110th Anniversary: Cellulose Nanocrystals as Organic Nanofillers for Cellulose Triacetate Membranes Used for Desalination by Pervaporation

Membranes with a high water flux and excellence in separating NaCl are required in pervaporation (PV) for water desalination. Cellulose nanocrystals (CNCs) are low cost and hydrophilic with good mechanical properties. Therefore, they could potentially enhance the water flux of PV membranes. Cellulose triacetate/cellulose nanocrystals (CTA/CNCs) nanocomposite PV membranes were successfully fabricated via solution casting, aiming to improve the water desalination performance. The effects of CNCs on the membrane morphology, hydrophilicity, mechanical properties, water flux, and rejection were investigated. Incorporating CNCs changed the membrane structure from spongelike to self-assembled structure. PV experiments showed incorporating 3% CNCs into a CTA membrane effectively enhanced the water flux by a factor of 3, from 2.16 kg m(-2) h(-1) to 5.76 kg M-2 h(-1). This was further optimized by reducing the casting blade height from 200 to 100 mu m, thus obtaining a flux of 11.68 kg m(-2) h(-1), while the NaCl rejection remained 99.9%. The CNCs 3%-CTA PV membrane with a casting blade height of 100 mu m also showed a good performance for 12 h of separation. This newly developed PV membrane allows for an excellent separation of water from NaCl. Moreover, it has a substantially increased water flux compared to a pristine membrane and is thus potentially applicable for desalination.