Blend polyvinylidene fluoride/surface modifying macromolecule hollow fiber membrane contactors for CO2 absorption

Abstract

Recently, membrane contactors have attracted attentions as an efficient and flexible technology for CO2 capture. In the present work, blend hydrophobic polyvinylidene fluoride (PVDF) hollow fiber membranes were prepared via a dry–wet phase-inversion process. Surface modifying macromolecule (SMM) was introduced to improve the membrane properties for CO2 absorption in gas–liquid membrane contactors. The effect of SMM concentration in the polymer dope, air gap distance and bore fluid composition on the structure and performance of the membranes were investigated. By increasing SMM in the polymer dope, the membranes presented smaller mean pore sizes, higher permeability and surface hydrophobicity. Using 2wt.% SMM, the membranes prepared at 24cm air gap showed larger mean pore size, higher hydrophobicity and lower permeability compared to those prepared at 0cm air gap. By using 60wt.% DMAc aqueous solution as the bore fluid, the membrane permeability and CO2 flux significantly improved. Maximum CO2 absorption flux of 6.8×10−4mol/m2 s was achieved at absorbent velocity of 0.025m/s. The surface modified membrane demonstrated about 10% gradual CO2 flux reduction for over 140h of the long-term operation. In conclusion, by improving surface hydrophobicity of the membrane, a long-term stable operation can be achieved for practical implication of gas–liquid membrane contactor technology.