Porous flat sheet membranes were prepared with a commercial grade of cyclic olefin polymer (COP) for CO2 capture using membrane contactor (MC). The membranes were prepared via non-solvent induced phase separation technique using different types of additives, namely, polyvinylpyrrolidone (PVP), polyethylene glycol (PEG400) and sorbitan monooleate (Span 80), and coagulants (acetone and 70/30 wt% acetone/water mixture) were investigated. The prepared membranes were characterized in terms of the thickness (70 - 85 μm), porosity (50 - 80%), mean pore size (158 - 265 nm), bubble pore size (~ 0.6 - 12 μm), liquid entry pressure (1.67- 4.55 bar), water contact angle (~ 94º - 111º), monoethanolamine (MEA) contact angle (~ 67º - 73º) and mechanical properties (tensile strength: 4.53 – 5.15 MPa, elongation at break: 4 – 8% and Young ́s modulus: 190 – 232 MPa). The thermodynamic study of COP membranes proved that a fast phase inversion of the proposed system resulted in a more porous structure. The addition of PEG400 and Span 80 caused delayed demixing and influenced the morphological structure and MC performance. The structural and topographical characteristics of the membranes were also studied. The CO2 absorption test performed at 27 ºC showed that the maximum CO2 absorption flux was around 16×10-5 mol/m2.s using 1M MEA aqueous solution as absorbent with fixed liquid and gas flow rates at 150 L/h and 8.4 L/h, respectively. It was found that the considered additives enhanced the MC performance and affected the CO2 absorption flux.

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