Dynamic Adsorption of Low-Concentration Formaldehyde Using One-Step Synthesized Amino-Functionalized Hyper-Cross-Linked Ionic Copolymers.

Formaldehyde (FA) emissions seriously influence the environment and human health, while traditional adsorbents are restricted by low capacity and poor selectivity. To address these limitations, amino-functional hyper-cross-linked copolymer ionic compounds (HPIL-Cl-Xs) were designed and synthesized through a one-step hyper-cross-linking and quaternization reaction involving benzimidazole, dichloro-p-xylene, and functional monomers. These polymers provide an ionic environment, active adsorption sites, and a microporous structure, offering abundant adsorption sites. The synthesis parameters were studied to optimize the preparation conditions. Under conditions of 8.6 ppm and WHSV of 54,000 h-1, the equilibrium adsorption capacity of HPIL-Cl-Phe (phenylalanine) reached 11.3 mg/g with a partitioning coefficient (PC) of 0.44 mol·kg-1·Pa-1, surpassing that of conventional adsorbents. The impacts of the adsorption temperature, WHSV, and relative humidity on adsorption were explored, confirming the adaptability of HPIL-Cl-Xs to various environmental conditions. DFT calculations, XPS, and FT-IR confirmed the existence of hydrogen bond interactions and nucleophilic addition reactions. HPIL-Cl-Phe demonstrated an excellent cycling performance with stable adsorption over multiple cycles.