(554a) Functionalized Cellulosoe Nanocrystal (CNC) Filled Reverse Osmosis Desalination Membranes

While much of the world’s population lives in water stressed regions, desalination of saline water via reverse osmosis (RO) is one of the most effective and commonly utilized methods of producing clean drinking water. Despite this, RO desalination is hindered in real word applications due to membrane fouling from biological contaminants including proteins and polysaccharides. These contaminants accumulate on the surface causing a decrease in the effective transmembrane pressure and increase concentration polarization. These combined effects result in decreased water flux and salt rejection. Prior work in our lab has shown that the incorporation of zwitterion functionalized carbon nanotubes into the selective polyamide layer of thin film composite (TFC) membranes results in increased water flux and decreased fouling of the membrane from proteins and polysaccharides. In this work, we have developed thin film nanocomposite (TFN) membranes in which functionalized CNCs are incorporated in the selective layer of the membrane to increase water flux and decrease fouling of the membrane surface.

The CNCs used in this study contained primary hydroxyl groups, as received CNCs, carboxylic acid groups, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanocrystals (TOCNs), tertiary amine functionalized (aCNCs), and zwitterionic functionalized (zCNCs). CNCs were chosen as a nanoparticle filler for the high aspect ratio rod-like morphology, low cost, abundant feed stock, sustainability, and potential for surface modification. Upon adding nanoparticles to the membrane, we have observed an increase, CNC and TOCN, or maintained, aCNC and zCNC, permeate water flux relative to the unloaded control membrane while maintaining high sodium chloride rejection using brackish water containing no foulants as a feed source. Feed containing bovine serum albumin (BSA) and sodium alginate has been used to investigate the fouling performance of the membranes. Water flux is seen to decrease as the membranes foul with complete recovery upon washing with DI water through two fouling cycles. The fouling behavior of the membrane was also studied with the addition of zCNC.