Surface modification on a hyper-cross-linked polymeric adsorbent by multiple phenolic hydroxyl groups to be used as a specific adsorbent for adsorptive removal of p-nitroaniline from aqueous solution.

A hyper-cross-linked polymeric adsorbent functionalized with multiple phenolic hydroxyl groups HJ-03 was prepared in this study and its adsorptive characteristics for p-nitroaniline from aqueous solution were studied as compared with Amberlite XAD-4. The adsorption of p-nitroaniline was sensitive to the solution pH and the maximum adsorption capacity was observed at pH of 3.5. The adsorption kinetics obeyed the pseudo-second-order rate equation and the adsorption isotherms could be correlated to Langmuir isotherm model. The adsorption enthalpy, adsorption free energy, and adsorption entropy were calculated to be negative and the adsorption was mainly driven by enthalpy change. The polarity matching between HJ-03 resin and p-nitroaniline, the pore structure of HJ-03, and the size matching between the pore diameter of HJ-03 and the molecular size of p-nitroaniline brought the larger adsorption capacity and higher adsorption affinity.