Precursor engineering of metal-organic frameworks derived carbon for high-capacity rutin adsorption

Efficient separation of bioactive flavonoids from complex plant matrices presents a substantial challenge for the pharmaceutical and nutraceutical industries, highlighting the necessity for adsorbents with improved capacity and selectivity. To tackle this issue, a precursor engineering strategy was developed to create high-performance adsorbents. Specifically, a Fe-doped ZIF-8 template was modified with hydrophilic polydopamine (PDA) or polyethyleneimine (PEI), followed by pyrolysis to yield three types of nitrogen-doped carbon materials (FeNC, FeNC-PDA, FeNC-PEI). These materials were thoroughly characterized using TEM, XRD, BET, FTIR, and XPS techniques. The hydrophilic modifications significantly enhanced the adsorption capacity for the model flavonoid rutin. Notably, the FeNC-PDA adsorbent achieved an impressive equilibrium capacity of 348.78 mg/g, which is 4–10 times higher than that of conventional macroporous resins and outperforms most advanced carbon-based adsorbents reported in the literature. Mechanistic analysis indicates that this remarkable performance is attributed to a synergistic interplay of hierarchical porosity, increased electrostatic interactions, multifaceted hydrogen bonding, and π–π stacking, all supported by nitrogen-enriched functional surfaces. This work not only presents a highly effective adsorbent for rutin purification but also introduces a versatile precursor modification strategy for the rational design of carbon-based materials tailored for polar bioactive compounds.