Novel Poly(ionic liquid) Augmented Membranes for Unconventional Aqueous Phase Applications in Fractionation of Dyes and Sugar.

Sandrina Depaz,Sumith Ranil Wickramasinghe,Arijit Sengupta,Arijit Sengupta,Yu-Hsuan Chiao

doi:10.3390/polym13142366

Sandrina Depaz, Sumith Ranil Wickramasinghe + Show 3 more

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https://doi.org/10.3390/polym13142366

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Abstract

Poly(ionic) liquid (PIL) augmented membranes were fabricated through self-polymerization of 2-vinyl pyridine and 4-vinyl pyridine followed by dopamine triggered polymerization and bridging with inert polyamide support. The resulting membranes acquired a positive surface charge with a high degree of hydrophilicity. Fourier transformed Infra-red (FTIR) and Energy dispersive X-ray (EDX) spectroscopic investigation revealed the successful augmentation of PIL surface layer, whereas surface morphology was investigated through scanning electron microscopy (SEM) imaging. This manuscript demonstrates pi electron-induced separation of dyes with the trend in permeability: Coomassie Brilliant Blue G (CBBHG) > Remazol Brilliant Blue R (RBBR) > Eichrome Black T (EBT) > Congo Red (CR). CBBG exhibited extended conjugation over large aromatic domain. RBBR and EBT were associated withtheelectron-donating -NH2 group and electron-withdrawing -NO2 group, respectively, hence pi electron density on aromatic ring varied. The steric repulsion between two pairs of ortho hydrogens (Hs) in biphenyl moieties of CR resulted in deviation of planarity and hence aromaticity leading to the lowest permeability. The sugar fractionation followed the trend: Galactose > Mannose > Fructose > Glucose > Xylose. More hydroxyl (-OH) groups in sugars and their conformational alignment in the same direction, exhibited more lone pair of electrons leading to more interaction with PIL and hence better permeability. Pentose showed poorer permeation than hexose, whereas aldose showed better permeation than ketose.

Highlights

Ionic liquids (ILs) have been a subject of interest in recent decades due to their very low volatility, non-flammability, high heat capacity, solvating power, polarizing ability, high ionic conductivity, chemical, radiolytic and thermal stability [1,2,3,4]
Novel poly(ionic liquid) based membranes were fabricated on polyamide support layer by bridging through dopamine
The Poly(ionic) liquid (PIL) augmentation was found to enhance the hydrophilicity of the membrane surface

Summary

Introduction

Ionic liquids (ILs) have been a subject of interest in recent decades due to their very low volatility, non-flammability, high heat capacity, solvating power, polarizing ability, high ionic conductivity, chemical, radiolytic and thermal stability [1,2,3,4]. The uniqueness of ionic liquids prompt advancement in the fields of synthesis, catalysis, separations, electrochemistry, energy, nuclear science, hydrometallurgy, biotechnology, water treatment and biomass processing [7,8,9,10,11]. Their customizability of chemical and physical properties through different combinations of cations and anions are advantageous [11]. A major economic drawback for the use of ionic liquids istheir high synthesis cost [15] Another challenge is developing “green” processes for solute recovery as large amounts of energy are needed [16]

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