(473e) Investigations of Using Highly Water-Soluble Magnetic Nanoparticles as Novel Draw Solutes in Forward Osmosis

Water scarcity is gradually emerging as a worldwide problem due to accelerating population growth and environmental pollution. More and more regions are considered water-poor and face associated problems of food production and public health issues. Demands for clean water impel an emphasis on research in clean water reuse to avert a potential disaster. Forward Osmosis (FO) is an energy-efficient technology which utilizes the osmotic pressure difference between two aqueous solutions partitioned by a semi-permeable membrane as the driving force instead of hydraulic pressure. However, one of the challenges of FO still lie in the readily separable draw solutes of high osmotic pressures.

Superparamagnetic nanoparticles, which can be easily collected and separated from water by means of magnetic field, shall be considered as the draw solute in FO, assuming high osmotic pressures can be induced by magnetic nanoparticles or some other means, which comply with the criteria of draw solute in FO, including (1) high osmolality to generate high osmotic pressures, and (2) easy and efficient separation from water.

For the first time, the application of highly hydrophilic magnetic nanoparticles as draw solutes in forward osmosis (FO) was systematically investigated. Functionalized magnetic nanoparticles were synthesized to explore the correlation between surface chemistry of magnetic nanoparticles and the achieved FO performance. 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. It is demonstrated that the engineering of surface hydrophilicity and magnetic nanoparticle size are both crucial in their application as draw solutes in FO. It is believed that magnetic nanoparticles will soon find great use in this area.