Using Deep Eutectic Solvent for Conjugation of Fe3O4 Nanoparticles onto Graphene Oxide for Water Pollutant Removal

Deep eutectic solvents (DESs) have emerged as a substitute for ionic liquids with lower cost and enhanced biodegradability. The most common class of DES refers to a mixture of a quaternary ammonium or phosphonium salt and a hydrogen bond donor (e.g., carboxylic acid) with a melting point lower than that of individual components. DESs have recently shown promise for surface modification of graphene oxide (GO) nanosheets with different functional groups. We hypothesize that such surface functionalization of GO (and other carbon nanomaterials) with DESs can provide a new route to conjugate metallic nanoparticles onto GO surfaces (and similar). Here, we used a typical DES, based on choline chloride and urea, for the conjugation of presynthesized Fe₃O₄ nanoparticles onto GO nanosheets at different GO:Fe₃O₄ ratios. Physicochemical characterization not only confirmed the ability of DES to prepare DES/GO-Fe₃O₄ nanohybrids successfully, but also evidenced the influence of DES on the homogeneity and size distribution of Fe₃O₄ nanoparticles in these nanohybrids. DES/GO-Fe₃O₄ nanohybrids can perform better than both GO and Fe₃O₄ as adsorbents for organic dyes (methylene blue, MB) and heavy metals (Lead (II)). However, depending on the contaminant type, the contaminant removal performance varied differently for DES/GO-Fe₃O₄ nanohybrids with different ratios.