Visible light-driven cubic structured NiFe2O4@MWCNTs/TiO2 ternary nanocomposite for photocatalytic degradation of ciprofloxacin

Abstract

A nanocomposite (TiO₂/NiFe₂O₄@MWCNTs) was synthesized through hydrothermal methods, combining NiFe₂O₄, TiO₂, and MWCNTs. The material underwent characterization using various analytical methods, including XRD analysis, SEM, TEM, EDS, UV-vis spectroscopy, PL analysis, FT-IR, Raman spectroscopy, and BET analysis. The average size of a nanoparticle is 36 nm, as determined by transmission electron microscopy and the Scherrer formula. UV-visible examination reveals that the TiO₂/NiFe₂O₄@MWCNTs nanocomposite has an energy band gap of 1.5 eV. The resultant nanocomposite has a specific surface area of 70.5 m² g⁻¹ and a pore volume of 0.29 cc g⁻¹. These analyses demonstrated that the inclusion of MWCNTs effectively inhibited charge carrier recombination in both NiFe₂O₄ and TiO₂ nanoparticles. The catalyst's efficiency was evaluated in a batch reactor under diverse conditions, including different nanocomposite dosages, CIP concentrations, and pH levels. The degradation of CIP was explored through photocatalytic experiments with varying nanocomposite dosages, revealing that a dosage of 0.5 g L⁻¹ resulted in an 83.5% degradation efficiency (CIP: 40 mg L⁻¹, pH = 6, 120 min, 120 W m⁻²). Different CIP concentrations were also tested, showing that a concentration of 10 mg L⁻¹ achieved a degradation performance of 93.5% (catalyst: 0.5 g L⁻¹, pH = 6, 120 min, 120 W m⁻²) and an efficiency of 97.2% at a pH of 10. The optimal conditions for CIP degradation were determined as 0.5 g L⁻¹ of nanocatalyst, a CIP concentration of 10 mg L⁻¹, and a pH of 10. These optimal parameters were then applied to assess CIP degradation using NiFe₂O₄ and NiFe₂O₄/MWCNTs as individual materials. Trapping analyses have established that H⁺ and OH˙, which are reactive radicals, are the main agents responsible for the breakdown of CIP. The highest agreement with the experimental data was obtained by applying a pseudo-first-order kinetic model, which had an R² value of 0.97 for a range of CIP concentrations. Notably, even after four consecutive uses, the photocatalysts maintained their original efficiency, experiencing a minimal decrease of less than 3.2% in CIP degradation. Due to its straightforward synthesis, excellent stability, and potential for recycling, TiO₂/NiFe₂O₄@MWCNTs demonstrated promising performance in degrading CIP antibiotics, suggesting its suitability for removing and breaking down pharmaceutical organic contaminants in water systems.