Effects of an Alternating Magnetic Field towards Dispersion of α-Fe2O3/TiO2 Magnetic Filler in PPOdm Polymer for CO2/CH4 Gas Separation.

Yun Kee Yap,Pei Ching Oh

doi:10.3390/membranes11080641

Abstract

Magnetic-field-induced dispersion of magnetic fillers has been proven to improve the gas separation performance of mixed matrix membranes (MMMs). However, the magnetic field induced is usually in a horizontal or vertical direction. Limited study has been conducted on the effects of alternating magnetic field (AMF) direction towards the dispersion of particles. Thus, this work focuses on the incorporation and dispersion of ferromagnetic iron oxide–titanium (IV) dioxide (αFe2O3/TiO2) particles in a poly (2,6-dimethyl-1,4-phenylene) oxide (PPOdm) membrane via an AMF to investigate its effect on the magnetic filler dispersion and correlation towards gas separation performance. The fillers were incorporated into PPOdm polymer via a spin-coating method at a 1, 3, and 5 wt% filler loading. The MMM with the 3 wt% loading showed the best performance in terms of particle dispersion and gas separation performance. The three MMMs were refabricated in an alternating magnetic field, and the MMM with the 3 wt% loading presented the best performance. The results display an increment in selectivity by 100% and a decrement in CO2 permeability by 97% to an unmagnetized MMM for the 3 wt% loading. The degree of filler dispersion was quantified and measured using Area Disorder of Delaunay Triangulation mapped onto the filler on binarized MMM images. The results indicate that the magnetized MMM presents a greater degree of dispersion than the unmagnetized MMM.

Highlights

Filler agglomeration has often been reported to worsen the gas separation performance of mixed matrix membranes (MMMs) [1]
Priming only reduces agglomeration up to the maximum weight loading of the filler, mechanical dispersion places the filler at risk of being damaged, and functionalization and dual fillers require the right synthesis and pairing of materials to work effectively [3,4,5,6]
Besides the conventional method of filler dispersion, several works have been published on the implementation of a magnetic field to manipulate the alignment or dispersion of magnetic fillers to improve the gas separation performance

Summary

Introduction

Filler agglomeration has often been reported to worsen the gas separation performance of mixed matrix membranes (MMMs) [1]. This phenomenon is typically attributed to the nature of nano or submicron-sized fillers, wherein the attraction between particles is governed by their strong van der Waal forces, hydrogen bonds, or high surface energy [2]. Researchers often introduce various methods to reduce agglomeration or improve the dispersion of fillers via the physical or chemical modification of the filler (e.g., priming, mechanical dispersion, covalent or non-covalent functionalization, dual fillers). Each of these methods has its respective drawbacks. It prevented filler sedimentation in the polymer phase [8]

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Results