Preparation of Cellulose Acetate Hollow-Fiber Membranes for CO2/CH4Separation

Abstract

Abstract The effect of ethanol (EtOH) concentration and air-gap distance on the gas separation performance of cellulose acetate (CA) membrane was studied. CA asymmetric hollow-fiber membranes were prepared through a dry/wet spinning process using nonsolvent-induced phase separation from dope solutions containing N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), and EtOH, which were then coated with polydimethylsiloxane. CA hollow-fiber membranes made from C2 dope composition (62 wt% NMP, 23 wt% CA, 10 wt% THF, and 5 wt% EtOH) and air-gap distance of 15 cm exhibited excellent separation properties for CO2 and CH4: 12.9 GPU CO2 permeance and 43.8 CO2/CH4 selectivity. Results indicated that the air-gap distance and ratio of THF/EtOH in the dope solution play an important role in the spinning process and production of a well-organized skin for CA asymmetric hollow-fiber membranes, which are known to affect the CO2/CH4 separation performance. To verify the separation performance of the prepared membranes, a...