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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.

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Kaolin (china clay) is a rock material that is very rich in kaolinite. A kaolin ore from Debre Tabor, Ethiopia containing 59.2 wt% SiO2, 24.9 wt% Al2O3, 2.4 wt% Fe2O3, and 8.22 wt% loss on ignition (LOI) was physically beneficiated, chemically leached, and thermally treated for possible industrial use, especially for ceramic membrane fabrication. The leaching experiments were carried out using oxalic acid solutions as leaching reagents for the iron extraction process. The effect of acid concentration, reaction temperature, and contact time on iron leaching was investigated. It was determined that the rate of iron extraction increased with the oxalic acid concentration, leaching temperature, and contact time. A substantial reduction of iron oxide (2.4 to 0.36 wt%) from the raw kaolin was observed at operating conditions of 2.0 M oxalic acid, the temperature of 120 °C, and contact time of 120 min. A maximum kaolin whiteness index of 81.4% was achieved through this leaching process. Finally, the physically beneficiated, chemically leached, and thermally treated kaolin raw material was used to fabricate a low-cost kaolin-based ceramic membrane. After firing at 1100 °C the ceramic membrane was found to have a mass loss of 11.04 ± 0.05%, water absorption of 8.9 ± 0.4%, linear shrinkage of 14.5 ± 0.05%. It was demonstrated to be chemically stable, having less than 3% mass loss in acid solution, and less than 1% mass loss in alkali solution. The newly developed membranes have thus properties comparable to commercial ceramic membranes.

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