Functionalized Magnetic Nanocomposites for Heavy Metal Removal: Branched versus Linear Phosphonated Polyetheramines

The development of efficient and magnetically recoverable nanoadsorbents is critical for sustainable heavy metal remediation. In this study, we coated superparamagnetic iron oxide nanoparticles (SPIONs) with phosphonated polyetheramines synthesized from two different polymers: linear EDR-176 (denoted as PE176) and branched T-403 (denoted as PT403). The resulting nanocomposites are referred to as SPIONs-PE176 and SPIONs-PT403, respectively. Our characterization confirmed successful coating, improved colloidal stability, and adjustable surface properties. Adsorption experiments targeting Cu2+, Ni2+, and Co2+ revealed distinct metal-specific trends SPIONs-PE176 removed Cu2+ more effectively at low concentrations due to stronger surface charge interactions, while SPIONs-PT403 achieved higher loading capacity and broader uptake of Ni2+ and Co2+ due to its denser structure. Kinetic, isotherm, and thermodynamic analyses confirmed that polymer architecture governs adsorption mechanisms and energetics. We demonstrate that tuning polymer structure provides a versatile strategy to optimize SPION-based nanocomposites for targeted water treatment.