In this work, we develop and demonstrate highly stable organic-coated engineered superparamagnetic iron oxide nanoparticles (IONPs), which provide effective osmotic pressure without aggregation, reverse diffusion, or membrane blocking (by nanoparticles) for osmotically driven membrane systems, considering both forward osmosis (FO) and pressure-retarded osmosis (PRO). For this, we synthesized highly water stable, monodisperse 12 nm IONPs with a rational series of water stabilizing surface coatings, including sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and polyethylene glycol (PEG). We then compared the library of surface functionalized IONPs as draw solutes for osmotic pressure-driven membrane processes. As synthesized, surface (organic) coatings are compact, thin, and can have very similar surface charge as the membrane itself, which results in effective osmotic pressure in forward osmosis (FO) mode configuration. To increase the osmotic pressure further, on a per mass basis, we synthesized and demonstrated novel hollow IONPs with identical surface coatings. Finally, water flux was further enhanced for stable particle systems using an oscillating magnetic field, thus physically altering concentration gradients, as a function of particle magnetic properties.

在这项工作中，我们开发并演示了高度稳定的有机涂层工程超顺磁性氧化铁纳米颗粒（IONPs），考虑到正向渗透，可为渗透驱动的膜系统提供有效的渗透压而不会发生聚集，反向扩散或膜被纳米颗粒阻塞的情况。 （FO）和压力延迟渗透（PRO）。为此，我们合成了高度水稳定性的单分散12 nm IONP，并具有一系列合理的水稳定表面涂层，包括十二烷基硫酸钠（SDS），十六烷基三甲基溴化铵（CTAB）和聚乙二醇（PEG）。然后，我们比较了表面功能化IONPs库作为渗透压驱动膜过程的吸引溶质。合成后，表面（有机）涂层致密，薄，并具有与膜本身非常相似的表面电荷，从而在正向渗透（FO）模式配置下产生有效的渗透压。为了进一步提高渗透压，我们以质量为基础合成并演示了具有相同表面涂层的新型中空IONP。最后，对于稳定的粒子系统，使用振荡磁场进一步提高了水通量，从而根据粒子磁性能物理改变了浓度梯度。