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Cellulose nanocrystals (CNCs) are biodegradable nanoparticles with a high aspect ratio and abundant surface hydroxyl groups resulting in negatively charged hydrophilic surfaces that make them an ideal candidate to be incorporated in thin‐film nanocomposite (TFN) membranes. In this study, we modified the CNCs via acetylation (ACNCs) to reduce their hydrophilicity and via reaction with L‐cysteine (CysCNCs) to impart them with functionality that promoted their interaction with the trimesoyl chloride organic monomer used in the preparation of the poly(amide) layer of the TFN membranes. These modifications allowed us to question in which monomer solution the nanoparticles should be dispersed. Addition of the unmodified CNCs in either the aqueous or organic monomer solution showed little difference in membrane performance. However, the addition of either the ACNCs or the CysCNCs to the organic monomer solution led to a significant increase in membrane performance in reverse osmosis (RO) and nanofiltration (NF) systems compared to their addition to the aqueous monomer solution. In addition, the CysCNCs exhibited performance very near the upper‐bound line for RO and NF. [ABSTRACT FROM AUTHOR]

The application of nanofiltration (NF) membranes in the forward osmosis (FO) process to remove heavy metal ions from wastewater is an emerging concept. Unlike NF, FO does not require an external driving force. Although the product, a dilute draw solution, must further be processed by NF to produce pure water and reconcentrate a draw solution, the feed to that NF process is "clean", which minimizes membrane fouling. This paper examines the role of Cu2+ and Pb2+ in the feed solution on the water and the reverse solute fluxes in FO process using novel thin film nanocomposite (TFN) NF membranes. The TFN membranes were fabricated by in situ interfacial polymerization of piperazine (PIP) and 1,3,5-benzenetricarbonyl trichloride (TMC) containing different amounts of dispersed halloysite nanotubes (HNTs) nanoparticles functionalized with the first generation of poly(amidoamine) (PAMAM) dendrimers. The presence of Cu2+ and Pb2+ in the feed solution decreased the reverse flux of MgCl2 by at least 2.5 times compared to the experiments with pure water as a feed. Simultaneously, the water flux also increased. The corresponding rejections of Cu2+ and Pb2+ in the FO process ranged from 94.5% to 98.1%. [ABSTRACT FROM AUTHOR]