Boosting the catalytic activity of nanostructured ZnFe 2 O 4 spinels incorporating with Cu 2+ for photo-Fenton degradation under visible light.

Methylene blue (MB) is hazardous in natural water because this dye causes serious diseases that endangers public health and ecosystems. Photocatalytic degradation is a prominent technique for achieving the effective elimination of dye pollutants from wastewater and contribute vitally to ecology and environmental safety. Herein, Cu ²⁺ -substituted ZnFe ₂ O ₄ nanomaterials (Cu _x Zn _1-x Fe ₂ O ₄ ; x = 0, 0.1, 0.2, 0.3, 0.4, 0.6) were synthesized, characterized, and applied for the photocatalytic degradation of MB dye beneath visible light with the assistance of hydrogen peroxide (H ₂ O ₂ ). The feature of the photo-catalysts was determined by XRD, EDX, FTIR, DRS, BET, SEM, and TEM techniques. Incorporation of Cu ²⁺ ions changed the crystalline phase, particle size, morphology, and surface area. The photocatalysis condition was optimized with the following major factors, the amout of doping Cu ²⁺ ions, H ₂ O ₂ concentration, adsorbent dosage, and MB concentration. As a result, the photocatalytic MB degradation efficiency by Cu _0.6 Zn _0.4 Fe ₂ O ₄ catalyst was 99.83% within 90 min under LED light (λ ≥ 420 nm), which was around 4 folds higher than that of pure ZnFe ₂ O ₄ . The photo-Fenton kinetics were in accordance with the pseudo-first-order kinetic model (R ²  = 0.981), giving the highes rate constant of 0.034 min ^-1 . It can be, therefore, concluded that Cu ²⁺ substitution considerably boosted the photocatalytic activity of Cu _x Zn _1-x Fe ₂ O ₄ ZnFe ₂ O ₄ , suggesting a bright prospect of Cu _0.6 Zn _0.4 Fe ₂ O ₄ as a photo-catalyst in the dyes wastewater treatment.
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