Synthesis of alkyl-functionalized magnetic for fluoroquinolones removal: Adsorption performance and mechanism studies in single and binary systems

The functionalized mesoporous silica (FMS) and core-shell magnetic functionalized mesoporous silica (MMS) were synthesized on the basis of unfunctionalized mesoporous silica (UMS) via alkyl modification and one-pot reaction. Its adsorption properties to enrofloxacin (ENR), pefloxacin (PEF) and ciprofloxacin (CIP) were systematically investigated in single and binary systems. The results indicated the adsorption performance of MMS is five times higher than UMS. Batch adsorption experiments demonstrated the MMS had a higher adsorption capacity and adsorption efficiency for FQs, with the maximum adsorption capacities of 201.52 mg g -1 for CIP, 275.46 mg g -1 for PEF and 286.35 mg g -1 for ENR. Meanwhile, over 80% and 90% removals were achieved within 5 min and 10 min. Experiment results also presented that: MMS was able to reach the maximum adsorption capacity around pH 7.0 and maintain high adsorption capacity at a high concentration of humic acid. Besides, MMS showed the selective adsorption to three FQs in the binary adsorption experiments. The reusability experiment suggested the MMS possess excellent stability. H-bonding, electrostatic interaction and hydrophobic interaction were the main driving force between three FQs and MMS. Moreover, the adsorbent can be readily separated from water solution by an external magnet. These obtained results could be used for adsorbent design in considering of the properties of the adsorbates and the reuse of adsorbents.