Fabrication of Core-Shell CMNP@PmPD Nanocomposite for Efficient As(V) Adsorption and Reduction

Here, we prepared novel carboxyl-functionalized Fe₃O₄ nanoparticles (CMNPs) coated with poly(m-phenylenediamine) (CMNP@PmPDs) without complicated premodification procedures. The CMNP@PmPDs show well-defined core-shell structures and combine both the facile separation properties of magnetic particles and the extraordinary adsorption performance of polymers. The CMNP@PmPDs were employed to investigate the influence of various environmental factors (initial pH, ionic strength, etc.) on the removal of As(V) through batch experiments. The CMNP@PmPDs display much better As(V) adsorption performance than the CMNPs, and the adsorption capacity is enhanced from 51.2 mg g^-1 to 95.2 mg g^-1. The CMNP@PmPDs exhibit high magnetization (∼46.7 emu g^-1), indicating their easy separation under an external magnetic field in practical applications. The major reaction pathway involving the reduction of As(V) to As(III) was identified by X-ray photoelectron spectroscopy (XPS) analysis. The removal mechanisms can be explained by the adsorption of As(V) on protonated imino and carboxyl groups via electrostatic attraction, which is then reduced to As(III) by amine groups. This study demonstrates the potential application of CMNP@PmPDs as a low-cost and effective remediation strategy for the removal of As(V) from wastewater.