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Highly hydrophilic magnetic nanoparticles have been molecularly designed. For the first time, the application of highly water-soluble magnetic nanoparticles as novel draw solutes in forward osmosis (FO) was systematically investigated. Magnetic nanoparticles functionalized by various groups were synthesized to explore the correlation between the surface chemistry of magnetic nanoparticles and the achieved osmolality. We verified that magnetic nanoparticles capped with polyacrylic acid can yield the highest driving force and subsequently highest water flux among others. The used magnetic nanoparticles can be captured by the magnetic field and recycled back into the stream as draw solutes in the FO process. In addition, magnetic nanoparticles of different diameters were also synthesized to study the effect of particles size on FO performance. We demonstrate that the engineering of surface hydrophilicity and magnetic nanoparticle size is crucial in the application of nanoparticles as draw solutes in FO. It is believed that magnetic nanoparticles will soon be extensively used in this area.

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Thermosensitive superparamagnetic nanoparticles were synthesized by a one-step thermal decomposition method and successfully recycled as a 'smart' draw solute in forward osmosis processes for water reuse without losing performance efficiency.

Draw solutions of surface-dissociated nanoparticles in forward osmosis (FO) processes and their regeneration through an integrated electric field-nanofiltration system for water reclamation were explored for the first time. Nanoparticles of 20 nm in diameter were functionalized with different surface chemistries to systematically investigate the effects on the FO performance. Experimental results showed that the draw solutions of surface-dissociated nanoparticle prepared with alkalis exhibited higher osmotic driving forces. Compared to salt base draw solutes, the advantage of surface-dissociated nanoparticle draw solutes exhibits no reverse flux across the FO membrane. The diluted draw solution of surface-dissociated nanoparticles can be readily recovered via an integrated electric field and nanofiltration system with sustainable regeneration efficiency. Our preliminary results suggest the potential of surface-dissociated nanoparticles as draw solutes in FO for water reuse.