A dependence study: Molecular weight of polyethylene glycol (PEG) ON La_0.7Sr_0.3Co_0.2Fe_0.8O_3−δ (LSCF 7328) hollow fiber membrane for oxygen permeation

In an effort to further improvement of LSCF hollow fiber membrane properties in oxygen purification applications, this work studied the use of polyethylene glycol (PEG) with a different molecular weights of 2000, 3400 and 6000 Da as a pore former. A well-prepared hollow fiber membrane was successfully fabricated via extrusion followed by a sintering method. The results showed that the addition of PEG increased the viscosity of the dope suspension and formed a constant asymmetric pore configuration of the membrane after sintering at 1250 °C. The increasing molecular weight of PEG also leads to a decrease in the mechanical strength of the membranes, indicating that finger-like pores were sacrificed by forming irregular pores. The gas tightness was also examined under room temperature which showed that membrane with PEG 3400 achieved the best tightness with the nitrogen permeability of 3.55 × 10⁻⁵ mol·m⁻²·s⁻¹·Pa⁻¹. The oxygen permeation of the membranes was also influenced by the addition of PEG, where the highest oxygen permeation flux of 6.07 × 10⁻⁸ mol·cm⁻²·s⁻¹ was obtained using a hollow fiber membrane with PEG 3400 due to the existence of the lowest dense layer thickness.