Effective removal of two aqueous NASIDs by magnetic three-dimensional hollow Co-Ni LDH composite

Non-steroidal anti-inflammatory drugs (NSAIDs) have gained significant attention as emerging pollutants and are increasingly detected in aquatic environments. Therefore, it is imperative to investigate the efficient removal of NSAIDs from water systems. In this study, a magnetic LDH with three-dimensional hollow structure (Fe3O4@ZIF-67@Co-Ni LDH) was synthesized using ZIF-67 as a template for the removal of carprofen (CPF) and flurbiprofen (FLU) from water environments. The adsorption process of CPF and FLU on Fe3O4@ZIF-67@Co-Ni LDH and the competitive adsorption between these two NSAIDs were investigated. The adsorption mechanism was explored by experimental analysis and theoretical calculation. Results demonstrated that the pseudo-second-order kinetic model and Liu isotherm model can better fit the kinetic and isotherm data, and according to the thermodynamic data analysis, the adsorption process was exothermic, spontaneous and stable. The adsorption capacity of CPF and FLU on Fe3O4@ZIF-67@Co-Ni LDH can reach 856.2 mg/g and 797.5 mg/g. Fe3O4@ZIF-67@Co-Ni LDH exhibited high adsorption capacity for CPF and FLU in actual environment water, with stronger affinity towards CPF when both NSAIDs coexisted simultaneously. The three-dimensional hollow structure enhanced the adsorption capacity of Fe3O4@ZIF-67@Co-Ni LDH, making it a promising adsorbent for NSAIDs.