Synthesis and characterization of a high-performance supramolecular polymer for the adsorption of anionic dyes and iodine: a comprehensive study

To address the challenge of an increasingly polluted environment, this study developed an efficient adsorbent capable of removing anionic pollutants. Pillar[5]arene (P5) was synthesized and cross-linked with polyethyleneimine (PEI) to form PEI-P5, a non-porous adsorbent. Compared with porous materials, non-porous adsorbents exhibit unique advantages in selective adsorption. The synthesized PEI-P5 contains numerous amino groups and amido groups, and exhibits excellent selectivity for the adsorption of anionic pollutants. It exhibited superior adsorption performance for anionic dyes, with a 98.7 % removal rate for eosin B and a maximum adsorption capacity of 633.98 mg/g. It also demonstrated robust adsorption capabilities for I₂/KI, reaching a peak adsorption capacity of 1622.80 mg/g, and for iodine vapor, with an adsorption capacity of 5000 mg/g. Combined analysis through Independent Gradient Model based on Hirshfeld partition (IGMH) and Fourier-Transform Infrared (FTIR) spectroscopy revealed that the predominant adsorption mechanisms involve electrostatic interactions and π-π stacking interactions, while van der Waals forces, hydrogen bonds, and CH···I interactions contribute synergistically to the adsorption system. Remarkably, PEI-P5 maintained >90 % removal efficiency under simulated real-world conditions and effectively adsorbed trace pollutants (50 ppb to 1 ppm), highlighting its potential for environmental remediation.