*2.1. Materials*

Anhydrous ethanol (CH3CH2OH, 99.7%) was obtained from Fuyu Chemical Co., Ltd. (Tianjin, China). Sodium borohydride (NaBH4, 97.0%), potassium nitrate (KNO3, 99.0%), potassium persulfate (K2S2O8, 99.0%), ammonium chloride (NH4Cl, 99.8%), and sodium nitrite (NaNO2, 99.0%) were acquired from Kermel Chemical Reagent (Tianjin, China). Ferrous sulfate heptahydrate (FeSO4·7 H2O, 99.0%) was purchased from Sheng Ao Chemical Reagent (Tianjin, China). The raw pine sawdust was collected from Weinan, Shaanxi Province, China. The sawdust was rinsed three times with deionized (DI) water and then dried overnight in an oven at 80 ◦C. nZVI used for comparison were purchased from Xiangtian Nanomaterials Co., LTD., Shanghai, China.
