FO is attracting worldwide attention as an emerging technology in field of power generation, water reuse, desalination, pharmaceuticals and food processing. Still a critical challenge of finding out suitable draw solute for FO persists. Therefore the current research focuses on synthesizing hydrophilic Magnetic Nano Particles (HMNPs) and systematically investigating their potential as draw solute. HMNPs were synthesized using functional group Polyethyle glycol (PEG 400) and Polacrylic acid (PAA). These functional groups under different ratio with metal precursor react by one pot polyp and thermal decomposition method respectively to give different diameter HMNPs. In addition the effect of different size of synthesized HMNPs was investigated for their recovery under external magnetic field and reusability in FO performance. The physical properties and chemical compositions of the resultant MNPs are fully characterized. Transmission electron microscopy (TEM) analyses show the characteristics as spherical morphology with narrow size distribution, and a mean size from 9 to 32.5 nm for PEG and 8 to 30 for PAA coated HMNPs depending on the ratio of the functional group and metal precursor. The PEG and PAA layer on the MNPs is confirmed by Fourier transform infrared (FTIR) analysis and thermogravimetric analysis demonstrates a hydrophilic surface composition. The PEG and PAA coated HMNPs generate high osmotic pressures and exhibit good dispersibility in aqueous solutions. Water fluxes of >13 L m−2 h−1 are achieved across Hydration Technologies Inc. flat sheet membranes at a concentration of 0.05 M concentration of HMNPs using deionized water as the feed solution. The HMNPs can be easily recaptured from draw solutions by applying a external magnetic field and recycled back as draw solute in FO process. The MNPs remain active after nine runs of recycle but with a total water flux decrease of 5% in PEG and 3% with each successive recycled due to slight aggregation and reduced surface to volume ratio was observed. Results of present study have demonstrated that using PEG and PAA coated HMNPs can viewed as a promising and potential draw solutes in the FO process.
- forward osmosis
- hydrophilic magnetic nano particle
- water reuse
- First received 1 May 2015.
- Accepted in revised form 17 August 2015.
- © IWA Publishing 2015