Desalination of saline water via forward osmosis using magnetic nanoparticles covalently functionalized with citrate ions as osmotic agent.

Forward osmosis is an emerging membrane technology in water desalination. In this study, desalination of saline water via forward osmosis was investigated using a new magnetic osmotic agent. For this purpose, FeO nanoparticles covalently functionalised with tri-sodium citrate was synthesised and characterised. The structural examinations revealed that the sodium citrate had been immobilised onto the magnetic nanoparticles. The highest water flux was obtained 17.1 L Mh (LMH) per 80 g L osmotic agent solution against deionised water, while the ratio of salt flux to water flux was very low (0.088 g L). The osmotic solution was evaluated for saline water desalination using different concentrations of sodium chloride (NaCl) as feed solutions. The average water fluxes of 6.2, 4.5, and 2.7 LMH was obtained for 0.1, 0.2, and 0.5 M salt solutions, respectively. The magnetic osmotic agent was separated by a magnet and re-used for several times without considerable decrease in the water flux.