Enhancement mechanism behind the different adsorptive behaviors of nitro/amine modified hypercrosslinked resins towards phenols.

• A microporous polymeric resin St-DVB-Al and nitro/amine modified resins were prepared. • The novel adsorption trends to phenols were revealed and systemically discussed. • The adsorption isotherms and thermodynamic studies verified the adsorption trends. • The DFT model explained the interaction forces in the adsorption processes. A hypercrosslinked resin, named St-DVB-Al, was prepared by optimizing the conditions of the Friedel–Crafts reaction. The nitro and amine groups were further introduced into the skeleton to prepare the composite functional resins St-DVB-nitro and St-DVB-amine. The adsorption capacity of the modified resins for phenolic compounds reached to 412.9 mg/g, which were 16.4–47.7% higher than the commercial resin H103 with similar physical structure. For the p-nitrophenol and p-hydroxybenzoic acid, the adsorption capacity trends were St-DVB-amine > St-DVB-Al > St-DVB-nitro, but for the hydroquinone was St-DVB-nitro > St-DVB-amine > St-DVB-Al. The reason St-DVB-nitro exhibited efficient adsorption for hydroquinone was that the electron-acceptor group enhanced the synergistic conjugation with the electron-donating compound. The introduction of the electron-donor group in St-DVB-amine enhanced the synergistic conjugation with electron-acceptor compounds as well as the hydrogen bonding and acid-base interaction, thus exhibiting highly efficient adsorption for p-nitrophenol and p-hydroxybenzoic acid. The DFT model was used to calculate the ΔE values of St-DVB-nitro, St-DVB-amine and St-DVB-Al with three adsorbates, and the results were consistent with the adsorption trends. Relationship between adsorption capacity and adsorption behavior was clarified by a quantitative perspective. [ABSTRACT FROM AUTHOR]