Boosting the catalytic activity of nanostructured ZnFe2O4 spinels incorporating with Cu2+ for photo-Fenton degradation under visible light

Abstract

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, Cu²⁺-substituted ZnFe₂O₄ nanomaterials (Cu_xZn_1-xFe₂O₄; 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 (H₂O₂). The feature of the photo-catalysts was determined by XRD, EDX, FTIR, DRS, BET, SEM, and TEM techniques. Incorporation of Cu²⁺ 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 Cu²⁺ ions, H₂O₂ concentration, adsorbent dosage, and MB concentration. As a result, the photocatalytic MB degradation efficiency by Cu_0.6Zn_0.4Fe₂O₄ catalyst was 99.83% within 90 min under LED light (λ ≥ 420 nm), which was around 4 folds higher than that of pure ZnFe₂O₄. The photo-Fenton kinetics were in accordance with the pseudo-first-order kinetic model (R² = 0.981), giving the highes rate constant of 0.034 min^-1. It can be, therefore, concluded that Cu²⁺ substitution considerably boosted the photocatalytic activity of Cu_xZn_1-xFe₂O₄ ZnFe₂O₄, suggesting a bright prospect of Cu_0.6Zn_0.4Fe₂O₄ as a photo-catalyst in the dyes wastewater treatment.

Keywords: Dye pollution; Metal doping; Methylene blue; Photocatalytic degradation; Water treatment; ZnFe2O4.