Adsorptive removal of emerging contaminants from water using superparamagnetic Fe3O4 nanoparticles bearing aminated β-cyclodextrin

Abstract

Concern is growing over the contamination of the aquatic environment with pharmaceutically active compounds (PhACs) and endocrine disrupting compounds (EDCs) because of their adverse effects on health and environment. In this study, the removal of two PhACs, naproxen and carbamazepine and one EDC, bisphenol A from aqueous solutions was examined by batch adsorption experiments onto 6-Deoxy-6-ethylenediamino-β-cyclodextrin (β-CDen) grafted thiodiglycolic acid (TDGA) modified magnetic nanoparticles (CDen-MNPs).β-CDen being grafted on TDGA-coated Fe3O4 nanoparticle contributed to an enhancement of adsorption capacities because of the inclusion abilities of its hydrophobic cavity with organic contaminants through host–guest interactions. The effect of solution pH on adsorption of contaminants was investigated over the range of pH 3–11. Results show that physicochemical properties of each organic pollutant (pKa, hydrophobicity etc.) were important factors in adsorption process. Bisphenol A (logKow 3.3) was least adsorbed, whereas carbamazepine (logKow 2.45) was most adsorbable. The interactions of these pollutants with MNPs bearing cyclodextrin moieties followed the well-established Freundlich isotherm model and pseudo-second-order kinetic model. Kinetic studies also indicate that molecular size and structure of the contaminant influenced the rate of adsorption process. Furthermore, residue of inclusion complexes among the contaminants and β-CDen were scrutinized using FTIR spectroscopy and van der Waal's interaction was found to be dominant. Our results suggest that CDen-MNPs would provide a new platform for removing of PhACs and EDCs using magnetic separation technique.