Preparation of superparamagnetic iron oxide nanoparticles and evaluation of their adsorption capacity toward carbamazepine and diatrizoate

Carbamazepine (CBZ) and diatrizoate (DTZ) are from the group of pharmaceutical and personal care products known to be persistent and non-biodegradable in wastewater treatment. Adsorptive removal of CBZ and DTZ using superparamagnetic iron oxide (magnetite, Fe3O4) nanoparticles (NPs), along with those coated with either methacrylic acid (MAA), Al (OH)(3), or SiO2 were evaluated. Transmission electron microscopy and scanning electron microscopy analyzes revealed that the NPs were about 10 nm in diameter. Fourier transform infrared analysis confirmed the presence of carboxyl group on MAA-coated NPs, and hydroxyl group on alumina-and silica-coated NPs. Results suggest that the major fraction of the drugs is adsorbed by the NPs in about 6-8 h. Maximum DTZ adsorption capacities (based on Freundlich isotherm) of MAA-, Al(OH)(3)-, and SiO2-coated NPs (112.46, 82.20, and 90.48 mg/g, respectively) were much higher than that of the uncoated NPs (66.17 mg/g). Based on batch adsorption studies, an optimal adsorption condition was proposed, i.e. CBZ and DTZ concentration of 100 mu g/L, 0.05 g of NPs, adjusted pH of 8, and exposure time of 7 h. At this condition, the maximum adsorption of CBZ was about 32.7, 47.3, 51.1, and 50.2% with uncoated, MAA-coated, Al(OH)(3)-coated, and SiO2-coated NPs, respectively. The equivalent removal for DTZ by the NPs was at 44.3, 52.8, 60.6, and 38.1%, respectively. Further desorption studies revealed that about 85.56 and 78.00% of adsorbed CBZ and DTZ can be readily released from Al(OH) 3- and MAA-coated NPs, respectively.