐based micro tomography and molecular dynamics simulation for fouling assessment in ceramic membranes for dairy and food industry

“…Molecular dynamics simulation (MDS) could be applied to reveal the interactions between inorganic particles and organic matters 26 . This feature could effectively be applied for prediction of membrane materials behavior at the vicinity of foulants at the molecular scale.…”

Carbon Nanodots from an In Silico Perspective

“…Models of (a) GQD and (b) polyamide P1. Panels c–e: polyamide-GQD systems considered by Salestan et al Reproduced with permission from ref . Copyright 2020 American Chemical Society.…”

“…Interactions with Polymers. Salestan et al 546 presented a combined MD simulations and experimental study to determine the structure of polyamide (PA) thin-film composite (TFC) membranes modified with GQDs.…”

Zwitterion-functionalized MIL-125-NH2-based thin-film nanocomposite forward osmosis membranes: towards improved performance for salt rejection and heavy metal removal

“…Up to this point, many different nanoparticles (NPs) such as metal oxides, carbon nanotubes, graphene oxide, graphene quantum dots (GQDs), zeolites, fullerenol, polyoxometalates (POMs), and covalent organic frameworks (COFs) have been utilized as additive agents to boost the potential and performance of membranes. [24][25][26][27][28][29][30][31] We should point out that there are some prerequisite features that allow nanofillers to fit in this field such as stability in water (to prevent the decomposition of particles), hydrophilicity (to improve the antifouling and water penetration performance), size and separability (to form a more uniform distribution, preventing the accumulation and formation of non-selective pores in PA layer), porous structure (to provide excessive channels for selective water molecules transportation), appropriate interaction, and high compatibility with the polyamide layer (to prevent leaching and leave non-selective pores in the PA layer). With that being said, metal-organic frameworks (MOFs) are excellent candidates to benefit from in this field.…”