Effect of Different Additives on Separation Performance of Flat Sheet PVDF Membrane Contactor

Abstract

This paper investigates effects of different additives on morphology and subsequently, separation performance of asymmetric flat sheet Polyvinylidene fluoride (PVDF) membranes to separate CO₂ using membrane contractor. Five different additives from different chemical families including Lithium chloride (salt), Polyethylene glycol 400 (polymer), glycerol (weak anti-solvents), methanol (alcohols) and acetic acid (weak secondary solvents) were used for controlling the morphology of the fabricated membranes. The fabricated PVDF membranes were applied to separate CO₂ from a gas mixture of (20/80 wt/wt) CO₂/N₂ by contacting with (20/80 wt/wt) Monoethanolamine/H₂O as absorbent. The investigations revealed that among the all considered additives, glycerol has the most promising effect on the performance of CO₂ separation from the feed gas mixture. Effects of operational parameters such as flow rate and temperature of absorbents on the separation performance were also studied. Investigations showed that the lowest level of temperature (30 ºC) and the highest level of the flow rate of absorbent (500 ) provide better separation performance. Additionally, the presence of glycerol increased absorption performance (η) from 0.63 to 0.78 (at the lowest level of flow rate) and from 0.79 to 0.91 (at the highest level of flow rate) compared to the bare PVDF membranes.