Fig. 4. Parameters affecting the degradation of ONZ. (a) nZVI dosage (C₀ = 100 mg L⁻¹, pH = 5.80, T = 25 °C); (b) initial ONZ concentration (nZVI dosage = 0.1 g L⁻¹, pH = 5.80, T = 25 °C); (c) pH value (nZVI dosage = 0.1 g L⁻¹, C₀ = 100 mg L⁻¹, T = 25 °C); (d) temperature (nZVI dosage = 0.1 g L⁻¹, C₀ = 100 mg L⁻¹, pH = 5.80); (e) air and oxygen (nZVI dosage = 0.1 g L⁻¹, C₀ = 100 mg L⁻¹, pH = 5.80, T = 25 °C).