Fine-tuning the architecture of loose nanofiltration membrane for improved water flux, dye rejection and dye/salt selective separation

Applying Transition-State Theory to Explore Transport and Selectivity in Salt-Rejecting Membranes: A Critical Review

“…Reverse osmosis (RO) and nanofiltration (NF) have been the dominant processes for water desalination and advanced purification processes for many years. , The key component in these processes is a dense polymeric (commonly polyamide) membrane, possessing free-volume elements (or voids) in the size range of 0.1–2 nm that facilitate the separation of different ionic and molecular species . Because of their smaller size and neutral charge, water molecules permeate through the membrane faster than ions, allowing for excellent water-salt selectivity. , Size and charge effects also play a role in ion–ion selectivity, which is mostly exploited for water softening and sulfate removal due to the prominent differences between monovalent and divalent ions. − Other, more complex transport mechanisms can promote selectivity between akin species such as two monovalent anions, which can be beneficial for some applications (e.g., removing the excess of nitrate or fluoride from drinking water while keeping the unharmful chloride in the water). − Elucidating such molecular-level mechanisms is the focus of current research efforts, which are a key step toward the design of single-species selective membranes that can enhance the sustainability of current processes and expand the use of NF and RO membranes to applications beyond water treatment (e.g., resource recovery, energy devices, and sensing). ,− …”

2‐(N‐3‐Sulfopropyl‐N,N‐dimethyl ammonium)ethyl methacrylate modified graphene oxide embedded into cellulose acetate ultrafiltration membranes for improved performance

“…The increase in average pore size after the addition of nanofillers in the membrane matrix was observed. 70 The membranes with the highest filler content for both types of membranes exhibited the highest water uptake and porosity. For the GO series, the observed porosity trend was UF-1 < UF-2 < UF-3 (at 0.5 wt% GO).…”

“…The process of membrane fouling is very complicated; fouling is induced by protein adsorption derived from the combination of electrostatic interaction, hydrogen bonding, hydrophobic impact and van der Waals forces. Attributed for an ideal membrane surface that is resistant to protein fouling are good hydrophilicity and reduced roughness, 70 receptors, 71 free from hydrogen bond donors, 72 and overall electric neutrality. 73 The zwitterionic polymer (pSBMA) grafted onto GO contains phosphatidylcholine, which was expected to contribute these mentioned properties to the membrane surface.…”

Interpenetrating polymer networks for desalination and water remediation: a comprehensive review of research trends and prospects

“…Most of the rejection operations result from a synergism of size sieving and electrostatic interactions. [55][56][57][58] More specically, charge-bearing contaminants are either adsorbed or repelled by the charged membrane surface and pores. The Donnan exclusion principle plays a major role in the case of charge-based separation mechanisms.…”