A Simple Scalable Route for the Production of Magnetic Nanomaterials and their Application in Wastewater Remediation

Abstract

Superparamagnetic Iron Oxide Nanoparticles (SPIONs) have found extensive applications in diverse fields that include biomedicine, water remediation, and drug delivery. These applications require the development of synthetic protocols and methods that can produce SPIONs with precisely controlled size and shape, with the added caveat of being scalable. A one-pot thermal decomposition route that avoids the separate preparation and purification of precursor complexes and, consequently, is easily scalable has been explored. Minor modifications, changing the reaction temperature, or addition of oleyl alcohol or sodium oleate along with oleic acid, allow for particle dimensions (5-20 nm) and morphology, spheroid/ cuboid, to be controlled. Additionally, the particles are readily transferred from the crude reaction media to an aqueous phase using nitrilotriacetic acid (NTA) as a phase transfer agent. The modified thermal decomposition route has been extended for the preparation of transition metal ferrite nanoparticles while still retaining the ease of the original method. Similar to ferrites, transition metal and metal oxide nanoparticles are also an important class of materials and have found immense importance across a wide range of applications. Size and shape-tunable synthesis of metal/metal oxide nanoparticles could be achieved following the modified thermal decomposition route.

Subsequently, pH-induced charge reversal was leveraged to facilitate the selective adsorption of target analytes possessing a charge opposite to that of the NTA@SPIONs. The NTA@SPIONs, along with the adsorbed contaminants, can then be separated from the aqueous dispersion utilizing a simple magnetic field, thereby yielding purified, decontaminated water. Illustrative instances of both cationic and anionic contaminants, encompassing toxic synthetic dyes and heavy metal ions, were effectively sequestered from water employing the NTA@SPIONs.