Polymer-Assisted Synthesis of Magnetic Fe3 O4 Nanomaterials for Efficient Heavy Metal Removal from Contaminated Water Systems

Abstract

The toxicity, non-biodegradability, bioaccumulation properties and persistence of toxic metal ions like Pb(II), Cd(II), Hg(II) and Cr(VI) have resulted in the emergence of heavy metal contamination in the aquatic environment as a major environmental and public 
health challenge. The traditional techniques of wastewater treatment, such as chemical precipitation, membrane filtration and ion exchange tend to be characterized by high cost of operation, sludge formation and low removal rate. Here, magnetic Fe 3 O 4 nanomaterials were fabricated with polymer (as aid) to create efficient and reusable nanoadsorbents in removing heavy metals in water systems that are contaminated. Synthesis incorporation of polymeric surface stabilizers was used to reduce agglomeration of the nanoparticles, enhance surface functionality, adsorption stability, and to increase the number of active sites to bind to the metal ions. The magnetic Fe₃O₄ nanomaterials were prepared employing a controlled co-precipitation technique in the existence of polymeric stabilizing agents. The produced nanocomposites were carefully characterized in X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface area, thermogravimetric (TGA), and vibrating sample magnetometry (VSM) to examine the crystallinity, morphology, functional groups, thermal stability, magnetic properties, and surface characteristics. Experiments of batch adsorption were conducted under different conditions of operation such as pH, contact time, dosage of adsorbent used and initial concentration of heavy metals. The produced polymer-assisted Fe₃O₄ nanomaterials had a high removal efficiency as well as high adsorption kinetics and adsorption rate towards toxic heavy metal ions. Solution pH and contact time were found to have a strong effect on adsorption process whereas magnetic recovery allowed the nanoadsorbents to be separated quickly upon treatment. The adsorption equilibrium data were highly compatible with the Langmuir isotherm model indicating that the adsorption process was monolayer, whereas kinetic studies indicated that the adsorption process was supported by the pseudo-second-order kinetic model, indicating that the interactions between the two were chemisorption-dominated. The magnetic polymer-functionalized Fe₃O₄ nanomaterials synthesized exhibited increased adsorption capacity, structural stability, reusability and magnetic separability relative to the bare Fe₃O₄ nanoparticles. This research emphasizes the environmental importance of sustainable polymer-assisted magnetic nanoadsorbents as the promising materials in the efficient wastewater treatment and the further in-house heavy metal recovery of industrial and environmental treatment systems.