Determination of mass transfer rates in PVDF and PTFE hollow fiber membranes for CO2 absorption

The gas-liquid mass transfer accompanied by chemical reaction was studied in a membrane absorber for the separation of CO2 from mixture gases. The membranes used were made of polytetrafluoroethylene (PTFE) and polyvinylidenefluoride (PVDF) and the aqueous MEA solution was used as an absorbent possessing a high chemical reaction with carbon dioxide. The numerical model for the CO2 concentration profile in a fiber was developed, and the influence of its flux on the external mass transfer resistances, including gas and membrane, was simulated with this numerical model and compared with the experimental results. Experimentally, it is found that absorption rate per surface area was higher in PVDF membrane than that in PTFE membrane because of the non-wetted condition of membrane pore. The membrane pore wetted with an absorbent showed the low absorption performance by high membrane resistance. We could predict the liquid resistance and membrane-gas resistance (external resistance) from experimental and numerical mass transfer coefficient data.