Mechanistic insights into heavy metal ion adsorption by 3-aminophenol-formaldehyde polymer adsorbents

Heavy metal pollution in water poses severe threats to ecosystems and human health, demanding urgent development of efficient and sustainable adsorbents. Herein, we report a novel amino-functionalized phenolic resin (APF) synthesized via a facile self-assembly strategy using 3-aminophenol and formaldehyde. This approach eliminates the need for toxic crosslinkers or complex post-modification steps, offering a green and scalable route for nanoscale polymer fabrication. The APF particles were engineered with controlled amino group density and hierarchical porosity through optimizing monomer ratios, achieving abundant active sites for multi-metal interactions. The APF adsorbent exhibits exceptional adsorption capacities for both cationic and anionic heavy metals, notably achieving 297.75 mg·g −1 for Cd 2+ – surpassing conventional clay composites and rivaling advanced MOFs. Its multifunctional groups (–NH 2 , –OH) enable synergistic mechanisms: (1) electrostatic attraction for Cr 6+ oxyanions at low pH, (2) chelation-dominated Cd 2+ capture via amino coordination, and (3) ion exchange for Pb 2+ /As 3+ . This work advances the design of cost-effective, multi-mechanistic adsorbents for comprehensive heavy metal remediation.