Synthesis of magnetically separable and recyclable MnFe₂O₄@SiO₂@NH₂ nanocomposite coupled-acylated MWCNT_S with enhanced photocatalytic performance under visible-light irradiation

A MnFe₂O₄@SiO₂@NH₂ coupled with acylated multi-walled carbon nanotubes (AMWCNT_S) was prepared using an easy one-step modification approach and applied for the visible light-assisted removal of ciprofloxacin (CIP). FT-IR, XRD, VSM, Raman spectrum, FE-SEM, BJH/BET, UV-Vis, and band gap analysis were used to characterize nanocomposites. In terms of CIP removal, the nanocomposites outperformed both AMWCNT_S and MnFe₂O₄@SiO₂@NH₂ nanoparticles. At a pH of 7, an initial CIP concentration of 25 mg·L⁻¹, a reaction time of 40 min, and a catalyst dose of 0.8 g·L⁻¹, all of the CIP was degraded. The ratios of BOD₅/COD (5-day biological oxygen demand/chemical oxygen demand) and BOD₅/TOC (5-day biological oxygen demand/total organic carbon) at the beginning of the process were 0.22 and 0.71, respectively, and reached 0.755 and 1.21 at the end of the process, which signposts the conversion of non-biodegradable wastewater into biodegradable wastewater. Scavenger studies disclosed that hydroxyl radicals and holes had the greatest effect on the degradation of CIP. The toxicity of the final effluent was also investigated with E. coli bacteria, and the results showed a very good effect of the process in the field of effluent sterilization. Equilibrium data fully followed first-order kinetics, with a reaction rate constant of 0.109 min⁻¹. Also, the half-life for the complete degradation of CIP was equal to 6.8 min. The CIP removal efficiency still remained at 9.4% in the five cycles. MnFe₂O₄@SiO₂@NH₂@AMWCNT_S gave a pronounced potential for eliminating CIP from aqueous environment.