To identify the impact of biomolecules from the grape leaf extract on the reactivity of Fe NPs, the comparative assays on the removal efficiency of Orange II using Fe NPs and grape leaf extract as control experiment were investigated under the same conditions. Meanwhile, to overcome the influence of precursor, assay was also conducted using ferrous chloride. The same reacted quantity of the grape leaf extract (2 mL), ferrous chloride solution (2 mL, 0.01 mol/L) and the formed Fe NPs solution (4 mL) were firstly dried separately using a pressure blowing concentrator, and then reacted with 10 mg/L of Orange II (2 mL) under the conditions (T = 295 K, pH ≈ 6.0). Several parameters including a solution of PI-103 Hydrochloride (3.0, 6.0, 9.0), dosage of Fe NPs (1.0, 2.0, 6.0, 10.0 mg), initial concentration of Orange II (5, 10, 20 mg/L) and reaction temperature (295, 305, 315 K) were investigated. The conditions were initially set at 2 mL of 10 mg/L Orange II, 10.0 mg of Fe NPs, 295 K and pH 6.0. Diluted hydrochloric acid and diluted sodium hydroxide were used to adjust pH in this experiment. The degraded solutions were firstly filtered through 0.80 μm membranes, and then measured using a UV-spectrophotometer (Lambda 18, PerkinElmer) at 485 nm. The amount of dye adsorbed per unit weight of Fe NPs at t time and removal efficiency of dye using Fe NPs was calculated using the following equations:equation(1)qt=(C0−Ct)Vmequation(2)R(%)=C0−CtC0×100where V is the volume of solution (L), m is the mass of Fe NPs (g), R (%) is the degradation efficiency of dye, C0 (mg/L) is the initial concentration of dye in the solution, and Ct (mg/L) is the concentration of acid dye at t min.