Hyperbranched Polyglycerol Carboxylate-Coated Magnetic Nanoparticles as a Draw Solute in a Combined Forward Osmosis and Ultrafiltration Process

Hyperbranched polyglycerol carboxylate-coated magnetic nanoparticles (HPGC-MNPs) were evaluated as a draw solute in a combined forward osmosis (FO) and ultrafiltration process. After a one-step synthesis of hyperbranched polyglycerol-coated magnetic nanoparticles (HPG-MNPs), hyperbranched polyglycerol carboxylate chains were synthesized on the surfaces of the nanoparticles by the reaction of surface hydroxyl groups on the HPG with sodium chloroacetate. The resulting HPGC-MNPs, with an average diameter of 29.5 nm, displayed excellent solubility in water and no precipitation up to a concentration of 500 g/L. A draw solution of HPGC-MNPs exhibited a higher osmotic pressure and water flux during the FO test than succinate-functionalized polyglycerolcoated magnetic nanoparticles (SHPG-MNPs) due to the high ionization capacity of the HPGCMNPs. Moreover, the HPGC-MNPs did not show any reverse draw solute leakage during the FO process, and the water flux was nearly unchanged even after several regeneration cycles of the HPGC-MNP draw solute using an UF process. The HPGC-MNPs demonstrate strong potential for use as a draw solute in FO processes.