A porous andesite-stabilized nZVI (CMC) composite for efficiently removing Cd(II) and Pb(II) from electroplating wastewater.

The treatment of electroplating wastewater containing toxic Pb(II) and Cd(II) requires efficient adsorbents. To address the agglomeration and oxidation of nanoscale zero-valent iron (nZVI), we developed a novel composite, AM-nZVI-CMC, by stabilizing nZVI with carboxymethyl cellulose (CMC) on a porous acid-modified andesite matrix (AM). Characterization confirmed uniform dispersion of nZVI particles (23-72 nm). Batch adsorption was rapid and followed the Langmuir model, with maximum capacities of 62.37 mg g-1 for Pb(II) and 57.04 mg g-1 for Cd(II). It outperformed commercial activated carbon in real wastewater, achieving >82% removal for both metals, and retained >85% capacity after 5-week storage. Column tests and cost analysis support its practical potential. This work presents AM-nZVI-CMC as a dual-stabilized, cost-effective composite that integrates physical confinement and chemical protection to overcome the inherent limitations of nZVI. Its superior performance in real wastewater, excellent storage stability, and favorable economics highlight its potential as a practical alternative for heavy metal remediation.