Carbon capture by alkaline absorbent using octadecyltrichlorosilane modified PVDF/TiO2 membrane

Abstract

Carbon capture efficiency of membrane gas absorption was improved using a nearly superhydrophobic membrane. This membrane, polyvinylidene fluoride (PVDF) membrane, was blended with TiO2 nanoparticles and post-modified with octadecyltrichloro silane to reduce wetting. Wetting reduction is important to minimize mass transfer resistance in membrane pores during carbon capture. The hydrophilic TiO2 nanoparticles reduced membrane pore size and hydrophobicity in dual bath coagulation, but they offered active sites for silane modification as proven by Fourier-transform infrared spectra to achieve a water contact angle up to 148.8o. A non-wetting surface near to Cassie-Baxter state was formed due to the nano-roughness of TiO2 nanoparticles and hydrophobic functional groups of silane. The modified membrane showed higher CO2 absorption flux in comparison to the neat PVDF membrane, as much as 114% improvement. The modified membrane also achieved faster carbon capture into water. Furthermore, PVDF and PVDF/TiO2 membranes modified with octadecyltrichloro silane in ethanol (volume ratio of 5 : 50) were less affected by NaOH absorbent, displaying great potential for carbon capture and storage using alkaline waste.