Selective separation of polyphenols with a novel azo porous organic polymer: Ultrahigh adsorption capacity and superfast adsorption rate

Abstract

For the first time, a novel porous organic polymer (POP), namely Cin-POP, was constructed under normal temperature and pressure using less toxic basic fuchsin and natural cinnamic acid. Cin-POP was synthesized through the diazo-coupling reaction between the diazonium salts of basic fuchsin and cinnamic acid. The FT-IR spectra and XPS analysis prove the successful construction of the Cin-POP, and the BET analysis demonstrates the high-surface-area (166.42–202.56 m² g⁻¹) and suitable pore sizes (11.00–18.63 nm). Owing to the advantages of porous structures, abundant aromatic groups, good thermal stability, and good dispersity, Cin-POP exhibits remarkable adsorption rates and capacities towards polyphenols, including procyanidine and rutin. Especially for procyanidine, the extraction efficiency can arrive at nearly 98.1 % after 2.5 min adsorption, and the pseudo-second-order rate constant (k₂) of Cin-POP is 0.0257 g mg⁻¹ min⁻¹. The maximum adsorption capacities of Cin-POP towards procyanidine and rutin are 2500.00 mg g⁻¹ and 1814.83 mg g⁻¹, outpacing all reported adsorbents. In addition, Cin-POP can selectively adsorb polyphenol among the mixtures of polyphenols and alkaloids. More importantly, Cin-POP can be used for polyphenols separation from complex cinnamon extract. All the above advantages make Cin-POP comparable porous adsorbent for polyphenol separation.