Porous Covalent Organic Gels: Design, Synthesis and Fluoroquinolones Adsorption

We report the design and synthesis of three highly stable and porous covalent organic gels (H(C)OGs) based on C-3-symmetric benzene-1,3,5-tricarbohydrazides. The resultant H(C)OGs beared excellent adsorption properties and represented good reusability towards fluoroquinolones from aqueous solutions. The external adsorption behavior as well as internal mechanisms were both discussed. Using kinetic and isotherm analysis, we found that the adsorption processes of the three H(C)OGs keep to the pseudo-second order kinetic model and abide by the Langmuir isotherm model. Furthermore, the adsorption efficiency and maximum adsorption capacity were demonstrated to be as a result of the internal mechanisms involving proper poriness, electrostatic interactivity, hydrophobic interaction, pi-pi stacking/interactions and hydrogen bonding. The work thus pays a new way for the preparation of novel porous materials for removing fluoroquinolones from wastewater.