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.

Poly(2,6‐dimethyl‐1,4‐phenylene oxide) membrane with magnetic α‐Fe2O3/TiO2 fillers was exposed to varying alternating magnetic field (AMF) duration and frequency. The AMF threshold time was 8 min as mixed‐matrix membrane (MMM) exposed to 11 min experienced an abrupt increase in permeability of CO2 by 785% and CH4 by 1322%. Although quantitative measurements showed relatively excellent values at 11 min, prolonged exposure time reduces selectivity, possibly due to interruption in the polymer‐filler interfacial area densification process. Filler distribution measured quantitatively via optical microscope and MATLAB also revealed that MMM exposed to 3.3 kHz presents the greatest dispersion metric with the least agglomeration. MMM exposed to the frequency of 30 Hz or 330 kHz suffered from either increased agglomeration size or worse dispersion. Consequently, their gas separation performances were lower than MMM exposed to 3.3 kHz. Above a critical frequency, repulsive hydrodynamic forces overcome the attractive forces between magnetic fillers.

Ultrafiltration membrane has been widely used for oily wastewater treatment application attributed to its cost-efficiency, ease of operation, and high separation performance. To achieve high membrane flux, the pores of the membrane need to be wetted, which can be attained by using hydrophilic membrane. Nevertheless, conventional hydrophilic membrane suffered from inhomogeneous dispersion of nanofillers, causing a bottleneck in the membrane flux performance. This called for the need to enhance the dispersion of nanofillers within the polymeric matrix. In this work, in-house-fabricated hydrous manganese dioxide–aluminum oxide (HMO-Al2O3) was added into polyethersulfone (PES) dope solution to enhance the membrane flux through a xylem-inspired water transport mechanism on capillary action aided by cohesion force. Binary fillers HMO-Al2O3 loading was optimized at 0.5:0.5 in achieving 169 nm membrane mean pore size. Membrane morphology confirmed the formation of macro-void in membrane structure, and this was probably caused by the hydrophilic nanofiller interfacial stress released in PES matrix during the phase inversion process. The superhydrophilic properties of PES 3 in achieving 0° water contact angle was supported by the energy-dispersive X-ray analysis, where it achieved high O element, Mn element, and Al elements of 39.68%, 0.94%, and 5.35%, respectively, indicating that the nanofillers were more homogeneously dispersed in PES matrix. The superhydrophilic property of PES 3 was further supported by high pure water flux at 245.95 L/m2.h.bar, which was 3428.70% higher than the pristine PES membrane, 197.1% higher than PES 1 incorporated with HMO nanofiller, and 854.00% higher than PES 5 incorporated with Al2O3 nanofillers. Moreover, the excellent membrane separation performance of PES 3 was achieved without compromising the oil rejection capability (98.27% rejection) with 12 g/L (12,000 ppm) oily wastewater.

Magnetophoretic dispersion of magnetic fillers has been proven to improve gas separation performances of mixed matrix membrane (MMM). However, the magnetic field induced is usually in a horizontal or vertical direction during membrane casting. Limited study has been conducted on the effects of rotational magnetic field direction towards dispersion of particles. Thus, this work focuses on the rearrangement of paramagnetic iron oxide-titanium dioxide (αFe2O3-TiO2) nanocomposite in poly (2,6-dimethyl-1,4-phenylene oxide) (PPOdm) membrane via rotational magnetic field to investigate the dispersion of filler and effects towards its overall gas separation performance. The paramagnetic fillers were incorporated into polymer via dry phase inversion method at different weight loading. MMM with 3 wt% loading shows the best performance in terms of particle dispersion and gas separation performance. It shows the greatest relative particles count and least agglomerates via OLYMPUS™ Stream software with image taken by optical microscope. Relative to pristine membrane, it displays a permeability and selectivity increment of 312% and 71%. MMM with 3 wt% loading was refabricated in the presence of rotational magnetic field to enhance the dispersion of paramagnetic fillers. Results display an increment of selectivity by 8% and CO2 permeability by 46% relative to unmagnetised MMM of 3 wt% loading.