Enhanced water flux using uncoated magnetic nanoparticles as a draw solution in forward osmosis desalination

Pure uncoated magnetic nanoparticles (MNPs) were synthesized and studied as a potential draw solution (DS) in forward osmosis (FO) desalination process. Saturation magnetization was found to be 3.79 emu/g and the formation of Fe3O4 MNPs was confirmed by Fourier transform infrared and X-ray diffraction spectra. The osmotic potential of Fe3O4 MNPs was evaluated using a bench-scale crossflow FO unit. The feed solution (FS) of deionized water and NaCl solutions of different salinities (0.5, 1, and 2 g% NaCl) were evaluated. The water flux was found to decrease with the increase in water salinity of the FS by 62%, 78%, and 87% for the 2.5 g% MNPs, respectively. Furthermore, the Fe3O4 MNPs concentration (2.5 and 5 g%) was found to have a substantial impact on water flux with a three-fold increase in the pure water flux for the higher concentration. Results confirmed that the concentration of both FS (NaCl) and DS (MNPs) have a considerable effect on the produced pure water flux. This research demonstrated that the proposed uncoated Fe3O4 MNPs can be used as a potential draw solution for water desalination.