Adsorption Behavior of Polycyclic Aromatic Hydrocarbons on Zn-Based Coordination Cluster Zn5: Competition, Synergy, and Mechanism

In this work, adsorption behaviors of pyrene (PYR), fluoranthene (FLT), phenanthrene (PHE), and fluorene (FLU) on the coordination cluster [Zn5(H2Ln)6](NO3)4]·8H2O·2CH3OH (Zn5) were studied. The adsorption mechanism and spectrum analyses revealed that the synergistic effect of hydrophobic interaction, π–π stacking, and N–H···π interaction played a crucial role during the adsorption process. The maximum adsorption capacities of PYR, FLT, PHE, and FLU were 406.4, 399.7, 153.7, and 114.3 mg g–1, respectively, resulting from the Langmuir isotherm model. Quick removal of PYR and FLT was found in kinetic experiments with the adsorption equilibrium being reached within 1 min. Competitive adsorption indicated that the adsorption sites for PYR, FLT, PHE, and FLU on Zn5 were identical, and synergistic effects also existed in the adsorption process. Therefore, Zn5 has the potential to be used as an adsorbent in the field of wastewater treatment.