BACKGROUND: The increasing contamination of water bodies with industrial dyes necessitates efficient remediation strategies.
CuO–ZnO composite nanoparticles (NPs) have shown promise as adsorbents due to their high surface area, stability, and tunable
properties. This study focuses on optimizing the synthesis conditions of CuO-ZnO NPs via a co-precipitation method and
evaluating their performance for the removal of Reactive Black 5 (RB5) dye.
RESULTS: CuO–ZnO composite NPs were synthesized with varied precursor ratios, pH values, temperatures, and reagent addition
times to achieve optimal size and stability. Characterization using ultraviolet–visible spectroscopy, fluorescence, X-ray diffraction,
Fourier transform infrared spectroscopy, dynamic light scattering, vibrating-sample magnetometry, and Brunauer–
Emmett–Teller analysis confirmed the structural, optical, and physical properties of the optimized composite. The smallest size
and highest stability for a concentration ratio of 50:50 was obtained at pH 11, 80 °C, and a reagent addition time of 5 min. Composite
NPs show ferromagnetic behavior. The adsorption efficiency of RB5 dye was studied under different operational parameters,
revealing that maximum removal (92%) occurred at pH 2 with a contact time of 60 min. Adsorption kinetics followed the
pseudo-first-order model, while equilibrium data aligned with the Freundlich isotherm, indicating multilayer adsorption. Thermodynamic
analysis confirmed the endothermic and spontaneous nature of the process.
CONCLUSION: The optimized CuO–ZnO composite NPs demonstrated high efficiency for RB5 dye removal and maintained significant
reusability across multiple adsorption–desorption cycles. These findings highlight the potential of CuO–ZnO NPs as an
effective and sustainable adsorbent for wastewater treatment.
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