Performance of Surface-Modified Poly(ether imide) Hollow-Fiber Membranes in a Membrane Gas-Liquid Contacting Process with Response Surface Methodology

A surface-modifying macromolecule (SMM) was used to enhance the surface hydrophobicity of poly(ether imide) (PEI) hollow-fiber membranes. The membranes were used for a membrane contactor to absorb CO2 with water. The effects of three hollow-fiber fabrication parameters, that is, the PEI concentration in the casting dope, the SMM concentration in the casting dope, and the air gap, on the liquid entry pressure of water (LEPw) and the absorption rate (AR) of CO2 were investigated with response surface methodology. The model developed for LEPw satisfied the criterion for regression but had a low goodness of fit. The model predicted that LEPw would increase with PEI (weight percentage) but decrease with air gap. Furthermore, it showed a minimum value with a change in SMM (weight percentage). The model developed for the AR of CO2 had meaningful statistical parameters and was accurate; this indicated that interactions existed between the fabrication parameters on the AR of CO2. The performance of one of the fabricated membranes was compared with in-house and commercially made hydrophobic membranes in terms of the AR of CO2 with distilled water as an absorbent on the lumen side and pure CO2 on the shell side. The comparison showed a superior CO2 flux in the surface-modified membrane; for example, at a liquid velocity of 0.4 m/s, the surface-modified membrane exhibited a 416% higher AR than the commercial membrane contactor (Celgard MiniModule 0.75X5) made of polypropylene. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 128: 1313-1325, 2013