Magnetic ZnFe2O4/TiO2 nanoparticles-decorated HKUST-1 Heterostructure: Synthesis and visible light-activated Photocatalyst for degradation of cationic and anionic dyes

A visible light-responsive heterostructured magnetic metal-organic framework (MOF), ZnFe₂O₄/TiO₂/HKUST-1, its preparation, and performance in the degradation of methylene blue (MB) and methyl orange (MO) dyes were compared with the performance of ZnFe₂O₄/TiO₂ and ZnFe₂O₄ nanoparticles. Removal experiments were conducted under various conditions, including pH, photocatalyst mass (g), temperature (°C), and dye concentration (mg/L), and the effect of each of these factors on photocatalyst performance was evaluated. Under optimal conditions, the ZnFe₂O₄/TiO₂/HKUST-1 photocatalyst exhibited degradation efficiencies of 97.88 % and 98.93 % for MB and MO dyes, respectively. The results indicate that after 5 cycles, the photocatalyst recovery efficiency is 93.68 % and 95.01 % for MB and MO dyes, respectively. Based on the findings derived from the experiments concerning the degradation of MB and MO dyes, the peak correlation coefficients recorded was 0.9956 and 0.9799, respectively, which pertain to the intraparticle diffusion (IPD) kinetics. Furthermore, evaluation of thermodynamic parameters showed that the Gibbs free energy changes (ΔG°) were negative at all temperatures investigated in the MB and MO photocatalytic processes, indicating that these processes occur spontaneously. In addition, the negative enthalpy changes (ΔH°) during the removal process using ZnFe₂O₄/TiO₂/HKUST-1 indicate the exothermic nature of this process.