triacetate cta membrane produced by hydration technology innovations hti was used as a membrane water flux when using the nanoparticles according to the present disclosure was measured under conditions that the draw solution and a capacity of reservoir were 500 ml respectively a flow rate was 8 5 m sec and 10 hour operation was performed the measurement result was 8 lmh which was an excellent performance it was confirmed that the superparamagnetic nanoparticles were easily recoverable from the draw solution using a magnet after operation and recyclable by virtue of re dispersibility thereof dispersibility in salt water of superparamagnetic iron oxide nanoparticles having size of 7 06 nm in water and monodispersed distribution to estimate dispersibility of the nanoparticles under rigorous conditions using the nanoparticles produced in example 1 the following experiment was carried out salt water with the same saline concentration 3 5 as seawater was prepared the nanoparticles produced in example 1 were added to the salt water such that the concentration became 0 0065 m this solution was stirred for 1 hour and the nanoparticles were recovered by use of a magnet followed by two time washing and then dispersed in water hydrodynamic diameters of the nanoparticles dispersed in water were analyzed and the results were 8 1 u00b1 1 2 nm accordingly it was confirmed that no.