Effect of SMM concentration on morphology and performance of surface modified PVDF hollow fiber membrane contactor for CO2 absorption

Surface modified polyvinylidene fluoride (PVDF) hollow fiber membranes were fabricated via a dry-wet phased inversion process. Surface modifying macromolecules (SMMs) (0, 2, 4 and 6 wt.%) were used as additives in the spinning dope. During phase inversion SMM migrates to the membrane surface, resulting in different surface morphology and surface chemistry. The surface modified PVDF membranes showed the larger pore size, higher gas permeance, effective surface porosity, contact angle and overall porosity but lower critical water entry pressure compared to the PVDF hollow fiber membrane without SMM. The performance of the surface modified membrane in contactor application for physical CO2 absorption was investigated by the fabricated gas-liquid membrane contactor module, where distilled water was used to dissolve CO2. It was found that the liquid phase resistance was dominant in the absorption experiment. The results show that the surface modified PVDF membrane has a higher performance compared to control PVDF membrane. By increasing SMM concentration in the spinning dope, the CO2 absorption flux increased significantly. With the membrane prepared from 6 wt.% of SMM in the spinning dope, a maximum CO2 absorption flux of 5.4 × 10−3 mol/m2 s was achieved at 300 ml min−1 of absorbent flow rate, which was almost 650% more than the fabricated membrane without SMM.