Coordination-Driven Synthesis of Hierarchical Metal–Organic Network (MON) Particles for Efficient Cu(II) Removal: Structural Design-Characterization and Adsorption Performance

Abstract

Copper (Cu(II)) contamination in aquatic systems is a pressing environmental issue due to its high toxicity, bioaccumulation potential, and adverse effects on ecosystems and human health. Developing adsorbent materials with high capacity, structural stability, and tunable surface chemistry is essential for efficient water purification. In this study, hierarchical metal–organic network (MON) particles were synthesized via a coordination-driven polycondensation of polyphenols and formaldehyde, resulting in robust, fiber-like structures with well-defined micro- (~ 1.6 nm) and mesopores (~ 13.9 nm) and a high surface area of 212.58 m²/g. The hierarchical pore architecture enhances mass transfer and adsorption kinetics, enabling a maximum Cu(II) adsorption capacity of 417.21 mg/g at 301.15 K, following the pseudo-second-order kinetic model and Langmuir isotherm. Thermodynamic analysis revealed that adsorption is spontaneous and endothermic, indicating strong chemisorption interactions through oxygen-containing functional groups. These results demonstrate that coordination-driven self-assembly represents an effective strategy for designing high-performance adsorbents with controlled pore structures and superior metal-binding capabilities. Beyond Cu(II) removal, this approach holds significant potential for developing next-generation materials for advanced water treatment, environmental remediation, and sustainable resource recovery.