Preparation and characterization of NiFe_2O_4/activated carbon composite as potential magnetic adsorbent for removal of ibuprofen and ketoprofen Pharmaceuticals from aqueous solutions

摘要

NiFe2O4/activated carbon magnetic composite (NiAC) was produced by hydrothermal method, characterized and applied to adsorb the emerging contaminants ibuprofen and ketoprofen from diluted solutions. The study of the adsorption process was focused on the evaluation of pH effect, kinetic behavior, equilibrium curves and thermodynamic parameters estimation. Moreover, a simulated pharmaceutical effluent was treated with the magnetic adsorbent produced. The characterization results demonstrated that NiAC presented functional groups of activated carbon coupled with intrinsic characteristics of the metal tetrahedral site. NiAC was composed by crystalline NiFe2O4 and amorphous carbon structures, presented high values of surface area (564.4 m(2) g(-1)) and a sufficient magnetic character to be separated from the liquid phase by an external magnetic field. SEM images showed cavities and protuberances typical of activated carbon and an agglomeration of small magnetic particles due to NiFe2O4 presence. The adsorption was favored in acid conditions and at 328 K. Kinetic behavior was well modeled by the pseudo second order equation, while the equilibrium curves followed the Sips model, with maximum adsorption capacity of 261.35 mg g(-1) and 97.75 mg g(-1) for ibuprofen and ketoprofen, respectively. Spontaneous and endothermic processes controlled by physisorption occurred. The NiAC material was efficient to treat a simulated pharmaceutical effluent, with removal percentage of 86.46%. NiFe2O4/activated carbon magnetic composite has a great potential to be used as adsorbent to remove emerging pharmaceutical contaminants from diluted solutions. (C) 2019 Elsevier Ltd. All rights reserved.