Molecular-level mechanisms in amide-based porous polymers for selective copper adsorption: A DFT study with environmental applications.

The deployment of element-specific stabilizers is pivotal for the precision remediation of contaminated soils. A novel amide-containing porous polymer (APOP) has been designed based on coordination chemistry theories. An impressive adsorption capacity of 92.8 mg g-1 (1.461 mmol g-1) at pH 6 has been achieved, showcasing APOP's exceptional performance. Notably, APOP exhibits a pronounced selectivity for Cu ions, boasting a remarkable Kd of 883 mL g-1 in a 50 mg L-1 multi-metal ion matrix. This selectivity markedly surpasses its affinity for any other metals, highlighting APOP's superior targeting ability for Cu ions. Density functional theory calculations reveal an innovative adsorption mechanism grounded in frontier orbital theory, suggesting that the close alignment of frontier orbital energy levels between Cu ions and APOP significantly contributes to APOP's high selectivity, a finding that warrants further investigation. Pot-and-elution experiments showed that APOP effectively reduced the leaching risk of Cu in an eco-friendly manner. This study provides fresh perspectives and strategic guidance for the molecular-level design of selective adsorbents, which aims to effectively mitigate the leaching risk of heavy metals and preventing groundwater contamination.