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