PVDF/CaCO3 composite hollow fiber membrane for CO2 absorption in gas-liquid membrane contactor

Porous hydrophobic polyvinylidene fluoride (PVDF) composite hollow fiber membranes were fabricated via phase inversion method by embedding different amounts of hydrophobic calcium carbonate (CaCO3) nano-particles in the polymer matrix. The effects of nano-particle loadings on the morphology, structure and performance of the spun membranes in gas-liquid contactors were investigated. The incorporation of hydrophobic nano-particles into the polymer network enabled the formation of more abundant and narrower finger-like pores in the composite membranes compared to plain PVDF membrane. Moreover, the addition of nano-particles enhanced the surface roughness, permeation rate, porosity and wettability resistance of the composite membranes. CO2 absorption performance of the fabricated membranes was evaluated via a gas-liquid membrane contactor system. The CO2 flux was improved to some extent by increasing the mixing ratio of CaCO3. Peak absorption performance of 1.52 × 10−3 mol m−2 s−1 at 300 ml/min absorbent flow rate was achieved when 20/100 weight ratio of CaCO3/PVDF was employed. However, further increase of the ratio resulted in a composite membrane with lower absorption performance than the other composite membranes. Moreover, a long-term stability study of the composite membrane with the best CO2 absorption flux showed no decline in performance in the initial 210 h of operation, indicating that the membrane possesses high potential for gas-liquid contactor applications.