Rational design of ionic covalent organic frameworks for PPCPs elimination: Insights into ibuprofen adsorption performance and mechanism

Abstract

Over the last few years, non-steroidal drugs (including ibuprofen (IBP)) have been used extensively due to the impacts of COVID-19, with the resulting environmental contamination attracting the attention of researchers. For this study, an ionic covalent organic framework (iCOF), synthesized from 1,2,4,5-tetrakis (4-formylphenyl) benzene (TFPB) and 1,3-diaminoguanidine hydrochloride (DgCl) under hydrothermal conditions, was employed for the effective elimination of non-steroidal anti-inflammatory drugs (NSAIDs) from aqueous media. COFs are relatively ordered spherical structures with excellent adsorption capacities for NSAIDs (IBP, diclofenac (DCF), and indomethacin (IDM)) with a removal rate of more than 99%. The adsorption kinetics and isotherm experiments of the COFs were investigated with IBP as a target contaminant, which revealed that its adsorption attained equilibrium within 120 min. Further, increased temperatures promoted the adsorption of IBP, where its maximum adsorption at 45 °C was calculated by the Langmuir isotherm model up to 434.78 mg·g-1. In addition, different pH, ionic influences, and repeated cycling experiments also confirmed the practical applicability of the COFs. Finally, it was demonstrated that the adsorption kinetics of IBP by TFPB-DgCl-COF could be explained by electrostatic and π-π interactions.