Cellulose triacetate doped with ionic liquids for membrane gas separation

Abstract

Cellulose triacetate (CTA) is a workhorse polymeric membrane material for industrial CO 2 /CH 4 separation. This study investigates the doping of CTA with ionic liquids (ILs) to reduce the crystallinity of the CTA and enhance its affinity with CO 2 , thus increasing CO 2 permeability and CO 2 /light gas selectivity. CTA films doped with 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF 4 ]) and 1-ethyl-3-methylimidazolium dicyanamide ([emim][dca]) were prepared; and the effect of IL loading on properties of the CTA, such as crystallinity, density, degradation temperature, glass transition temperature, and gas transport properties, were determined. The IL doping reduces the glass transition temperature and degree of crystallinity of CTA, increasing gas diffusivity and permeability. The IL doping also increases CO 2 /CH 4 solubility selectivity and CO 2 /N 2 permeability selectivity, due to the affinity of these ILs with CO 2 , compared to light gases such as CH 4 and N 2. This study demonstrates a promising route in manipulating the morphology and gas transport properties of semi-crystalline polymers by doping with ILs.

Carbon dioxide separation using α‐alumina ceramic tube supported cellulose triacetate‐tributyl phosphate composite membrane

“…Figure makes it clear that there was a small reduction in the T g of pure CTA by the addition of TBP into the CTA polymer matrix. This was due to the addition of TBP, which disturbed the CTA polymer chain resulting in the mobility of polymer chains and subsequently reducing the T g …”

“…This is illustrated in Fig. . In this work, the performance of the composite membranes was measured as permeance.…”

“…16. 29,46 In this work, the performance of the composite membranes was measured as permeance. The permeance was converted to permeability by multiplying the permeance by its corresponding membrane thickness.…”

Effects of tertiary amines and quaternary ammonium halides in polysulfone on membrane gas separation properties

“…The density of the polymer films was determined using an analytical balance (Model XS64, Mettler‐Toledo, OH) equipped with density kits at 22 °C . Novec 7300, a fluorinated solvent purchased from 3M Company (St. Paul, MN), was used as an auxiliary liquid, which has low sorption in the polymers.…”

“…Gas sorption in the polymer samples was measured using a gravimetric microbalance apparatus (IGA 001, Hiden Isochema, The United Kingdom) at 35 °C and pressures up to 12 atm. Each polymer sample weighted about 80 mg. Before measurement, the sample was dried under vacuum at 60 °C for at least 10 h. Gas sorption was deemed to reach equilibrium once the microbalance reading remained unchanged for at least 1 h. The gas sorption data were calculated from the weight change of the polymer samples with compensation of buoyancy effect …”