Manipulating membrane hydrophobicity by integrating polythylene-coated fume silica in PVDF membrane

Abstract

Membrane gas absorption (MGA) as an emerging technology exhibits superior advantages in comparison to conventional carbon dioxide (CO2) absorption processes. However, the decrease in membrane flux, induced by membrane wetting is a significant issue to be pondered upon. Thus, fabrication of an antiwetting composite membrane is essential to retain and sustain the MGA performance. In this work, silica nanoparticles (SiNPs) is first coated with hydrophobic low-density polyethylene (LDPE). Then, integrating LDPE-HMDS/SiNPs fillers into the polyvinylidene fluoride (PVDF) matrix to increase its hydrophobicity. The incorporation of LDPE-coated silica into PVDF polymer enhanced the contact angle values from 71.8° to 111.8°, indicates the improvement of membrane anti-wetting ability. Despite the similar finger-like layer laid on top of the sponge-like structure for pristine and composite membranes, the incorporation of LDPE-HMDS/SiNPs has reduced in the length ratio of finger-like to sponge-like layer. The changed in the membrane morphology induced higher membrane hydrophobicity which prevent membrane from getting wet easily especially in long term of operation. In addition, EDX surface mapping and lining profiles clearly proved that the LDPE-HMDS/SiNPs were distributed evenly in the composite membranes indicates the good interfacial compatibility between PVDF polymer and LDPE-coated silica. In term of CO2 absorption flux, the embedment of LDPE-HMDS/SiNPs in PVDF polymer matrix demonstrated 2.4x10-3 mol/m2.s which was 2 times higher than that of the pristine membrane. This means the incorporation of LDPE-HMDS/SiNPs into the PVDF membrane has still played a pivotal role in overcoming membrane wetting drawbacks when in contact with the liquid absorbents.