Synthesis of magnetic nanoparticles with covalently bonded polyacrylic acid for use as forward osmosis draw agents

Irena Ban*, Mihael Drofenik, Hermina Bukšek, Irena Petrinic, Claus Helix-Nielsen, Sabina Vohl, Sašo Gyergyek, Janja Stergar

*Corresponding author for this work

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Abstract

Multicoated magnetite (Fe3O4) magnetic nanoparticles (MNPs) with polyacrylic acid (PAA) as a terminal hydrophilic ligand were synthesized and examined for use as a draw solution (DS) agent in forward osmosis (FO). After coating superparamagnetic iron-oxide MNPs with (3-aminopropyl)triethoxysilane (APTES) the carboxyl groups of PAA were bound to APTES amino groups via the crosslinker 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) forming a peptide bond resulting in stable water-soluble particles (MNP@APTES@PAA) with a concentration-normalised osmotic pressure of 1.56 bar L g−1. The MNP@APTES@PAA solution was evaluated as a DS in two FO filtrations with deionized (DI) water as a feed solution (FS): one using freshly prepared MNP@APTES@PAA and one using magnetically recovered (re-concentrated) MNP@APTES@PAA. The resulting MNP@APTES@PAA nanocomposites exhibit good colloidal stability in aqueous solution with a concentration-normalized osmotic pressure of 1.56 bar L g−1. This is 12-fold higher than that in our previous studies of poly-sodium-acrylate coated MNPs and 3-fold higher than that of citric acid coated MNPs. The water recoveries of the two filtrations were 25.7% and 13.6%, respectively, after 2 h of FO filtration time resulting in a DS osmotic pressure of 2.5 bar with a concentration of 4.3 g L−1 and a DS osmotic pressure of 2.6 with a concentration of 3.7 g L−1 respectively.
Original languageEnglish
JournalEnvironmental Science: Water Research and Technology
Volume9
Issue number2
Pages (from-to)442-453
Number of pages12
ISSN2053-1400
DOIs
Publication statusPublished - 2023

Bibliographical note

This research was funded by the Slovenian National Agency (grant numbers P3-0036, P2-0006, P2-0089, J1-9169, and J3- 1762, L4-1843) and NEPWAT funded by the Novo Nordisk Foundation.

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