Assessment of pectin-coated magnetite nanoparticles in low-energy water desalination applications

Novel magnetite nanoparticles (NPs) modified with pectin coating were fabricated, characterized, and evaluated as potential draw solute in a forward osmosis (FO) process for water desalination applications. The prepared NPs had a spherical shape with an average diameter of 200 nm and saturation magnetization of 23.13 emu/g. Thermogravimetric analysis (TGA) and FTIR spectra elucidated the successful pectin coating on magnetite surface. The potential use of the fabricated NPs in water desalination was conducted via a newly developed lab-scale FO system. Deionized water, saline water (0.2, 0.5, and 1 g% NaCl solution), and real well water (TDS = 0.9 g%) were used as feed solutions. In all experiments, the water flux gradually decreased along with the extension of experimental time and NaCl rejection rate by the FO membrane was measured to be higher than 95%. Moreover, it was found that the pectin-coated magnetite NPs demonstrated to be able to draw clean water across the FO membrane from well water with a remarkable salt rejection of 97%. Thus, it is believed that the proposed FO system using pectin-coated magnetite NPs as draw solute can be a promising technique for desalination of well waters in an environmental-friendly and energy-saving manner.