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

Abstract

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 μm, 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 μm 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.

Progress and Prospects of Nanocellulose-Based Membranes for Desalination and Water Treatment

“…In both the fundamental and applied aspects of PV, significant progress and exciting breakthroughs have been made in recent decades [ 112 ]. In PV applications, different studies have focused on the modification of nanocomposite membranes fabricated with nanocellulose [ 113 ]. Different researchers have developed nanocomposite membranes with nanocellulose that show outstanding results in terms of selectivity, salt rejection, permeability, [ 114 ] and also desirable and effective surface morphology that enhance the membrane efficiency and its mechanical properties [ 115 ].…”

“…Prihatiningtyas and group [ 113 ], by utilizing a solution casting method, fabricated cellulose triacetate/cellulose nanocrystals (3%) (CTA/CNCs) nanocomposite pervaporation membranes. The membrane was modified to a sponge-like structure which offered the evidence for incorporation.…”

Cellulose triacetate/LUDOX‐SiO2 nanocomposite for synthesis of pervaporation desalination membranes

“…The peak at 1370 cm −1 is attributed to the asymmetric bending of CH, the peak 1216 cm −1 belongs to CO stretching, and the peak at 1023 cm −1 corresponds to pyranose ring COC stretching (see Figure 5(a)). As Figure 5(b) shows, the characteristic peaks at 2963 and 3484 cm −1 are corresponding to the stretching vibration of CH and OH, respectively 42 . Compared with the pristine CTA membrane, the new peaks at 798 and 1121 cm −1 (see Figure 5(a)) represents the SiO bending and SiOSi symmetric stretching 43,44 .…”

“…As Figure 5(b) shows, the characteristic peaks at 2963 and 3484 cm −1 are corresponding to the stretching vibration of C H and O H, respectively. 42 Compared with the pristine CTA membrane, the new peaks at 798 and 1121 cm −1 (see Figure 5(a)) represents the Si O bending and Si O Si symmetric stretching. 43,44 The decreasing percentage of peak transmittance at 798 and 1121 cm −1 correlates to the higher SiO 2 content in the membrane.…”

Oxone®-Mediated TEMPO-Oxidized Cellulose Nanomaterials form I and form II

“…The bottle was continuously mixed in a bottle roller over 72-120 h at room temperature. All films were generated by non-solvent induced phase separation [39]. Sample nanocomposite films and the control CTA films were cast from the same batches of each respective solution composition shown in Table 1.…”