Development of Electrospun Cellulose Acetate Nanofiber-Based Membranes for Filtration Application

The present study aims to produce fully biobased nanofibrous membranes for water decontamination purposes. Cellulose acetate was chosen to produce membranes by electrospinning, and cellulose nanocrystals were chosen to functionalize these mats, providing functional groups able to bond with pollutants such as heavy metals present in wastewaters. The experiments were run varying the electrospinning parameters in order to determine the conditions under which the best defect-free membranes were obtained. Electrospinning a solution of 20wt% CA of average molecular weight equal to 30kDa, with a tip-to-collector distance of 20cm, an applied voltage of 20kV and a flow rate of 2mL/h proved to be the most promising conditions. The composition, the morphology and the functional properties of the as-spun membranes were characterized with Fourier transform infra-red (FTIR), scanning electron microscope (SEM), Brunauer–Emmett–Teller (BET) and water vapor transmission rate (WVTR), respectively. The electrospun membranes consisted of very porous networks of nanofibers with smooth surface and average diameter of 325 ± 82 nm. Functionalization of the membranes was carried out through impregnation using filtration with two types of cellulose nanocrystals suspensions, CNCsa and CNCbe. Flux measurements and copper and silver adsorption tests were run on the modified membranes as well as on the as-spun mats. The high surface area of the mats, their high flux and water vapor permeability, were considered beneficial for water remediation by adsorption purposes. The modification with CNCbe led to conclusive results in term of adsorption but it also led to a drastic reduction of the flux permeability. This could be explained respectively by a higher functionality of CNCbe, higher retention of nanocrystals on CA membrane and by the formation of a nanocrystals film on the electrospun mat during impregnation step. The modification with CNCsa did not lead to conclusive results in term of adsorption even if it did not affect the permeability of the membrane. This could be explained by the lower retention of the nanocrystals on the CA fibers during the impregnation. The study showed that CA based membranes functionalized with cellulose nanocrystals can have potential application in removal of heavy metal ions by water cleaning.Validerat; 20141219 (global_studentproject_submitter