An effective magnetic nanoadsorbent based on a carbonaceous/spinel ferrite nanocomposite for the removal of pharmaceutical pollutants from wastewater

Abstract

Activated carbon modified with metal ferrite CoFe₂O₄ nanoparticles (AC–CoFe₂O₄) was prepared as a magnetic nanoadsorbent for removing promazine (PZ) from wastewater. The prepared AC–CoFe₂O₄ nanocomposite was characterized by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and N₂ sorption measurements. The impacts of operational parameters such as nanoadsorbent dosage, adsorbate concentration, and initial solution pH on PZ adsorption efficiency were investigated. The PZ adsorption on the magnetic nanoadsorbent followed pseudo-second order kinetics and the Langmuir isotherm model with a maximum adsorption capacity of 90.91 mg g⁻¹. Furthermore, the effect of competing ions present in tap water on the adsorption capacity of AC–CoFe₂O₄ was studied by performing adsorption experiments in tap water in lieu of DI water. Interestingly, the maximum adsorption slightly decreases to 76.92 mg g⁻¹. Mixed pharmaceutical pollutant adsorption was performed by mixing PZ and diclofenac (DIC) and both were adsorbed from water with adsorption efficiencies of 94.08 and 84.40%, respectively. Additionally, the reusability study revealed that the AC–CoFe₂O₄ magnetic nanoadsorbent can be lucratively recycled without a significant loss of adsorption efficiency and SEM revealed the high stability of the nanoadsorbent after performing five adsorption–desorption cycles. Fourier transform infrared spectroscopy (FTIR) and XPS were utilized to elucidate the adsorption mechanism and revealed the presence of electrostatic and π–π interactions. The presented nanoadsorbent was proven to be efficient for removing acidic and basic pharmaceuticals from wastewater, showed high stability, and can be recycled and regenerated using a magnetic field.