Hierarchical porous hyper-cross-linked polymers modified with phenolic hydroxyl groups and their efficient adsorption of aniline from aqueous solution

Herein two hierarchical porous hyper-cross-linked polymers modified with phenolic hydroxyl (OH) groups were synthesized and their adsorption was comparatively evaluated using aniline as the adsorbate. The results reveal that the phenolic OH groups are helpful for the equilibrium adsorption due to the increased polar matching by formation of acid-base complex and hydrogen bonding, and the hierarchical porosity is favorable for the kinetic adsorption because the three dimensional continuous mesopores facilitate the rapid diffusion of aniline. The original aniline solution is optimum for the adsorption and the molecular state of aniline is preferable. The maximum equilibrium capacity is predicted to be 184.8 mg/g by the Langmuir model, and the enthalpy change, Gibbs free energy change, and entropy change are calculated to be negative. The adsorption can reach equilibrium within 60 min, the kinetic data obey the pseudo-second-order rate equation and the first step of the adsorption is mainly controlled by the intra-particle diffusion model.