Molecular dynamics simulations of hyperbranched poly(ethylene imine)-graphene oxide nanocomposites as dye adsorbents for water purification

Atomistically detailed molecular dynamics simulations were employed to study the adsorption capacity of graphene-oxide-based (GO) aqueous systems for the methylene blue (MB) dye in the presence of branched poly(ethylene imine) (BPEI) polymers. The polymeric component was either freely mixed or chemi...

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Bibliographic Details
Published inPhysical chemistry chemical physics : PCCP Vol. 23; no. 4; pp. 22874 - 22884
Main Authors Tanis, I, Kostarellou, E, Karatasos, K
Format Journal Article
LanguageEnglish
Published Cambridge Royal Society of Chemistry 20.10.2021
Subjects
Adsorption
Clustering
Dyes
Flakes
Graphene
Methylene blue
Molecular dynamics
Morphology
Nanocomposites
Nanofiltration
Polyethyleneimine
Polymers
Temperature dependence
Temperature effects
Water purification
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Summary:Atomistically detailed molecular dynamics simulations were employed to study the adsorption capacity of graphene-oxide-based (GO) aqueous systems for the methylene blue (MB) dye in the presence of branched poly(ethylene imine) (BPEI) polymers. The polymeric component was either freely mixed or chemically attached to GO. The main focus was the elucidation of the effects originating from the presence of BPEI molecules in the association of MB with the formed GO complexes. The effect of temperature was also examined. It was found that the presence of the cationic BPEI molecules results in the formation of a distinct microenvironment characterized by a polymer-mediated interconnected morphology which promotes the development of larger-sized MB clusters. These clusters were found to form in the vicinity of the GO flakes, increasing thus the adsorption capacity of the dye molecules in the polymer-containing systems. Particularly in the system with the BPEI-functionalized GO flakes, a persistent percolated structure is formed, which results in a more restricted diffusion of the MB molecules, increasing thus significantly their residence time close to the GO surface. The clustering behavior of MB was found to be temperature-dependent in the BPEI-based models, providing useful information regarding the conditions for optimal adsorption performance of such membranes, in nanofiltration processes. Molecular dynamics simulations of aqueous graphene oxide/hyperbranched poly(ethyleneimine) nanocomposites, demonstrated the potential of these systems to physically adsorb "methylene blue" dye molecules, for water purification purposes.
Bibliography:10.1039/d1cp02461b
Electronic supplementary information (ESI) available: Snapshots of the initial configurations of the systems, radial distribution functions arising from the centers of mass of the GO flakes, radial distribution functions arising from the centers of mass of MB, orientational order parameter of the GO, orientational order parameter of the MB molecules, center of mass distribution profiles of the GO molecules in a direction normal to the GO plane, charge distributions along a direction normal to the GO plane, MSD of the centers of mass of the dye molecules, comparison of the self van Hove functions describing the MBs' motion, sulfur (MB) - hydroxyl oxygen (GO) radial distribution functions, sulfur (MB) - hydroxyl oxygen (GO) pair correlation functions. See DOI
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ISSN:1463-9076
1463-9084
DOI:10.1039/d1cp02461b