Forward osmosis using highly water dispersible sodium alginate sulfate coated-Fe3O4 nanoparticles as innovative draw solution for water desalination

Abstract

The remarkable advancement of forward osmosis (FO) as a promising technology for water treatment encounter difficulties due to the synthesis and recovery of a suitable draw solution (DS). The easy recyclability of the draw solution and energy consumption are the critical issues in FO processes. In this work, we have introduced the magnetic core-hydrophilic shell nanoparticles as an efficient draw solute for FO processes. The surface of nanoparticles was modified with sodium alginate sulfate (SAS) as a biocompatible, low toxic and relatively low-cost hydrophilic material. In this regard, the dispersibility and stability of Fe3O4 nanoparticles in aqueous solution was enhanced. The average water flux of 0.06 g mL–1 Fe3O4@SiO2-SAS was determined as 12.8 and 8.5 L m–2 h–1 with a reverse solute flux of 1.48 and 0.23 g m–2 h–1 in PRO and FO modes, respectively. Concentrations of 0.05, 0.1 and 0.2 M NaCl have been used as feed solution to study the performance of the DS for desalination process. Moreover, the optimum DS was successfully used for treatment of a real wastewater. Eventually, the synthesized draw solution was recovered by a magnetic field and its reusability was tested. High stability and simple regeneration of DS decreases the cost of water production.